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Guide to OpenVMS File Applications

1. DEC DEC DEC VMS VMS VMS e Current DSIs Byte Ds Structure Position 0 C E D 85 0 0 0 0 89 0 0 0 0 93 DSIS VENDOR INDENTIFIER 0 Ss M Y 97 0 0 0 0 101 0 0 0 0 105 DSISSOFTWARE IDENTIFIER 0 0 109 DSISFILE SYSTEM IDENTIFIER 0 0 0 x 113 DSISFILE SYSTEM VERSION X 0 1 or 2 See e 9 Binary Hex Encoded File Attribute Block 0 6 0 2 0 2 47 FAT W_RSIZE FAT B_RATTRIB FAT B_RTYPE 0 0 0 3 0 0 0 0 121 FAT L_HIBLK 0 0 0 2 0 0 0 0 FAT L EFBLK 125 0 0 0 0 0 0 4 Cc 129 FAT B VFCSIZE FAT B BKTSIZE FAT W_FFBYTE 0 0 0 0 0 0 0 0 133 FAT W DEFEXT FAT W_MAXREC 0 0 0 0 FAT W GBC ud Not Used and Not Encoded 141 0 0 0 0 145 FATS W VERSIONS FAT V RTYPE Bits 0 3 FAT V FILEORG Bits 4 7 The high and low order 16 bits are transposed for compatibility with PDP 11 software FAT B_RTYPE Record Type VAR Org Sequential FAT B_RATTRIB Implied Carriage Control 4 No 02 02 6400 0 Hex Encoded Byte Stream N bed N A br NOt N C N 0000300 00000200 4C00 00 00 0000 0000 0000 0000 FAT W_RSIZE 100 FAT L_HIBLK 03 FAT L_EFBLK 02 FAT L_FFBYTE 76 FAT B_BKTSIZE 0 FAT B_VFCSIZE 0 FAT W_MAXREC 0 FAT W_DEFEXT 0 FAT W_GBC 0 r FAT W_VERSIONS 0 ZK 5075A GE Introduction 1 17 Introduction 1 3 Magnetic Tape Concepts 1 3 Magnetic Tape Concepts This section describes magnetic tape concepts Data records are organi
2. DIRECT E OPENING error opening DIR as input RMS E DIR error in directory name You can refer to a specific subdirectory of the root directory in the same way that you refer to a top level directory using normal directory syntax as shown in the following example DEFINE BASE DUA7 ROOT1 SET DEFAULT BASE SUBDIR You can refer to any subdirectory beneath the root directory using wildcard characters to vertically traverse the directory tree You can refer to all directories below the root directory all directories one level below the root directory all directories two levels below the root directory and other reference combinations as shown in the following example DEFINE TRANSLATION ATTR CONCEALED BASE DUA7 ROOT1 DIR BASE DIR The system responds with the following display BASE SUBDIR SUBSUBDIR DIR BASE SUBDIR SUBSUBDIR SUBSUBSUBDIR DIR BASE OTHERSUB 6 16 Advanced Use of File Specifications Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concatenation OTHERSUBSUB DIR With rooted directory syntax RMS uses the process default device and directory indirectly as defaults This occurs because RMS uses the expanded rooted device logical name device and root directory before applying the process default device and directory With rooted directory syntax you can use relative directory syntax such as the hyphen and leading period
3. In random access by key mode RMS provides two forward search key options for use with one of four match options see Section 8 4 3 2 A reverse search key option permits reverse random access when used in combination with either of the two forward search key options The search key options are e The equal or next key option FDL attribute CONNECT KEY GREATER EQUAL searches the file forward toward the end of the file to return the next record whose key value is equal to or greater than the current key of reference according to sort order e The next key option FDL attribute CONNECT KEY GREATER THAN searches the file forward toward the end of the file to return the record whose key value is greater than the current key of reference according to sort order The reverse search key option is used with either the equal or next key option or the next key option to access selected records in reverse order This option does not reverse the direction of sequential access operations which are always done in the forward direction according to sort order If the reverse search key option is used with the equal or next key option RMS searches the file backward toward the beginning of the file to return the previous record whose key value is equal to or less than the current key of reference assuming according to sort order If the reverse search key option is used with the next key option RMS searches the file backward toward t
4. The following Compaq CRTL functions accept OpenVMS extended file names and require this syntax for a leading tilde in the file specification create fopen freopen open Stat 5 2 9 2 DCL Parsing Anomaly Prior to OpenVMS Version 7 2 DCL parses some file specifications incompletely and does not detect all illegal ODS 2 file specifications Specifically if a file specification has three comoponents separated by two delimiters DCL does not verify that the second delimiter is a semicolon and the third component is a version number However RMS verifies the file specification completely and detects errors that DCL may miss For example on an ODS 2 volume SCREATE A B C CREATE E OPENOUT error opening A B C as output RMS F SYN file specification syntax error For compatibility this behavior has been preserved However this can produce unexpected results when accessing an ODS 5 volume under the following conditions e The parsing style is traditional the default e The file specification is illegal on ODS 2 e DCL does not detect the error The file specification is legal on ODS 5 Under these conditions the command CREATE A B C succeeds on an ODS 5 volume However you cannot access the file with a DCL command that requires a version number such as the DELETE command For example SDELETE A B C DELETE E DELVER explicit version number or wild card required SDELETE A B C 1 DCL W PARMDEL invalid paramete
5. When the Edit FDL utility creates an FDL file it groups the attributes into major sections The section headings are called primary attributes and the attributes within a primary section are called secondary attributes Certain secondary attributes contain a third level of attributes called qualifiers The objective of using the Edit FDL utility is to create an FDL file with optimum values for the various attributes An FDL file contains a list of the primary and secondary attributes with related qualifiers If a primary or secondary attribute does not appear in the FDL file it is assigned its default value Example 4 2 shows an FDL file IDENT SYSTEM FILE RECORD AREA n and KEY n are primary attributes the others are secondary attributes Example 4 2 Sample FDL File IDENT 1 MAR 1993 14 07 46 OpenVMS FDL Editor SYSTEM SOURCE VMS FILE GLOBAL BUFFER COUNT 0 NAME DISKSRMS RMSTEST INDEXED DAT 3 ORGANIZATION indexed OWNER RMS1 TEST PROTECTION system RWED owner RWED group RE world RECORD BLOCK SPAN yes CARRIAGE CONTROL none FORMAT variable SIZE 2048 AREA 0 ALLOCATION 233 BEST TRY CONTIGUOUS yes BUCKET SIZE 5 EXTENSION 60 AREA 1 ALLOCATION 5 BEST TRY CONTIGUOUS yes BUCKET SIZE 5 EXTENSION 5 AREA 2 ALLOCATION 18 BEST TRY CONTIGUOUS yes BUCKET SIZE 3 EXTENSION 6 continued on next page Creating and Populating Files 4 9 Creating and Populating Files 4 1 File Creation Characteristics E
6. e Keep as much data in memory as possible but be wary of any significant increase in the page fault rate e Minimize the number of I O transfers by transferring larger portions of data e Arrange your data on the disk to minimize disk head motion 3 1 2 Space When you run your application you need space to buffer data in memory You can reduce data processing time by increasing the size of the I O buffers RMS uses however avoid exceeding the space limitations imposed by the working set In addition to the data buffers themselves the space required to store data can vary depending on the file organization you choose For example sequential file organization requires RMS to add an empty byte to a record when the record has an odd number of bytes but must be aligned on an even numbered byte boundary At the record level you should consider the added space required to prefix a two byte count field to each variable length record For the relative file organization RMS constructs a series of record storage cells based on the maximum length of the records The record cells are 1 byte longer than the size of fixed length records or 3 bytes longer than the maximum size specified for variable length records For the indexed sequential file organization RMS must add the following informational components to your data files e An index for each defined key e 15 bytes of formatting information for each bucket e A 7 byte header for ea
7. Number of Levels in Index 2 2 1 Number of Buckets in Index 72 72 1 Pages Required to Cache Index 216 216 27 Processing Used to Search Index 168 168 766 Key 0 Bucket Size 1 63 3 3 Key 0 Name 1 32 chars null SSNUM continued on next page 4 6 Creating and Populating Files Creating and Populating Files 4 1 File Creation Characteristics Example 4 1 Cont Sample Edit FDL Utility Session Global Buffers desired Yes No No NO The Depth of Key 0 is Estimated to be No Greater than 2 Index levels which is 3 Total levels Press RETURN to continue Z for Main Menu OpenVMS FDL Editor Add to insert one or more lines into the FDL definition Delete to delete one or more lines from the FDL definition Exit to leave the FDL Editor after creating the FDL file Help to obtain information about the FDL Editor Invoke to initiate a script of related questions Modify to change existing line s in the FDL definition Quit to abort the FDL Editor with no FDL file creation Set to specify FDL Editor characteristics View to display the current FDL Definition Main Editor Function Keyword Help EXIT DISK FOX RMS FDL SESSION EXAMPLE FDL 1 40 lines Q The Main Editor Function menu displays the Edit FDL utility commands eo The INVOKE command displays the Script Title Selection menu Note that HELP is the default command so if you want online help just press the Return key The Script Title
8. Section 10 1 describes how you can use the Analyze RMS File utility to view the characteristics of a file Section 10 2 describes how you can create an FDL file from a data file using the Analyze RMS File utility Section 10 3 explains how to use the Edit FDL utility particularly with Analyze RMS File to optimize and redesign file characteristics Section 10 4 describes how to make a file contiguous Section 10 5 explains how to reorganize a file and Section 10 6 describes how to make archive copies of a file 10 1 Viewing File Characteristics The Analyze RMS File utility ANALYZE RMS FILE allows you to inspect and analyze the internal structure of an OpenVMS RMS hereafter referred to as RMS file ANALYZE RMS FILE can check a file s structure for errors and can generate a statistical or summary report summary report is identical to a statistical report except that no checking is done For more information on producing a summary report see the description of the Analyze RMS File utility in the OpenVMS Record Management Utilities Reference Manual You can also inspect and analyze your file using the Analyze RMS File utility interactively The analysis can show whether or not the file is properly designed for its application and can point out ways to improve the file design In addition you can use ANALYZE RMS FILE to obtain FDL files from data files You can then use these FDL files with the Create FDL utility CREATE FDL the C
9. ccc eA 5 2 4 2 Compound Characters cles 5 2 4 3 Uppercase and Lowercase Letters and Multiple File Versions 5 2 4 4 Convert System Service llle eee eee 5 2 5 The Root Component 0 llle 5 2 6 The Directory Component cece eee 5 2 7 The File Name Type and Version Components 5 2 8 Leading Hyphens in File and Subdirectory Names Alpha Only 5 2 9 Restrictions and Anomalies llle 5 2 9 1 Restriction with Extended File Names llle 5 2 9 2 DCL Parsing Anomaly 0 0 cece eh 5 3 Logical Names and Parsing 0 0 0 0 eee eet ee eee 5 4 File Specification and Component Length Limits 5 4 1 VAX Systems and ODS 2 Disks on Alpha Systems 5 4 2 ODS 5 on Alpha Systems 1 ees 5 4 3 Maximum Subdirectory Depths llle 5 4 4 Accessing Files on ODS 5 Disks from VAX Systems 5 4 5 Determining the Structure Level of a Disk Device 5 4 6 Using File Specification Defaults 0 0 0 0 eee ee eee 5 5 Image Activation Using Logical Names 0 0 0 0 cc eee eee 5 6 Sample Use of Logical Names 0 0 eee eee 5 7 Types of Logical Names 4 16 4 16 4 19 4 20 4 22 4 23 4 23 4 25 4 25 4 26 4 26 4 27 4 27 4 27 4 31 4 31 4 32 4 34 5 2 Haas Gate ero e TTT ICE Ge Geeks mds ool Ld dE d d ORCI o ooocdooooo0 oo Q1GO
10. the records are written to a carriage control device such as a line printer or terminal If form control is not specified when a file is created this is the default Buffer Offset Length Field For implementations that support buffer offsets the buffer offset length field indicates the length of information that prefixes each data block The magnetic tape file system supports the input of buffer offset which means that the buffer offset length obtained from the HDR2 label when reading the file is used to determine the actual start of the data block The magnetic tape file system does not support the writing of a buffer offset Note that if you open a file for append or update access and the buffer offset length is nonzero the open operation will not succeed Introduction 1 33 Introduction 1 3 Magnetic Tape Concepts 1 3 1 7 Trailer 1 4 Using 1 3 1 6 3 HDR3 Label The HDR3 label describes the RMS file attributes For RMS operations data in the HDR3 label supersedes data in the HDR2 label Although the HDR3 label usually exists for every file on an ANSI magnetic tape volume there are two situations when this label will not be written The first is when an empty dummy file is created during volume initialization no HDR3 label is written because the empty file does not require RMS attributes The second is when you specify MOUNT NOHDRS at mount time You should use the NOHDR3 qualifier when you create files on volumes that
11. 1 or 2 bytes 1 or 3 bytes 7 to 13 bytes Record Operations Connect Yes Yes Yes Delete No Yes Yes Disconnect Yes Yes Yes Find Yes Yes Yes lAlthough these file organizations are not compatible with magnetic tape operations you may use magnetic tape to transport the files 2Unit record devices include printers terminals card readers mailboxes and so forth 3Fixed length records and records with undefined format use no overhead stream records use either 1 or 2 bytes of overhead variable length and VFC records use 2 bytes of overhead 4Fixed length records use 1 byte of overhead variable length records and VFC records use 3 bytes of overhead extra overhead applies to each cell 5Prolog 1 and Prolog 2 fixed length records use 7 bytes of overhead Prolog 1 and Prolog 2 variable length records use 9 bytes of overhead For Prolog 3 fixed length records use 9 bytes of uncompressed overhead and variable length records use 11 bytes of uncompressed overhead For key compression add 2 bytes of overhead continued on next page 2 14 Choosing a File Organization Choosing a File Organization 2 2 File Organization Concepts Table 2 2 Cont File Organization Characteristics Characteristics Sequential Relative Indexed Record Operations Flush Yes Yes Yes Free Yes Yes Yes Get Yes Yes Yes Rewind Yes Yes Yes Truncate Yes No No Update disk only Yes Yes Yes Put Yes Yes Yes I O Unit 1 or more Bucket Bucket
12. A single file can be accessed by both interlocked interprocess file sharing and multistreaming Compaq does not recommend the simultaneous use of interlocked interprocess file sharing and user interlocked interprocess file sharing on the same file if the process that requests user interlocked interprocess file sharing intends to modify the file The reason is that record locking is not done or checked for the processes using user interlocked interprocess file sharing You must define your process access based on planned record operations The record operations with associated FDL and RMS options are summarized in Table 7 1 Table 7 1 File Access Record Operations Function Service FDL and RMS Options Read records Get ACCESS GET specified or FAB B FAC field FAB V_ GET set Locate records Find ACCESS GET specified or FAB B FAC field FAB V GET set Delete records Delete ACCESS DELETE specified or FABSB FAC field FAB V DEL set Add new records Put ACCESS PUT specified or FAB B FAC field FAB V_ PUT set Truncate file Truncate ACCESS TRUNCATE specified or FAB B FAC field FAB V TRN set Modify records Update ACCESS UPDATE specified or FAB B FAC field FAB V UPD set Access blocks see text ACCESS BLOCK IO specified or FAB B FAC field FAB V BIO set under certain conditions ACCESS RECORD IO or FAB B FAC FAB V_BRO The record access functions you request are compared with the protection on the specified file If your p
13. CONVSPASS OPTIONS USING BY CONTENT OPTIONS GIVING STATVALUE IF STATVALUE IS FAILURE CALL LIBSSTOP USING BY VALUE STATVALUE 4 30 Creating and Populating Files CUSTDATA DAT continued on next page Creating and Populating Files 4 5 Populating a File Example 4 9 Cont Using the CONVERT Routines in a COBOL Program CALL CONVSCONVERT USING BY REFERENCE STATSBLK GIVING STATVALUE IF STATVALUE IS FAILURE CALL LIBSSTOP USING BY VALUE STATVALUE DISPLAY STATS DISPLAY Number of files processed NUM FILES CONVERSION DISPLAY Number of records NUM RECS CONVERSION DISPLAY Number of exception records NUM EXCS CONVERSION DISPLAY Number of valid records NUM VALRECS CONVERSION For more information about calling the Convert routines see the OpenVMS Utility Routines Manual 4 6 Summary of File Creation Options This section summarizes the file creation options that are available using RMS File creation options may be available as qualifiers or keywords to the OPEN statement and include various aspects of file creation including file disposition file characteristics file allocation and file positioning Note that the run time options for opening files in conjunction with creating files are not included here but they are described in Chapter 9 4 6 1 File Creation Options The following table lists the creation time options that apply to specifying how an application uses a file Name of Opt
14. COPY input filespec output filespec CONTIGUOUS If you do not want to rename the file use the same name for input filespec and output filespec Maintaining Files 10 27 Maintaining Files 10 4 Making a File Contiguous By default if the input file is contiguous COPY likewise tries to create a contiguous output file By using the CONTIGUOUS qualifier you ensure that the output file is copied to consecutive physical disk blocks The CONTIGUOUS qualifier can only be used when you copy disk files it does not apply to tape files For more information see the COPY command in the OpenVMS DCL Dictionary 10 4 2 Using the Convert Utility The Convert utility can also make a file contiguous if contiguity is an original attribute of the file To use the Convert utility to make a file contiguous use the following command syntax CONVERT input filespec output filespec If you do not want to rename the file use the same name for input filespec and output filespec 10 4 3 Reclaiming Buckets in Prolog 3 Files If you delete a number of records from a Prolog 3 indexed file it is possible that you deleted all of the data entries in a particular bucket RMS generally cannot use such empty buckets to write new records With Prolog 3 indexed files you can reclaim such buckets by using the Convert Reclaim utility This utility allows you to reclaim the buckets without incurring the overhead of reorganizing the file with CONVERT As th
15. CREATE FDL 1 39 EDIT FDL 1 39 with Prolog 3 files 10 28 RMS global buffer management scalability 7 24 RMS interface 5 1 RMS representation 5 5 RMS subdirectories extending 6 18 RMS GBLBUFQUO system parameter 1 40 Root component 5 8 Rooted device logical names 6 14 Rooted directory specifications concatenated 6 15 to 6 17 syntax 6 14 to 6 18 Root level 3 20 Rotationallatency 1 12 RRV record reference vector 3 10 3 23 RSX systems use of ODS 1 file structure with 1 4 Run time options example 9 22 to 9 23 specifying 9 1 to 9 5 S Save sets 10 29 Scalability RMS global buffer management 7 24 SCRIPT qualifier 10 26 Scripts list of 4 4 Optimize 10 1 Touch up 10 25 Search key option example program 8 10 Search key options 8 8 to 8 11 Search key types 8 9 Search lists See also File specifications definition 5 20 example 5 27 5 28 multiple file locations 5 20 5 21 translations 6 7 6 8 Search service 5 21 to 5 25 Secondary completion status value field 5 25 Secondary index data record See SIDR Secondary indexes See Alternate indexes Secondary services effect on next record position 8 18 Sectors 1 12 Seek time 1 12 Segmented keys 2 20 Semantics tags See File tags Sequential access 1 2 8 6 to indexed files 2 5 8 12 to relative files 2 3 8 8 use with sequential files 2 3 8 7 with multibuffer count 3 27 Sequential cell search in relative
16. FD to finish the design session Enter the title of your FDL file specification Enter the file specification of your data file Select the CARRIAGE_RETURN carriage control This display shows the tuning emphasis you chose to design your file It also shows suggested bucket sizes for various index level depths and other tuning information Select the default bucket size for the primary key Enter the name of the primary key Choose whether you want global buffers This message shows the depth of the primary key index and gives the total number of levels Press the Return key to display the main menu This is the main menu Use the EXIT command to exit the editor and to create the FDL file This message shows the resulting FDL file specification and the number of lines it contains Note that the example uses most of the suggested defaults There are three ways to accept defaults Press the Return key without entering a value Use the RESPONSES AUTOMATIC qualifier when you invoke the Edit FDL utility Use the following sequence 1 Select the SET command from the main menu 2 Select RESPONSES from the SET menu 3 Accept the default AUTO when the Edit FDL utility prompts for Default responses in script Key compression and index compression are not acceptable options when you select a collated key data type 4 8 Creating and Populating Files Creating and Populating Files 4 1 File Creation Characteristics
17. L1 Ul INTEGER OF CHAR VAR FAB PTR PTR TO FAB VAR RAB PTR PTR TO RAB INTEGER EXTERN FUNCTION FDLSGENERATE SREF FLAGS FDL2 TYPE FAB PTR PTR TO FAB RAB PTR PTR TO RAB STDESCR FDL FILE DST PACKED ARRAY Ll Ul INTEGER OF CHAR INTEGER EXTERN BEGIN Status FDLSPARSE TESTING TEMP FAB TEMP RAB if not odd status then LIBSSIGNAL status flags byte 0 status FDLSGENERATE flags temp FAB temp RAB SYSSOUTPUT if not odd status then LIBSSIGNAL status END For more information about FDL routines see the OpenVMS Utility Routines Manual 4 2 Creating a File After you select the creation characteristics for your file you use the selected characteristics to create the file You can create the file using one of the following e Create service e Create FDL utility e Convert utility e FDL CREATE routine 4 2 1 Using the Create Service The Create service creates a new data file assigning it the attributes you specify in the FAB and any applicable XABs Note that where there is a conflict the XAB fields override the FAB fields When you use the Create service to create a file the file remains open until you explicitly close it If you set the create if CIF bit in the FOP file processing options field of the FAB you can open an existing file with the Create service If the file you try to create has the same name as an existing file the Create service opens the exist
18. The performance of programs that use the other files is slower but the system as a whole runs faster In tuning your file management system you implement these trade offs and design decisions by specifying file design attributes together with various file processing options and record processing options Performance Considerations 3 3 Performance Considerations 3 2 Tuning 3 2 1 File Design Attributes The following file design attributes control how the file is arranged on the disk and how much of the file is transferred to main memory when needed These file design attributes generally apply to all three types of file organization other file design attributes that specifically pertain to the various file organizations are described under the appropriate heading e Initial file allocation e Contiguity e File extend quantity e Units of O e The use of multiple areas for indexed files e Bucket fill factor for indexed files The following sections discuss how each file design attribute can maximize efficiency 3 2 1 1 Initial File Allocation When you create a file you should allocate enough space to store it in one contiguous section of the disk If the file is contiguous on the disk it requires only one retrieval pointer in the header this reduces disk head motion You should also consider allocating additional space in anticipation of file growth to reduce the number of required extensions You can allocate space
19. WORKING STORAGE SECTION 01 MORE DATA FLAGS PIC X 3 88 THERE IS DATA 88 THERE IS NO DATA 01 STATVALUE PIC S9 9 01 OPTIONS USAGE IS COMP 02 NUM OPTS PIC S9 9 02 CREATE PIC S9 9 02 NOSHARE PIC S9 9 02 FASTLOAD PIC S9 9 02 NOMERGE PIC S9 9 02 NOPPEND PIC S9 9 02 XSORT PIC S9 9 02 XWORKFILES PIC S9 9 02 KEYS PIC S9 9 02 NOPAD PIC S9 9 02 PADCHAR PIC S9 9 02 NOTRUNCATE PIC S9 9 02 NOEXIT PIC S9 9 02 NOFIXEDCTRL PIC S9 9 02 NOFILLBUCKETS PIC S9 9 02 NOREADCHECK PIC S9 9 02 NOWRITECHECK PIC S9 9 02 FDL PIC S9 9 02 NOEXCEPTION PIC S9 9 01 STATSBLK USAGE IS COMP 02 NUM STATS PIC S9 9 02 NUM FILES PIC S9 9 02 NUM RECS PIC S9 9 02 NUM EXCS PIC S9 9 02 NUM VALRECS PIC S9 9 PROCEDURE DIVISION MAIN VALUE VALUE VALUE COMP VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE VALUE PERFORM CONVERT FILE THRU DISPLAY STATS OPEN INPUT IN FILE READ IN FILE YES YES NO oo CO r3 Co CO CO CO C5 Co C5 C C h2 r9 C CO rm c mp rL e 9 9 2 c oooo rfF AT END MOVE NO TO MORE DATA FLAGS CLOSE IN FILE STOP RUN CONVERT FILE CALL CONVSPASS FILES USING BY DESCRIPTOR SEQ DAT B BY DESCRIPTOR BY DESCRIPTOR INDEXED FDL GIVING STATVALUE IF STATVALUE IS FAILURE CALL LIBSSTOP USING BY VALUE STATVALUE CALL
20. and one for each of the records With the deferred write option you need only two I O operations one for the initial file access and one to write the bucket A larger cache might be useful in situations in which the accesses are not strictly sequential but follow some local pattern 3 5 Tuning an Indexed File This section discusses the structure of indexed files and ways to optimize their performance 3 5 1 File Structure An indexed file consists of a file header a prolog and one or more index structures The primary index structure contains the data records If the file has alternate keys it has an alternate index structure for each alternate key The alternate index structures contain secondary index data records SIDRs that provide pointers to the data records in the primary index structure The index structures also contain the values of the keys by which RMS accesses the records in the indexed file 3 5 1 1 Prologs RMS places information concerning file attributes key descriptors and area descriptors in the prolog You can examine the prolog with the Analyze RMS File utility described in Chapter 10 There are three types of prologs Prolog 1 Prolog 2 and Prolog 3 Prolog 1 and Prolog 2 Files Any indexed file created with a version of the operating system lower than Version 3 0 is either a Prolog 1 file or a Prolog 2 file Prolog 1 files and Prolog 2 files operate identically 3 18 Performance Considerations
21. as entered This is the default behavior In contrast the user may request RMS to notice case by using SET PROCESS CASE LOOKUP SENSITIVE also see the SYS SET PROCESS PROPERTIESW system service If the SENSITIVE option is in effect and the user creates more than one file on an ODS 5 disk with the same name differing only in case each file is treated as a new file At the file level the NAML V CASE LOOKUP flag can be used to instruct RMS to ignore or notice case for a file on an ODS 5 disk see the NAM L INPUT FLAGS field in the NAML structure in the OpenVMS Record Management Services Reference Manual NAML C CASE BLIND is set to tell RMS to ignore case or NAML C CASE LOOKUP SENSITIVE to notice case when creating deleting or searching for a file on an ODS 5 disk If the NAML structure is not used or this flag is zero the current process setting for CASE LOOKUP is used The SET PROCESS PARSE STYLE qualifier is independent of the CASE_ LOOKUP qualifier If the creation deletion or search of files on an ODS 5 disk is being done using the DCL command interface and case is relevant PARSE STYLE EXTENDED must be used to inform the DCL interface to preserve the Locating and Naming Files on Disks 5 7 Locating and Naming Files on Disks 5 2 File Specification Components case specified in the DCL command The CASE LOOKUP qualifier instructs RMS whether to ignore or notice the case either preserved or not 5 2 4 4 Convert System Servi
22. but you can update existing records continued on next page 2 18 Choosing a File Organization Choosing a File Organization 2 2 File Organization Concepts Table 2 4 Cont Relative File Organization Advantages and Disadvantages Advantages Disadvantages RMS does not allow duplicate relative record numbers The space taken up by each record is as long as the maximum record size 2 2 3 Indexed File Organization The indexed file organization allows sequential and random access of records on disk devices only This type of file organization lets you store data records in an index structure ordered by the primary key and retrieve data using index structures ordered by primary or alternate keys The alternate index structures do not contain data records instead they contain pointers to the data records in the primary index For example an indexed file may be ordered in ascending sort order by the primary key employee number However you may want to set up additional alternate indexes for retrieving records from the file Typically you might set up an alternate index in descending sort order by each employee s social security number Note The physical location of records in an indexed file is transparent to your program because RMS controls record placement In addition to the indexes each indexed file includes a prolog structure that contains information about the file including file attribute
23. e You can specify a lower level in the directory tree with a period to indicate that the current directory position SMITH JONES is prefixed to the specified directory as shown in the following command SET DEFAULT DATA This directory specification is combined with the current directory position to form SMITH JONES DATA e You can specify higher levels in the directory tree by beginning the directory specification with a hyphen to indicate that the directory specification is the next level up from the current directory level If you are currently at directory level SMITH JONES the following command directs RMS to use the directory SMITH SET DEFAULT If you include more than one hyphen RMS ascends the directory tree by a corresponding number of levels For example if you use the following command from directory level RED WHITE BLUE RMS moves up the tree to level RED SET DEFAULT e You can use combinations of hyphens and periods to traverse a directory tree For example assume the following directory tree structure ONE OON TWO THREE FOUR FIVE SIX SEVEN Assume that your process is in directory ONE TWO FOUR SIX and you want to access a file in ONE THREE FIVE You can do this with the following DCL command SET DEFAULT THREE FIVE 6 12 Advanced Use of File Specifications Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concate
24. following chart Name of Option Function Block size Bucket size Date information File organization 4 32 Creating and Populating Files Defines the number of bytes to be used in each block unit of I O throughout the life of this file This file characteristic applies only to magnetic tape files e FDL FILE MT BLOCK SIZE e RMS FAB W BLS Defines the number of blocks to be used in each bucket unit of I O throughout the life of this file This file characteristic applies only to relative and indexed files e FDL FILE BUCKET SIZE e RMS FAB B_BKS or XAB B BKZ Specifies the date and time values for file backup file creation file expiration and file revision Can also set the number of file revisions e FDL DATE attributes and FILE REVISION e RMS Date and Time XAB fields Defines the file organization sequential relative or indexed e FDL FILE ORGANIZATION e RMS FAB B ORG Creating and Populating Files 4 6 Summary of File Creation Options Name of Option Function File protection Fixed length control field size Key characteristics Maximum record number Maximum record size Defines the file protection for the file being created e FDL FILE OWNER FILE PROTECTION FILE MT PROTECTION e RMS Protection XAB fields Defines the number of bytes in the fixed length control field of a VFC record e FDL FILE CONTROL_FIELD_SIZE e RMS FAB B_FSZ Defines the characte
25. name When a directory component is missing RMS attempts to obtain the missing components from the process default directory Consider the rooted device logical name X defined as shown in the following DCL command DEFINE X DJB3 SMITH Now assume you set the default directory to JONES SET DEFAULT JONES When the rooted device logical name X is used with a directory specification all directory references are relative to the root directory SMITH Most wildcard characters that apply to normal directory syntax also apply to rooted directory syntax The following table lists the file specifications involving the rooted device logical name X and the directory that is accessed with each specification File Specification Directories Accessed X SMITH JONES X 000000 Root directory SMITH Xi SMITH JONES X Root directory SMITH listed as X 000000 X Invalid error X name SMITH name X name SMITH JONES name X name All directories in all directory trees below SMITH name X All directories one level below SMITH XG All directories in all directory trees below SMITH X All directories in all directory trees below SMITH JONES Note that RMS uses the default directory with relative directory references when the specified directory name contains a leading period or a hyphen or if no directory name is specified 6 3 5 An Example of Using a Rooted Directo
26. name NAM or NAML block for a valid device identification field NAM T DVI or NAML T_DVI directory identification field NAM W DID or NAML W DID and file identification field NAM W FID or NAML W FID If these fields are present RMS uses them to locate the file all other components are ignored because they are not needed If the open by name block succeeds no expanded or resultant string is produced If these fields are not present in the name block or if an open by name block is not specified for example an Open service not preceded by a Parse service RMS performs the translation and application of defaults A file can also be created using the name block device and directory identification fields but RMS does not use the file identification If an open by name block is requested for remote DECnet for OpenVMS file access between two OpenVMS systems RMS does not check the device identification directory identification or file identification to determine whether the requested open by name block operation can be performed Instead RMS checks to see if a qualified resultant string is present If a qualified resultant string is not present RMS translates logical names and applies defaults as if an open by name block operation was not requested see Section 6 2 2 6 2 2 File Specification Formats and Translating Logical Names To form the file specification RMS examines and attempts to translate each program supplied file specif
27. ranging from one to the maximum number of cells Writing new cells that are located substantially beyond the allocated space of the relative file is permitted Performance Considerations 3 5 Performance Considerations 3 2 Tuning The size of a relative file auto extend is initially set to the minimum number of disk blocks that must be allocated to reference the new cell The extend size is then rounded to the next bucket boundary so that the entire bucket containing the new record can be accessed This value is then maximized against the file default extension quantity If no file default exists this value is maximized against the volume default extension quantity The process and system default extension quantities are not applicable to auto extending a relative file Indexed File Extend Size Indexed files are auto extended by adding space to a particular area of the indexed file The extend size is always rounded to a multiple of the bucket size for the area being extended e Ifthe area being auto extended had an area default extension quantity specified when the indexed file was created or converted using an FDL that quantity is used for the extend size e Ifno area default extension quantity exists the file default extension quantity is used for the extend size e Ifno area or file default extension quantities are specified RMS auto extends the area by one bucket The process system and volume default extension quantit
28. see Chapter 10 The bucket size is specified by the FDL attribute FILE BUCKET SIZE VMS RMS control block field FAB B_BKS or XAB B_BKZ When choosing this value you should consider whether or not the file is usually accessed randomly small bucket size sequentially large bucket size or both medium bucket size as described in Chapter 2 1 This manual has been archived but is available on the OpenVMS Documentation CD ROM A printed book can be ordered by calling 800 282 6672 For information about the resources needed for file applications refer to Section 1 8 7 20 File Sharing and Buffering File Sharing and Buffering 7 3 Local and Shared Buffering Techniques You can specify the number of local buffers CONNECT MULTIBUFFER COUNT at run time The type of record access to be performed determines the best use of local buffers The two extremes of record access are that records are processed completely randomly or completely sequentially Also there are cases in which records are accessed randomly but may be reaccessed random with temporal locality and cases in which records are accessed randomly but adjacent records are likely to be accessed random with spatial locality For completely random or sequential access a single buffer should be specified In a processing environment in which the program processes records randomly and sometimes reaccessed records use multiple buffers to keep the reaccessed records in the buf
29. than one record However only the first record having the key value can be accessed randomly other records having the same key value can be accessed only sequentially Changeable keys This characteristic applies to alternate keys only When you specify changeable alternate keys the alternate keys in a record can be changed when the record is updated When an alternate key value changes RMS automatically adjusts the appropriate index to reflect the new key value Null keys This characteristic applies to alternate keys only When you fill an alternate key field with null characters RMS does not insert the record in the related index Note RMS excludes from the related index any record not long enough to contain a complete alternate key Key characteristics can be defined separately for each key 2 20 Choosing a File Organization Choosing a File Organization 2 2 File Organization Concepts When you do not allow duplicate key values RMS rejects any attempt to put a record into a file if it contains a key value that duplicates a key value already present in another record Similarly when alternate key values cannot be changed RMS does not allow your program to update a record by changing the alternate key value If you disallow a null value for a key RMS inserts an entry for the record in the associated alternate index Figure 2 12 illustrates the general structure of an indexed file containing only a primary key the e
30. which directly affects CPU time A larger fill factor decreases the room for growth in the file so bucket splits may occur Compression increases the record search time Alternatively you can reduce the index depth by decreasing the number of records in the file If you are using multiple areas you can set a different bucket size for each area You should use different bucket sizes if you are performing random accesses of records in no predictable pattern and if the data records are large Using different bucket sizes allows you to specify a smaller size for the index structures and SIDRs than for the primary data level You can use the Edit FDL utility to determine the optimum bucket size Use the same bucket size for all areas if the data records are small or if the record accesses follow a clustered pattern that is if the records that you access have keys that are close in value In general increasing the bucket size increases other resources e Levels in the tree structure e Buckets needed to maintain the tree structure e Buffers needed for cache Conversely decreasing the bucket size decreases the pages per bucket and the average number of keys searched while traversing the tree 3 5 2 2 Fill Factor If you know that the application makes random insertions into the database you should reserve some space in the buckets when records are first loaded into the file You can specify a fill factor from 50 to 100 For example a
31. 1 UNSAFE BOOLEAN FDL2 TYPE RECORD CASE INTEGER OF 1 FDL FDLDEF BITS BYTE 1 RECORD END 2 FDL V SIGNAL POS 0 BITI Signal errors don t return FDL V FDL STRING POS 1 BIT1 Main FDL spec is a char string FDLSV DEFAULT STRING POS 2 BIT1 Default FDL spec is a char string FDL V FULL OUTPUT POS 3 BIT1 Produce a complete FDL spec i j END mail order RECORD m order num KEY 0 INTEGER name PACKED ARRAY 1 20 OF CHAR address PACKED ARRAY 1 20 OF CHAR city PACKED ARRAY 1 19 OF CHAR State PACKED ARRAY 1 2 OF CHAR zip code KEY 1 PACKED ARRAY 1 5 OF CHAR item num KEY 2 INTEGER shipping REAL END order file UNSAFE FILE OF mail order ptr to FAB FABSTYPE T ptr to RAB RAB TYPE byte 0 255 VAR order master order file flags FDL2 TYPE order rec mail order temp FAB ptr to FAB temp RAB ptr to RAB status integer FUNCTION LIBSSIGNAL SREF cond val INTEGER IMMED num INTEGER immed 0 STDESCR sl PACKED ARRAY L1 U1 STDESCR s2 PACKED ARRAY L2 U2 EXTERN 4 14 Creating and Populating Files INTEGER OF CHAR INTEGER OF CHAR amp IMMED 0 amp IMMED 0 INTEGER continued on next page Creating and Populating Files 4 1 File Creation Characteristics Example 4 3 Cont Using FDL Routines in a Pascal Program FUNCTION FDLSPARSE SSTDESCR FDL FILE PACKED ARRAY
32. 1 2 3 Variable Length with Fixed Length Control Field VFC Record Format VFC records are similar to variable length records except that a fixed length control field is prefixed to the variable length data portion Unlike variable length records VFC records cannot be used in indexed files When you create a file for VFC records you must specify the value in bytes of the longest record permitted in the file If you accept the block span option the default the maximum VFC record size is 32767 bytes less the number of bytes in the fixed length control field If you specify no block spanning the maximum VFC record size is 510 bytes less the number of bytes in the fixed length control field For additional information about selecting the block span option see the OpenVMS Record Management Services Reference Manual Any attempt to store a record containing more bytes than the specified value results in an error If you specify a value of 0 any length record can be stored Choosing a File Organization 2 11 Choosing a File Organization 2 1 Record Concepts You must also specify the value in bytes of the fixed length control field The fixed length control field lets you include within the record additional data that may have no direct relationship to the other contents of the record For example the fixed length control field may contain line sequence numbers for every record in the file The program does not use the line sequence numbers
33. 1 82 2 11 Virtual block position option 4 36 VIRTUAL option 4 36 VOLI labels See Volume labels VOL labels See Volume labels VOLSET SYS file 1 10 VOLUME attribute 4 36 Volume default extension quantity 3 5 3 8 Volume identifier field 1 27 Volume labels EOF end of file label 1 22 EOV end of volume label 1 22 VOLI label 1 24 accessibility field 1 27 volume identifier field 1 27 VOL label 1 22 Volume number option 4 36 Volumes 1 7 ANSI magnetic tape 1 22 file configurations 1 23 1 24 label 1 22 mounting without HDR2 labels 1 33 multidisk 3 24 owner field 1 27 positioning 3 24 Volume sets 1 8 for improving performance 3 10 list file 1 10 loosely coupled 1 10 to minimize disk head competition 3 24 W Wait service 8 5 asynchronous operations and 8 19 WAIT FOR RECORD attribute 7 14 Wildcard characters See also File specifications multiple file locations 5 21 program preprocessing 5 21 to 5 26 Windows 9 7 to 9 9 sizes 10 27 Working sets 1 40 WRITE service use in calculating auto extend 3 5 X XAB B AID field 4 35 XAB B ALN field options 4 35 XAB B AOP field options 4 35 XAB B BKZ field 3 25 4 32 7 20 7 21 XAB L ALQ field 4 35 XAB L LOC field 4 35 4 36 XAB W DEQ field 4 36 XAB W VOL field 4 36 XABDAT blocks CDT field 1 31 EDT field 1 31 XABs extended attribute blocks 1 36 4 2 date and time fields
34. 14 9 18 RAB V WBH option 3 15 9 10 9 20 RAB L UBF field 9 17 RAB L USZ field 9 18 RAB W RBF field 8 2 RAB W RFA field 8 14 8 17 9 17 RAB W RSZ field 8 2 9 21 RABDEF macro 5 23 RABs record access blocks 1 36 Random access by key value 2 6 2 7 8 6 8 12 to 8 14 by relative record number 2 6 to 2 7 8 6 8 7 8 8 by RFA record file address 2 7 8 6 8 14 to indexed files 2 6 8 12 to 8 14 to relative files 2 6 8 8 8 14 to sequential files 2 6 8 7 8 14 with multibuffer count 3 27 RCW record control word 1 32 Read mode bucket locking 7 25 READ REGARDLESS attribute 7 14 Record access 9 6 9 10 See also Access in stream context 8 15 options 7 3 Record access blocks See RABs Record access modes 2 2 for indexed files 8 9 to 8 14 for relative files 8 7 8 9 for sequential files 8 7 sequential 2 2 8 6 8 8 8 12 specifying 8 6 8 7 9 10 9 17 9 19 Record buffering See Buffering techniques Record buffers 9 19 9 20 Record control word See RCW Record file addresses See RFAs Record formats 1 2 2 8 3 15 fixed length 1 2 1 31 2 9 2 10 3 15 3 22 selecting 2 1 stream 1 3 variable length 1 2 1 31 2 9 2 10 3 15 3 22 Record header buffer 9 17 9 19 9 20 Record length field 1 33 Record Management Services See RMS Index 11 Record operation 8 1 to 8 5 Record processing list of services 8 5 Record process
35. 2 3 Bad Block File The bad block file which is listed in the master file directory as BADBLK SYS 1 contains all the bad blocks on the volume The system detects bad disk blocks dynamically and prevents their reuse once the files to which they are allocated have been deleted 1 2 2 4 Master File Directory The master file directory MFD itself is listed in the MFD as 000000 DIR 1 The MFD which is the root of the volume s directory structure lists the reserved files that control the volume structure and may list both users files and users file directories Usually the MFD is used to list the reserved files and users file directories users seldom enter files in the MFD even on private volumes In fact on a private volume it is most convenient for a user to create a directory that has the same name as the user s default directory on a system disk Note Wildcard directory searches in the MFD always start after 000000 DIR to prevent recursive looping Therefore you should avoid creating any directories in the MFD that lexically precede 000000 When the Backup utility BACKUP creates sequential disk save sets it stores the save set file in the MFD For an explanation of user file directories and file specifications see the OpenVMS User s Manual 1 2 2 5 Core Image File The core image file is listed in the MFD as CORIMG SYS 1 It is not supported by the operating system 1 2 2 6 Volume Set List File The volume s
36. 20 extension size and 9 7 to 9 8 fast delete option and 9 8 global buffer count and 9 9 I O in OpenVMS Cluster 3 33 improving with null keys 3 22 in an OpenVMS Cluster 3 32 locate mode and 9 9 multiblock count 9 9 read ahead option 9 9 recommendations for an OpenVMS Cluster environment 3 33 sequential access 9 10 using Prolog 3 3 20 window size and 9 7 to 9 9 write behind option 9 10 Placement of extends 3 8 Pointer retrieval 9 7 POSITION attribute 4 36 Primary attributes 4 9 Primary record structures 10 18 Process default extension quantity 3 5 3 7 Processes types of resources 1 40 asynchronous system trap limit ASTLM 1 41 buffered I O limit BIOLM 1 41 TO limit DIOLM 1 41 Process I O segment 1 40 Processing deferred write option 3 18 3 28 options for improving file performance 3 10 read ahead option 3 14 3 15 write behind option 3 14 3 15 Process permanent files 1 40 access to 6 21 implications for indirect access 6 22 restriction to gathering RMS statistics 3 29 Process quotas resource limits 1 40 Programming interface 4 20 PROHIBIT attribute 7 4 Prolog 1 files 3 18 Prolog 2 files 3 18 Prolog 3 files 3 19 10 28 Prolog files 3 15 3 18 3 22 PROLOG structure 10 15 10 17 Protection access category 4 26 ACL based 1 35 4 26 disk and tape volumes 1 35 UIC based codes 1 35 4 26 PROTECTION attribute 4 33 PUT attribute 7 3 7
37. 4 Put service 8 1 8 3 to 8 4 effect on next record position 8 17 high level language equivalents 8 1 run time options 9 18 to 9 20 Q Query locking 7 10 Queue I O request system service 7 4 9 14 Queue I O services QIO call 1 20 R RAB B KRF field 9 13 9 15 RAB B KSZ field 8 7 8 8 8 14 9 18 9 16 9 18 RAB B MBC field 3 14 7 20 9 9 RAB B_MBF field 3 14 3 27 9 9 RAB B RAC field RAB C KEY option 8 6 9 10 9 17 9 19 RAB C RFA option 8 6 9 10 9 17 9 19 RAB C_SEQ option 8 6 9 10 9 17 9 19 RAB B TMO field 7 14 7 15 9 17 RAB L KBF field 8 7 8 8 8 14 9 13 9 15 9 18 RAB L RBF field 9 19 9 21 RAB L_RBZ field 9 19 RAB L RHB field 9 17 9 19 9 20 RAB L_ROP field 9 6 RAB V_ASY option 8 18 8 19 9 8 9 15 9 18 9 20 9 21 RAB V EOF option 8 15 8 17 9 10 RAB V EQNXT option 9 12 9 15 RAB V FDL option 9 8 9 12 9 21 RAB V KGE option 8 8 8 9 RAB V KGT option 8 8 8 9 RAB V LIM option 9 13 9 16 RAB V LOA option 9 13 9 18 RAB V LOC option 9 9 9 16 RAB V NLK option 7 RAB V NXR option 7 RAB V NXT option 9 3 T 7 7 RAB V RAH option 3 RAB V REA option RAB V RLK option RAB V RRL option 9 9 16 16 16 9 19 17 RAB L ROP field cont d RAB V_TMO option 7 14 7 15 9 17 9 19 RAB V TPT option 9 10 9 20 RAB V_UIF option 8 4 8 7 9 11 9 20 RAB V ULK option 7 16 9 16 RAB V WAT option 7
38. ANSI Labeled Magnetic Tape This section describes ANSI magnetic tape labels data and record formats supported by OpenVMS operating systems Note however that OpenVMS operating systems also support the ISO standard For a complete description of these labels please refer to the ANSI X3 27 1978 or ISO 1001 1979 magnetic tape standard Introduction 1 19 Introduction 1 3 Magnetic Tape Concepts 1 3 1 1 Logical Format of ANSI Magnetic Tape Volumes The format of ANSI magnetic tape volumes is based on Level 3 of the ANSI standard for magnetic tape labels and file structure for information interchange This standard specifies the format content and sequence of volume labels file labels and file structures According to this standard volumes are written and read on 9 track magnetic tape drives only The contents of labels must conform to prescribed data and record formats All labels must consist of ASCII a characters The ANSI magnetic tape format allows you to write binary data in the file sections see Figure 1 6 of files However if you plan to use such files for information interchange across systems make sure that the recipient system can read the binary data 1 3 1 2 RMS Magnetic Tape Ancillary Control Process MTAACP The RMS magnetic tape ancillary control process MTAACP is the internal operating system software process that interprets the logical format of ANSI magnetic tape volumes Transparent to your process
39. Alpha system It is possible to create directory trees on both ODS 5 and ODS 2 volumes that are deeper than RMS can display In those cases RMS will not display any subdirectories that lie beyond its limits 5 4 5 Determining the Structure Level of a Disk Device From DCL you can determine a disk device s structure level for example ODS 2 or ODS 5 via a SHOW DEVICE FULL command A DCL command procedure can determine the structure level with code such as the following DeviceName SYSSSYSDEVICE DeviceType FSGETDVI DeviceName ACPTYPE SIF DeviceType EQS F11V5 STHEN DeviceType ODS 5 SELSE IF DeviceType EQS F11V2 THEN DeviceType ODS 2 ELSE DeviceType is unknown SENDIF SENDIF SWRITE SYSSOUTPUT Disk DeviceName on disk structure is DeviceType SEXIT The structure level can be determined in a program executable image via a call to the SYS GETDVI system service using an item list with the DVI _ACPTYPE request code The following example in the C programming language displays a disk device s structure level of determining ODS 2 against ODS 5 5 14 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 4 File Specification and Component Length Limits ids Copyright 2001 Compaq Computer Corporation Compaq and the Compaq logo Registered in U S Patent and Trademark Office li li Confidential computer software Valid lic
40. Contiguous best try Cylinder boundary Cylinder position Allocates the file or area using the number of blocks specified by this value rounded up to the nearest even multiple of the volume s cluster size e FDL FILE ALLOCATION or AREA ALLOCATION e RMS FAB L_ALQ or XAB L_ALQ Allocates the file using single or multiple areas Applies only to indexed files sequential and relative files are always contained in a single area Indexed files can be placed in specific areas for example to separate the data area from the index area e FDL AREA number e RMS XAB B_AID Allocates the file or area using a single extent If the disk s unallocated space does not permit the file to be allocated contiguously an error is returned e FDL FILE CONTIGUOUS or AREA CONTIGUOUS e RMS FAB L_FOP FAB V_CTG or XAB L_AOP XAB V_CTG Attempts to allocate the file or area using a minimum number of extents If the file cannot be allocated contiguously an error is not returned e FDL FILE BEST_TRY_CONTIGUOUS or AREA BEST_TRY_CONTIGUOUS e RMS FAB L_FOP FAB V_CBT or XAB L_AOP XAB V_CBT Allocates the file or area at the beginning of a cylinder boundary e FDL AREA POSITION ANY_CYLINDER e RMS XAB B_AOP XAB V_ONC Positions the file or area at the beginning of the specified cylinder number e FDL AREA POSITION CYLINDER e RMS XAB B_ALN XAB V CYL and XAB L_LOC Creating and Populating Files 4 35 Creating and Populating
41. EXIT Creates the output FDL file stores the current FDL definition in it and terminates the Edit FDL utility utility session The Edit FDL utility leaves unchanged any FDL file that it used as input The FDL file that is created is by default a sequential file with variable length records and carriage return record attributes and has your process s default RMS protection and ownership HELP Displays the top level help text for the Edit FDL utility and then continues to prompt for more keywords Pressing the Return key in response to the Topic prompt or pressing Ctrl Z will return you to the main function prompt INVOKE Prompts you for your choice of scripts and starts a series of logically ordered questions that help you create new FDL files or modify existing ones MODIFY Allows you to change the value of one or more lines in the FDL definition Once you have changed a line you can continue to modify lines under that particular primary section QUIT Aborts the session without creating an output FDL file You can also press Ctrl C or Ctrl Y to abort the session SET Allows you to establish defaults or to select any of the Edit FDL utility characteristics you forgot to specify on the command line VIEW Displays the current FDL definition Causes the utility to display more information You can enter the question mark character in response to any question asked by the Edit FDL utility In all cases it will result in repetition o
42. FDL Utility Session D Maximum Record Size 0 80 32229 0 0 D Bin2 Bind Bin8 Int2 Int4 Int8 Decimal String Collated Dbin2 Dbin4 Dbin8 Dint2 Dint4 Dint8 Ddecimal Dstring Dcollated Key 0 Data Type Keyword Str STRING Key 0 Segmentation desired Yes No No NO Q key 0 Length 1 255 9 key 0 Position 0 32220 0 0 Key 0 Duplicates allowed Yes No No NO File Prolog Version 0 3 3 3 Data Key Compression desired Yes No Yes YES Data Record Compression desired Yes No Yes YES Index Compression desired Xes No Yes YES 9 8 Index 7 6 Depth 5 4 3 33 2 2222222222222222222222 1 11111111 T t t t t t t t t e 1 5 10 15 20 25 30 32 Bucket Size number of blocks PV Prolog Version 3 KT Key 0 Type String EM Emphasis Flatter 3 DK Dup Key 0 Values No KL Key 0 Length 9 KP Key 0 Position 0 RC Data Record Comp 0 KC Data Key Comp 0 IC Index Record Comp 0 BF Bucket Fill 100 RF Record Format Variable RS Mean Record Size 80 LM Load Method Fast Conv IL Initial Load 100000 AR Added Records 0 Type FD to Finish Design e Which File Parameter Mnemonic refresh FD Text for FDL Title Section 1 126 chars null FDL SESSION EXAMPLE Data File file spec 1 126 chars null EXAMPLE DAT Carriage Return Fortran None Print Carriage Control Keyword Carr CARRIAGE RETURN Emphasis Used In Defining Default Flatter files Suggested Bucket Sizes 3 3 27
43. FILE DAT 5 2 File Specification Components The following sections describe the particular file specification components 5 2 1 The Node Component Whether or not you should include the optional node component in a file specification depends on whether you confine file activity to the local node or you conduct file activity on remote nodes To locate a file on the local node or in an OpenVMS Cluster environment you do not have to include the node name in the file specification Note In this chapter discussions that refer to OpenVMS Cluster environments apply to both VAXcluster systems that include only VAX nodes and OpenVMS Cluster systems that include at least one Alpha node unless indicated otherwise Conversely to locate a file on a remote node you must present the name of the remote node either as the physical node name or as a logical name whose translation contains the physical node name A logical node name can also contain access control information used to log in to the remote system 5 2 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 2 File Specification Components 5 2 1 1 Local Node The following file specification format does not include a node name device root directory name filename type version This is the general format of a file specification used to locate a file on the local node or in an OpenVMS Cluster Note that a null node name of the form overrides any d
44. Figure 10 5 Key Descriptor Path Area Descriptors File Header File Attributes Key Descriptor Index Root Bucket Index Record Data Bucket Primary or Alternate Record ZK 0330 GE Maintaining Files 10 19 Maintaining Files 10 1 Viewing File Characteristics Figure 10 6 displays the structure of the primary records Figure 10 6 Structure of Primary Records Primary Record Bucket Referenced Actual Bytes of Data by RRV ZK 0332 GE As shown in Figure 10 6 the branch from the primary record structure allows you to either examine the actual bytes of data within the record or to follow the RRV Example 10 6 shows an examination of a primary record Example 10 6 Examining a Primary Record PRIMARY DATA RECORD VBN 4 offset X 000E Record Control Flags 2 IRC V DELETED 0 3 IRC V RRV 0 4 IRC V NOPTRSZ 0 Record ID 1 RRV ID 1 4 Byte Bucket Pointer 4 Key 765 4 3 2 1 0 01234567 31 30 30 30 30 30 0000 000001 ANALYZE gt DOWN BYTES 7 6 5 4 3 2 10 01234567 31 30 30 30 30 30 00 49 0000 1 000001 20 4C 41 54 49 47 49 44 0008 COMPAQ 4E 45 4D 50 49 55 51 45 0010 COMPUTER 52 4F 50 52 4F 43 20 54 0018 CORPORAT 31 31 20 4E 4F 49 54 41 0020 ION 110 42 20 54 49 50 53 20 30 0028 SPIT BRO 41 4F 52 20 4B 4F 4F 52 0030 OK ROAD 41 55 48 53 41 4E 20 44 0038 NASHUA 33 30 48 4E 20 20 20 20 0040 NH03 31 36 30 0048 062 ANALYZE UP continued o
45. Files 4 6 Summary of File Creation Options Name of Option Function Default extension Hard positioning Logical block position Related file position Virtual block position Truncate end of file Volume number Defines the minimum number of blocks for a file extension extent when additional disk space is needed For the Edit FDL utility file extension sizes see Appendix A e FDL FILE EXTENSION e RMS FAB W_DEQ or XAB W_DEQ Directs OpenVMS RMS to return an error if the requested file or area positioning or alignment cannot be performed e FDL AREA EXACT_POSITIONING e RMS XAB B_AOP XAB V_HRD Positions the file or area at the beginning of the specified logical block e FDL AREA POSITION LOGICAL e RMS XAB B ALN XAB V LBN and XAB L LOC Positions the file or area as close as possible to a related file at the specified virtual block e FDL AREA POSITION FILE ID or AREA POSITON FILE NAME e RMS XAB B ALN XAB V RFI and XAB L LOC Positions the file or area at the beginning of the specified virtual block e FDL AREA POSITION VIRTUAL e RMS XAB B_ALN XAB V_VBN and XAB L LOC Truncates a nonshared sequential file at its logical end to release the space between the logical end of the file end of file data and the physical end of the file allocated file space for other use e FDL FILE TRUNCATE ON CLOSE e RMS FAB V TEF Indicates the volume set where the file or area is placed when it is c
46. In addition the process executing the program supplies specific default values for device and directory components via the process default specification Where applicable RMS substitutes the translated logical name to the primary file specification before it applies default values After translating the primary file specification RMS applies the defaults from the default file specification then it applies the defaults from the related file specification if relevant RMS then applies the process default values where applicable for the device and directory to obtain the full file specification it uses to locate the file For more information about the application of defaults refer to Section 6 1 5 5 Image Activation Using Logical Names When an OpenVMS system activates an image it uses RMS to open the image file If the program specifies the image file with a logical name RMS uses the equivalence name to look up the image in the known file list unless the file specification includes a version number delimiter a semicolon or a period Known files are files that are installed using the Install utility and the known file list provides a listing of these files by name and by number file ID If RMS finds the file in the known file list it uses the file number to access the file directly on disk and bring it into memory for execution If the specified image file is not in the known file list RMS goes through the time consuming
47. NODLCKWT and RAB V NODLCKBLK in the new RAB W_ROP 2 field For more information about using these options see the flag information in the ENQ section of the OpenVMS System Services Reference Manual A GETUAI For more information about the lock manager see the OpenVMS System Services Reference Manual 7 3 Local and Shared Buffering Techniques One of the key performance factors is record buffering that is the transfer of records between a storage device and an area of memory accessible to the application program Between the storage device and the record buffer in the appliction program however is an intermediate buffer area that RMS maintains An intermediate buffer area is usually associated with each process you can also specify a shared buffer area for a shared file 7 3 1 Record Transfer Modes For synchronous and asynchronous record operations RMS provides two record transfer modes move mode and locate mode In move mode RMS copies a record from an I O buffer into a buffer that you specify For input operations data is first read into the I O buffer from a peripheral device such as a disk then moved to your application program buffer for processing For output operations you first build the record in your File Sharing and Buffering 7 17 File Sharing and Buffering 7 3 Local and Shared Buffering Techniques application program buffer then RMS moves the record to the I O buffer that is used to transfer the record to
48. PAY_ BUP DAT in any directory in the directory tree by using the following DEFINE command DEFINE SEARCH SMITH PAY SMITH PAY PAY SMITH PAY BUP You use the file specification SEARCH DAT to locate the desired file In this example note that one of the search list file specifications contains wildcard characters Wildcard characters can be used in a search list if they are needed just as with any other logical names and file specifications However the Parse and Search services must be used to locate the correct file When you need to locate files in different directory trees or top level directories include complete directory specifications in your search list definition For example to locate the file TEST DATA DAT in the device directory combinations of DISKI SMITH DISK2 STATS or DISK2 SMITH you could use the following command to define the search list TST DEFINE TST DISK1 SMITH DISK2 STATS DISK2 SMITH You can also use search lists to locate files on different devices To locate this file you specify TST TEST_DATA DAT To find the same directory and the same file name on different devices you could use the following command to define TST DEFINE TST DISK1 DISK2 DISK3 When you define the search list TST in this manner you can locate the file by using the search list to specify the device name In this way you can use a single search list to locate files that would otherwise require multiple f
49. Parse and Search Services 000 cece eens 5 26 6 1 Rooted Directory Syntax else 6 18 7 1 Designing a Pause Between Attempts to Access a Record 7 14 9 1 Specifying Run Time Attributes llle eee 9 2 9 2 Using the FDL PARSE and FDL RELEASE Routines 9 22 10 1 Using ANALYZE RMS FILE to Create a Check Report 10 2 10 2 Using ANALYZE RMS FILE to Create a Statistics Report 10 6 10 3 Examining a Sequential File 0 20 0 0c eee 10 13 10 4 Examining a Relative File 0 0 0 cee 10 16 10 5 Examining an Area Descriptor Path 00000 eee 10 18 10 6 Examining a Primary Record 0 0 eee 10 20 10 7 Examining an Alternate Record 0 00 cece eee eee 10 22 10 8 KEY and ANALYSIS_OF_KEY Sections in an FDL File 10 23 Figures 1 1 Files 11 On Disk Structure Hierarchy llli ellen 1 6 1 2 Single and Multiple File Extents llle 1 7 1 3 Tracks and Cylinders 0 2 0 0 ccc eee eee eens 1 13 1 4 DSI and FAT Structures in an XAR 2 ee 1 17 1 5 Interrecord Gaps a uo eels os S OR dos es ea FO ERR 1 19 1 6 Basic Layout of an ANSI Magnetic Tape Volume 1 21 1 7 Single File on a Single Volume 0 0 00 cece eee ees 1 24 1 8 Single File on Multiple Tape Volumes 000000 0s 1 25 1 9 Multifile Single Volume Configuration llle 1 25 1 10 Multifile Multivolume Con
50. Performance Considerations 3 5 Tuning an Indexed File If an indexed file uses only string data type keys the file is a Prolog 1 file Note The string data type keys include STRING DSTRING COLLATED and DCOLLATED keys If an indexed file uses numeric type keys it is a Prolog 2 file You cannot use the Convert Reclaim utility on a Prolog 1 file or a Prolog 2 file to reclaim empty buckets If your file undergoes a large number of deletions resulting in empty unusable buckets you must use the Convert utility CONVERT to reorganize the file Note that CONVERT establishes new RFAs for the records The compression allowed with Prolog 3 files is not possible with Prolog 1 or Prolog 2 files Prolog 3 Files Prolog 3 files can accept multiple or alternate keys and all data types including the nonstring 8 byte BIN8 and INTS8 types They also give you the option of saving space by compressing your data indexes and keys Key compression compresses the key values in the data buckets Likewise index compression compresses the key values in index buckets and data compression compresses the data portion of the records in the data buckets Key or index compression is restricted to the string key data type and the string must be at least 6 bytes in length Note You cannot use key compression or index compression with any numeric or collated key data types With key or index compression repeating leading an
51. Procedure ACP truncation RMS truncation involves resetting the end of file EOF pointer back to a previous position possibly the beginning of a sequential file to reuse the allocated space in a file RMS truncation is described in the OpenVMS Record Management Services Reference Manual under the TRUNCATE service ACP truncation occurs when RMS closes a sequential file and requests that the ACP deallocate all disk blocks allocated beyond the EOF of the file The primary use of ACP truncation is to conserve disk space The remainder of this section deals with ACP truncation You can also use ACP truncation in conjunction with large extend sizes to reduce disk fragmentation If a file is growing slowly over time the application can allocate the largest possible extend and when finished it can use ACP truncation to deallocate any unused space at the end of the sequential file However if a sequential file is continually growing excessive ACP truncation can lead to an increase in disk fragmentation resulting in more CPU and I O overhead ACP truncation can be requested directly by way of the programming interface by setting the FAB V_TEF bit on input to the 0PEN CREATE or CLOSE service The ACP truncation occurs on the close of the sequential file Note that ACP truncation can occur on shared as well as unshared sequential files If there are shared readers of the file ACP truncation is postponed until the last reader of the file clos
52. RAB V_WBH 9 3 3 Record Update Options The Update service or equivalent language statement modifies an existing record in a file Your program must first locate the appropriate record position and optionally retrieve the record itself by calling the Find or Get service or equivalent language statement The options associated with the Update service are summarized in the following table These options can be set for each Update service if the program can access the appropriate RAB control block fields The RAB control block fields are preset by connect time values or defaults and as a result of previous service calls Option Description Asynchronous record processing Record header buffer 9 20 Run Time Options Specifies that record I O for this record stream is done asynchronously e FDL CONNECT ASYNCHRONOUS e RMS RAB L_ROP RAB V_ASY Contains the symbolic address of the record header buffer that contains the fixed portion of a VFC record Applies to the Get service only e FDL None e RMS RAB L_RHB Run Time Options 9 3 Summary of Record Operation Options Option Description Record buffer address Record buffer size Specifies the address of the record buffer that contains the record to be written e FDL None e RMS RAB L_RBF Specifies the size of the records contained in the record buffer to be written e FDL None e RMS RAB W_RSZ 9 3 4 Record Deletion Options The Dele
53. RMS automatically converts the file to a Prolog 1 or Prolog 2 file Record length should reflect application requirements There is no advantage to using a record length that is based on the number of bytes in a bucket The value of the primary key must be contained within the records The records can contain either a valid key field value for the alternate keys or if you specify that null keys are allowed a field of null characters A key is a record field that identifies the record to help you retrieve the record There are two types of keys primary keys and alternate keys Data records are filed in the order of their primary key The most time efficient value for primary keys is a unique value that begins at byte 0 of the record You can allow duplicate keys in the primary index but duplicate keys may slow performance The primary key and alternate keys can be character strings or numerical values Key type is specified by the FDL attribute KEY TYPE If it is not possible to put the records into the file in order of their primary key you should specify that the buckets not be filled completely when the file is loaded If you attempt to write a record to a full bucket a bucket split occurs RMS keeps half of the records in the original bucket and moves the other records to the newly created bucket Each time a record moves to a new bucket it leaves behind a forwarding pointer called a record reference vector RRV You should avoid buck
54. Record Record Record Record Record Record Record Record Record Record ios d With Record Blocking All 10 Records Record blocking also increases the efficiency of the flow of data into the computer For example 10 unblocked records require 10 separate physical transfers while 10 records placed into a single block require only 1 physical transfer Moreover a shorter length of tape is traversed for the same amount of data thereby reducing operating time ZK 0741 GE Like disk data magnetic tape data is organized into files When you create a file on tape RMS writes a set of header labels on the tape immediately preceding the data blocks These labels contain information such as the user supplied file name creation date and expiration date Additional labels called trailer labels are also written following the file Trailer labels indicate whether or not a file extends beyond a volume boundary To access a file on tape by the file name the file system searches the tape for the header label set that contains the specified file name When the data blocks of a file or related files do not physically fit on one volume a reel of tape or a tape cartridge the file is continued on another volume creating a multivolume tape file that contains a volume set When a program accesses a volume set it searches all volumes in the set For additional information about magnetic tapes see the OpenVMS System Manager s Manual 1 3 1
55. Selection menu shows the seven scripts you can choose to help you design your file There is no default so you must explicitly select one of the scripts Choose the INDEXED script to design an indexed data file Choose a disk cluster size of three Define only one key the primary key This menu provides a selection of graphic display types Select a line plot display Select 100 000 records to be loaded initially Select the CONVERT FAST_LOAD method of loading records into the data file Opt for no additional records after the initial load Elect a fill level of 100 percent for the primary index buckets Choose the variable length record format Select an average record size of 80 characters Select an unlimited maximum record size 06000000 690000006 Select the string data type for the primary key Note The string data type keys include STRING DSTRING COLLATED and DCOLLATED keys Creating and Populating Files 4 7 Creating and Populating Files 4 1 File Creation Characteristics 606000000000606609 69 6eee 86880 Opt to disallow segmentation in the primary key Set the length of the primary key to 9 bytes Define the initial position of the primary key at column 0 Opt to disallow duplicates of the primary key Choose the Prolog 3 version Select data key compression Select data record compression Select index compression This is a line plot showing bucket size against index depth Type
56. Sort order effect on record retrieval 2 5 Spanning block boundaries stream records 2 13 Speed See Performance Spool on close option 9 12 SPRs Software Performance Reports 10 2 STATISTICS qualifier 10 6 Statistics reports 10 6 10 10 Sticky defaults for file specifications 6 8 Storage bitmap file 1 9 Stored semantics file attribute 4 19 See also File tags Storing records sequentially in a relative file 2 4 STR GETi1 DX routine 5 23 Stream record format 2 13 set of terminating characters 2 13 Stream record type 1 32 STREAM CR format 2 13 STREAM LF format 2 13 Structural level of a disk device determining 5 14 Subdirectory depths maximum 5 13 SUPERSEDE attribute 4 31 Supersede option 4 31 5 22 Surface Plot graph 4 11 A 2 Synchronous operations 8 18 SYS CVT FILENAME system service 5 8 SYS DISK logical name applied to file specification 6 2 SYS OUTPUT logical name for check report 10 1 SYS SETDDIR system service 6 13 System default extension quantity 3 5 3 7 System dependent field 1 33 System management 3 11 image activation 5 17 System parameters limiting global buffers 1 40 System resources 1 40 T Tags See File tags Tape files 1 19 Tape marks BOT 1 22 EOT 1 22 Tape processing run time options 9 13 to 9 14 TEMPORARY delete option 4 31 TEMPORARY option 4 31 Terminator characters used to delimit stream records 2 13 Index 14 Ti
57. The following file concepts are discussed in this manual e Files e Records e Fields e Bytes and bits e Access modes e Record formats e Maximum RMS file size A computer file is an organized collection of data stored on a mass storage volume and processed by a central processing unit CPU Data files are organized to accommodate the processing of data within the file by an application program The basic unit of electronic data processing is the record A record is a collection of related data that the application program processes as a functional entity For example all the information about an employee such as name street address city and state constitutes a personnel record Records are made up of fields which are sets of contiguous bytes For example a person s name or address might be a field A byte is a group of binary digits bits that are used to represent a single character You can also think of a field or an item as a group of bytes in a record that are related in some way Introduction 1 1 Introduction 1 1 File Concepts 1 2 Introduction The records in a file must be formatted uniformly That is they must conform to some defined arrangement of the record fields including the field length field location and the field data type character strings or binary integers for instance To process file data an application must know the arrangement of the record fields especially if the application intends to modif
58. access and file sharing options file specification options performance options record access options and options for e Adding records e Acting on the file after it is closed file disposition Run Time Options 9 5 Run Time Options 9 2 Options Related to Opening and Closing Files e Using indexed files e Using magnetic tapes e Performing nonstandard record processing e Maintaining data reliability 9 2 1 File Access and Sharing Options As described in Chapter 7 the program must declare the desired file access and file sharing values before opening an existing file or creating a new file and must specify record locking and buffering strategies when the file is opened These options are summarized in the next table Option Description File access File sharing Record locking Specifies the record operations that the current process performs reading records locating records deleting records adding new records updating records accessing blocks and truncating the file For additional information see Section 7 1 You specify the file access values using the FDL ACCESS primary attribute or the FAB B_FAC field Specifies the types of record operations that the current process allows other file accessors to perform reading records locating records deleting records adding new records and updating records You can also use file sharing to enable the current process to use multiple record streams or
59. an output file specification the file name field and the file type field are replaced by the corresponding related file specification fields where applicable For more information including the use of multiple related file specifications see Section 6 2 3 Device and If the device name is omitted the device field and optionally Directory the directory field accept the system logical name SYS DISK If RMS cannot translate the logical name SYS DISK to a physical device name an error occurs If the directory field does not accept the logical name SYS DISK it accepts the name of the current process default directory Primary default and related file specifications can use logical names RMS translates the primary file specification before it applies defaults and missing components RMS also translates the default file specification before using the default values Finally RMS translates the related file specification before it uses missing components supplied by the related file specification If the file specification is still missing the device or directory name components the process executing the program supplies default device and directory values The algorithm used in determining the appropriate translation is as follows if node name present then translate node name else if device name present then translate device name else if only file name present then translate file name For the remainder of this description the co
60. any kind and is subject to change without notice The warranties for Compaq products are set forth in the express limited warranty statements accompanying such products Nothing herein should be construed as constituting an additional warranty ZK4506 The Compaq OpenVMS documentation set is available on CD ROM This document was prepared using DECdocument Version 3 3 1b Contents jr ci piv Ge eh ete e Kies ee aise Shek Maw ee eyes EP xiii 1 Introduction 1 1 File Concepts ces S Se See Pan 9 Vot P pue ees ee 1 1 1 2 Disk Concepts ERE wea ERES E ERE RRRAE QR REA EE 1 3 1 2 1 Files 11 On Disk Structure Concepts lllllllln 1 6 1 2 2 Files 11 Control Files lle 1 8 1 2 2 1 Index File 3 ose cele do whey bs Ee Ree Jo ee wa a e 1 8 1 2 2 2 Storage Bit Map File llle 1 9 1 2 2 3 Bad Block Files 4 see Sh deed kx aeons dee nals Ba bod ote 1 10 1 2 2 4 Master File Directory 0 0 00 0 eee eee 1 10 1 2 2 5 Core Image Pile sis Lala ax She AAS re Ree wee Rn 1 10 1 2 2 6 Volume Set List File cee eens 1 10 1 2 2 7 Continuation File llle 1 10 1 2 2 8 Backup Log File 5o eoe band tae s aa Oe Ga Nodus 1 10 1 2 2 9 Pending Bad Block Log File 00 eee eee 1 10 1 2 2 10 Security Profiles File VAX Only 0 000 eee eee 1 11 1 2 3 Files 11 On Disk Structure Level 1 Versus Structure Level 2 1 11 1 2 4 Physical Sttuctutes 4 au iua ers aea RE ERE ERE EE
61. asynchronous record operation An operation in which your program may possibly regain control before the completion of a record retrieval or storage request Completion ASTs and the Wait service are the mechanisms provided by RMS for programs to synchronize with asynchronous record operations See also synchronous record operation bits per inch The recording density of a magnetic tape Indicates how many characters can fit on one inch of the recording surface See also density block The smallest number of consecutive bytes that RMS transfers during read and write operations A block is 512 8 bit bytes on a Files 11 On Disk Structure disk on magnetic tape a block may be anywhere from 8 to 8192 bytes block I O The set of RMS procedures that allows you direct access to the blocks of a file regardless of file organization block spanning In a sequential file the option for records to cross block boundaries bootstrap block A block in the index file of a system disk Can contain a program that loads the operating system into memory Glossary 1 Glossary 2 bucket A storage structure consisting of 1 to 32 blocks used for building and processing relative and indexed files A bucket contains one or more records or record cells Buckets are the units of contiguous transfer between RMS buffers and the disk bucket split The result of inserting records into a full bucket To minimize bucket splits RMS attempts to keep half of t
62. b rac RABSC KEY key access inrab rab 1 rop RABSM REV RABSM NXT reverse search next F inrab rab b krf 0 access by primary key inrab rab l ubf record record buffer inrab rab w usz RECORD SIZE maximum record size Open and connect status sysSopen amp infab if status amp 1 error exit status infab fab l stv status sys connect amp inrab if status amp 1 error exit status inrab rab l stv Set key larger than the largest possible real key strcpy key inrab rab l kbf key key buffer inrab rab b ksz 1 set key length Get and display the last record Status sys get amp inrab if status amp 1 error exit status inrab rab l stv record inrab rab w rsz 0 printf Record s Wn record Set key to the just read largest key inrab rab l kbf record key buffer inrab rab b ksz KEY SIZE set key length Get and display the next to last record status sys get amp inrab if status amp 1 error exit status inrab rab l stv record inrab rab w rsz N0 printf Record s n record Close file status sys close amp infab if status amp 1 error exit status infab fab l stv You can use the Find service similar to the Get service in sequential access mode random access by RFA mode or random access by key a
63. be blank RMS assigns each cell a sequential number called the relative record number that can be used to randomly access the record A relative file can contain fixed length records variable length records or VFC records Fixed length records are particularly useful in relative files because of the fixed cell size The maximum size for fixed length records in a relative file is 32 255 bytes For variable length records the maximum size is 32 253 bytes The maximum size for VFC records is 32 253 bytes minus the size of the fixed length control field which may be up to 255 bytes long Performance Considerations 3 15 Performance Considerations 3 4 Tuning a Relative File 3 4 1 Bucket Size With relative files buckets are used as the unit of transfer between the disk and memory You specify bucket size when you create the file but you can change the size later by converting the file see Chapter 10 Note that the Convert utility processes relative files by sequentially reading records from the input file then writing them to the output file As a result the relative record numbers RRN change when the input file contains deleted or unused records You can specify the bucket size using the FDL FILE secondary attribute BUCKET SIZE or by inserting the value directly into the RMS control block fields FAB B_BKS and XAB B_BKZ Although the size can be as large as 63 blocks a bucket size larger than one disk track usually does not impro
64. because extending an area generally creates a noncontiguous area extent The resulting noncontiguous extent may be anywhere on the disk and you may lose the benefits of multiple areas 3 24 Performance Considerations Performance Considerations 3 5 Tuning an Indexed File If you are using a single area for the file you should allocate enough contiguous space at creation time for the entire file If you plan to add data to the file later you should allocate extra space using the FDL attribute FILE ALLOCATION To ensure contiguous allocation set the FDL attribute FILE CONTIGUOUS to YES If you are using multiple areas you should allocate each one by specifying a value for the FDL attribute AREA ALLOCATION If the file is relatively small or if you know that it needs to be extended you do not have to use multiple areas In such cases it is more important to calculate the proper extension size To specify multiple areas using an FDL file you assign each area its own AREA primary attribute The AREA primary attribute takes as an argument a number whose value identifies the area Use the KEY attributes DATA AREA LEVEL1 INDEX AREA and INDEX _ AREA to match each area specified with its index level In the primary index structure the primary attribute KEY must take the value 0 Within the KEY 0 section you assign the DATA AREA attribute the number which identifies the data record area Then you associate the KEY LEVEL1 INDEX AREA a
65. blocks I O Techniques Deferred write Normal mode Selectable Selectable Multiblock count Yes Bucket size Bucket size Multiple access streams Yes Yes Yes Multiple buffers Yes Yes Yes Access sharing Read write Read write Read write Other features Block spanning Maximum Areas records record number The next three sections describe file organizations 2 2 4 Sequential File Organization RMS supports the sequential file organization for all device types It is the only organization supported for nondisk devices In sequential file organization records are arranged one after the other in the order in which they are stored For example the fourth record is between the third and fifth records as illustrated in Figure 2 9 Choosing a File Organization 2 15 Choosing a File Organization 2 2 File Organization Concepts Figure 2 9 Sequential File Organization Fourth Record Is Located Between Third and Fifth Records First Second Third Fourth Fifth Sixth Record Record Record Record Record Record ZK 0742 GE You cannot insert new records between existing records because no physical space separates them Therefore you can only add records to the current end of the file that is immediately following the most recently added record For the same reason you cannot add to the length of an existing record when updating it Some advantages and disadvantages of the sequential file organization are outlined in Table
66. buffers with sequential files see Section 3 3 3 For more details about using multiple buffers with relative files see Section 3 4 2 For more details about using multiple buffers with indexed files see Section 3 5 2 3 Chapter 7 describes the use of multiple buffers in the context of shared files 3 2 2 2 Deferred Write Processing One way to improve performance through minimized I O is to use the deferred write option to keep data in memory as long as practicable However you must determine if this added performance benefit is worth the increased risk of losing data if the system crashes before a buffer is transferred to disk With indexed files and relative files you may use the deferred write option to defer writing modified buckets to disk until the buffer is needed for another purpose or until the file is closed Typically the largest gains in performance come from using the deferred write option with sequential access Retrieving and modifying records one after the other permits you to access all of the records from one bucket while the bucket is in memory You may also improve performance by using the deferred write option to prevent writing a shared sequential file to disk on each modification However this increases the risk of losing data if the system crashes before the full buffer is transferred to disk Note that nonshared sequential files behave as if the deferred write option is always specified because a buffer i
67. but they are helpful in locating records during file editing At the VAX MACRO level you establish the length of the control field for VFC records using the FAB B_FSZ field in the FAB The Open Create and Display services provide the control field length in the XAB B_HSZ field of the File Header Characteristic XAB For more information see the OpenVMS Record Management Services Reference Manual When writing a VFC record to a file RMS merges the fixed length control field with the variable length record data and prefixes the merged record with the count field Figure 2 7 shows how RMS writes a VFC record to a file Figure 2 7 Writing a VFC Record to a File Fixed Control Area Portion User Action Data Portion Create Record Write Record and Prefix Count Field Count Fixed Control Area VFC Record ZK 0755 GE When RMS reads a VFC record it uses the count field to determine the overall length of the record and it uses the appropriate file attribute to determine the length of the control field After subtracting the control field length from the overall record length RMS uses the result to separate the data from the control information It then processes the data and stores the control information in a designated storage area for program use if applicable See Figure 2 8 2 12 Choosing a File Organization Choosing a File Organization 2 1 Record Concepts Figure 2 8 Retrieving a VFC Record Read Rec
68. can specify the number of buffers at run time From FDL you can set the number of buffers with the secondary CONNECT attribute MULTIBUFFER COUNT From an assembler language you can set the value directly into the RAB B_MBF field in the RAB or you can set the count using the XAB MULTIBUFFER COUNT XABITM if you want to specify more than 127 buffers From the DCL interface you can establish the number of buffers using a DCL command in the following form SET RMS_DEFAULT SEQUENTIAL DISK BUFFER_COUNT n The variable n represents the number of buffers In simple operations with sequential files one I O buffer is sufficient Increasing the number of buffers uses space in the process working set and could degrade performance With nonshared sequential files particularly if you want to perform sequential access you can use read ahead and write behind processing With this type of processing a buffer contains the next record to be read or written to the disk while a separate buffer completes the current I O operation The length of the buffers used for sequential files is determined by the specified multiblock count The optimal number of blocks per buffer depends on the record size for sequential access to a sequential file but a value such as 16 may be appropriate 3 3 4 Global Buffer Option If a file is shareable you may want to allocate it global buffers A global buffer is an I O buffer that two or more processes can access If two or
69. compared with Find service 8 2 current record and 8 16 effect on next record position 8 17 Get service cont d high level language equivalents 8 1 requirement for end of file test 8 3 run time options 9 14 to 9 18 Global buffer counts example of run time specification 5 23 to 5 25 Global buffer performance enhancements 7 24 Global buffers 1 40 3 12 3 28 number 7 19 performance 9 9 restricted use 7 23 with deferred write option 3 13 with indexed file 7 22 with relative file 7 22 with shared file 7 22 to 7 25 with shared sequential file 3 14 Global buffer sizes for shared sequential file operations 3 14 7 24 Global page tables 1 40 Global section concurrent access 7 24 Global sections 1 40 GLOBAL BUFFERS qualifier 7 23 GLOBAL BUFFER COUNT attribute 7 19 7 23 H Hard positioning option 4 36 Hardware errors 10 2 Header labels 1 22 HDR1 label 1 28 accessibility field 1 31 creation date field 1 30 expiration date field 1 30 file identifier field 1 28 file section number field 1 30 file sequence number field 1 30 file set identifier field 1 30 generation number field 1 30 generation version number field 1 30 HDR2 label 1 28 1 31 block length field 1 32 buffer offset length field 1 33 record format field 1 31 record length field 1 33 system dependent field 1 33 HDR3 label 1 28 RMS attributes field 1 34 HDR4 label 1 28 1 34 HELP comm
70. concealed or terminal use the TRANSLATION ATTRIBUTES qualifier for the DCL commands DEFINE or ASSIGN The terminal attribute indicates that the related logical name is the final name in the translation process That is no further translation is to be performed The concealed attribute ensures that RMS uses the device logical name when communicating with the application program If the device logical name does not have the concealed attribute any file specification information returned to the application program includes the device s physical name rather than its logical name To illustrate enter the following command sequence DEFINE SYSTEM USERDISK DUA5 SET DEFAULT USERDISK JONES DIRECTORY The system responds with the following display which identifies the device by its physical name DUA5 DIRECTORY DUA5 JONES FILE TXT 1 FILE TXT 2 Total of 2 files Now enter the following command sequence DEFINE SYSTEM TRANSLATE CONCEALED USERDISK DUA5 DIRECTORY The system responds with the following display which identifies the device by its logical name USERDISK DIRECTORY USERDISK JONES FILE TXT 1 FILE TXT 2 Total of 2 files A search list is a logical name that contains more than one file specification Typically a search list is used to search multiple file locations looking for a file RMS attempts to locate the file by using the first file specification in the search list then the next and so forth un
71. conversion routine such as the Convert utility to create the file again with a different organization Note that the Convert utility processes relative files by sequentially reading records from the input file then Choosing a File Organization 2 13 Choosing a File Organization 2 2 File Organization Concepts writing them to the output file As a result the relative record numbers RRN change when the input file contains deleted or unused records One of the file attributes you specify before creating a file is how records are inserted into it and subsequently retrieved from it the access mode The terms file organization and access mode are sometimes confused because they share common elements That is files are organized sequentially relative to some reference value or by keyed index value Similarly a file may be accessed sequentially relative to some reference value or by using a keyed index value The following sections emphasize the distinctions between the types of file organization Table 2 2 lists important features of each file organization Table 2 2 File Organization Characteristics Characteristics Sequential Relative Indexed Medium Disk Yes Yes Yes Magnetic tape Yes No No Unit record Yes No No Record Formats Fixed length Yes Yes Yes Variable length Yes Yes Yes VFC disk only Yes Yes No Stream disk only Yes No No Undefined disk only Yes No No Overhead Per Record 0
72. deeper than ODS 2 ISO format files read by systems that do not have ODS 2 capability such as PCs NT systems and Macintoshes Single volume with both ISO 9660 CD and Files 11 CD formats Files are accessible to both formats whose directories might point to the same data A structure that is not related to a Files 11 structure When you specify a foreign structure you make the contents of a volume known to the system but the system makes no assumptions about its file structure The application is responsible for supplying a structure lYou can mount ODS 5 enabled volumes on VAX systems but you cannot access ODS 5 specific features on a VAX system Table 1 4 compares the specific characteristics of Files 11 On Disk Structure ODS levels 1 2 and 5 Table 1 4 Comparison of ODS 1 ODS 2 and ODS 5 Levels Characteristic ODS 1 VAX only ODS 2 ODS 5 File names 9 3 Character set File versions Uppercase alphanumeric 32 767 limit version limits are not supported Directories No hierarchies of directories and subdirectories directory entries are not ordered System disk Cannot be an ODS 1 volume 39 39 Uppercase alphanumeric plus hyphen dollar sign and underscore C 32 767 limit version limits are supported Alpha 255 VAX 8 with rooted logical 16 Can be an ODS 2 volume 238 bytes including the dot For Unicode that is 119 characters includ
73. descending sort order for each key At the VAX MACRO level you encode sort order within the key data type field XAB B DTP of the associated key XAB you use the attribute KEY TYPE at the FDL level For example if you want to build an index of string data type keys in ascending sort order using VAX MACRO you enter the following line in the associated key XAB DTP STG To build an index of string data type keys in descending sort order you enter this line in the associated key XAB DTP DSTG See the OpenVMS Record Management Services Reference Manual for a complete listing of key data types used to specify ascending and descending sort order 2 2 3 5 Using Collated Keys The RMS multinational key feature lets you assign alternative non ASCII collating sequences to a key For example a program can sort records using a key that accesses a collating sequence based on French or alternatively accesses a collating sequence based on Spanish The basis for this feature is the National Character Set utility NCS When an application program creates an index file with an alternative collating sequence it calls NCS NCS responds by retrieving the collating sequence from the NCS library storing it in local memory and providing the calling program with a pointer to it In addition to naming the collating sequence the calling program must provide NCS with a location for storing the pointer CS_ID to the memory location of the collating seq
74. does not open or create a new file Instead the returned value for the internal file identifier and later the value for the internal stream identifier from a Connect service is set to indicate that access to the associated process permanent file is with the indirect subset of allowable functions The implications for the indirect accessor are described in the following list A Create service for a process permanent file becomes an Open service the fields of the FAB are output according to the description of the Open service not the Create service The Open and Create services require no I O operations Any number of indirect Open and Create operations are allowed There is only one position context for the file each sequence of the Open or Create service accesses the same record stream not an independent stream If the process permanent file was initially opened with the sequential processing only FAB V SQO bit set in the FAB L_FOP field neither random access nor the Rewind service is permitted This is the case for SYS COMMAND SYS INPUT SYS OUTPUT and SYS ERROR Certain options to various services produce errors For example you cannot set the non file structured FAB V_NFS process permanent file FAB V_ PPF and user file open FAB V_UFO bits of the FAB L_FOP field for the Open and Create services Other options are ignored such as the spool FAB V_SPL submit command file FAB V_SCF delete FAB V_DLT bits of the
75. e Blocks e Multiblocks e Buckets A block is the basic unit of disk I O and it consists of 512 contiguous bytes Even if your program requests less than a block of data RMS automatically transfers an entire block The other I O units multiblocks and buckets are made up of block multiples A multiblock is an I O unit that includes up to 127 blocks but whose use is restricted to sequential files See Section 3 3 2 for details A bucket is the I O unit for relative and indexed files and it may include up to 63 blocks See Section 3 4 and Section 3 5 for details 3 2 1 6 Multiple Areas for Indexed Files For indexed files another design strategy is to separate the file into multiple areas Each area has its own extension size initial allocation size contiguity options and bucket size You can minimize access times by precisely positioning each area on a specific volume cylinder or block For instance you can place the data area on one volume of a volume set and place the indexed area on another volume If your application is I O bound this strategy could increase its throughput You can also derive data bucket contiguity by allocating extra space for future extensions of the data area 3 2 1 7 Bucket Fill Factor for Indexed Files Any attempt to insert a record into a filled bucket results in a bucket split When a bucket split occurs RMS tries to keep half of the records including the new record if applicable in the original bucke
76. file After you have analyzed and optimized the file you can use CONVERT to create a new file having the new optimized characteristics and to copy the records in the old file Introduction 1 37 Introduction 1 7 RMS Utilities to the new file You can also use CONVERT to reformat an indexed file that has had many record insertions or deletions To invoke the Convert utility use the following DCL command line format CONVERT input filespec output filespec Use the input filespec parameter to specify the file or files you want to convert and use the output filespec parameter to specify a destination file for the converted records Figure 1 13 shows how CONVERT creates data files and loads them with converted records from an input file Figure 1 13 Using CONVERT to Create a Data File CONVERT Data File with Converted Records Input Data File ZK 0946 GE For more information about the Convert utility refer to Chapter 4 and the OpenVMS Record Management Utilities Reference Manual 1 7 3 The Convert Reclaim Utility The Convert Reclaim utility reclaims empty buckets in Prolog 3 indexed files so that new records can be added to them A bucket is a storage structure that RMS uses to build and process files The Convert Reclaim utility does an in place reorganization of the file in contrast to the Convert utility which creates a new file from the old file For this reason the Convert Reclaim utilit
77. file specification that may indicate one file or many files there is a means of testing whether one file or many files are to be processed or to explicitly disallow the use of wildcard characters for applications where only a single file should be processed To test for wildcard characters or search lists or both invoke the Parse service and test the appropriate bits in the NAM L FNB or NAML L FNB field The presence of a wildcard character usually indicates that many files should be processed depending on program conventions If a search list is present it may or may not indicate that only one file should be processed and a convention is needed for users of that program Thus by testing whether a wildcard is present the program can either invoke the Parse service once and the Search service repeatedly for each file to be opened or it can disallow wildcard characters and request that the file specification be reentered In some cases the program may need to disallow the use of a search list or allow one or many files to be accessed depending upon application conventions If you want to disallow wildcard characters invoke the Open service The Open service fails when it encounters a wildcard character Locating and Naming Files on Disks 5 29 6 Advanced Use of File Specifications This chapter is intended for readers who want to better understand how OpenVMS RMS hereafter referred to as RMS internally applies defaults parses file
78. files 2 3 Sequential files 2 15 advantages of using 2 16 allocating A 1 buffering 7 20 designing 3 13 to 3 15 disadvantages of using 2 16 examining 10 12 10 13 optimizing performance 3 13 to 3 15 read ahead and write behind 3 13 record access 8 7 8 14 tuning 3 13 to 3 15 SEQUENTIAL qualifier 7 20 SET DEFAULT command 6 13 6 14 TRANSLATION ATTRIBUTES qualifier 6 14 SET FILE EXTENSION n command 3 7 SET FILE SEMANTICS command example of tagging file 4 19 SET FILE STATISTICS command 3 29 SET FILE command ACL qualifier 4 27 GLOBAL BUFFERS qualifier 3 13 7 23 SET PROTECTION command 4 26 SET RMS DEFAULT command 3 14 BUFFER COUNT qualifier 3 11 3 14 3 16 7 20 7 21 7 22 EXTEND QUANTITY qualifier 9 7 INDEXED qualifier 7 22 RELATIVE BUFFER COUNT qualifier 3 17 RELATIVE qualifier 7 21 SEQUENTIAL qualifier 7 20 Shared access 3 3 Shared files See File sharing Shared sequential file operations establishing global buffer size 3 14 7 24 SHOW RMS DEFAULT command 3 11 3 17 current default extension size 9 7 current process default buffer count 7 20 to 7 22 SIDR secondary index data record 3 18 3 22 10 21 Signaling errors example in a VAX MACRO program 5 25 Simple characters 5 6 Single file on a single tape volume 1 24 Single file on multiple tape volumes 1 24 SIZE attribute 4 33 Index 13 Software errors 10 2 Software Performance Reports See SPRs
79. files and the data processing capabilities available to you through OpenVMS RMS referred to hereafter as RMS You should consider these factors when you write the application program especially if you have many users simultaneously accessing large files or if you have a high level of file activity where many records are stored retrieved updated or deleted in a given time period You may later reconsider these factors if you are not satisfied with the application program s performance This chapter describes file design and structure to help you make the first important design decision selecting a file organization Section 2 1 covers record access modes and formats Section 2 2 describes file concepts and organization See Chapter 3 for a description of performance criteria that will help you to evaluate the performance of your data files All of the RMS features described in this chapter are available at the VAX MACRO programming level and many are available to higher level OpenVMS programming languages that use FDL as an intermediary to the RMS control blocks See the descriptions of the FDL routines in the OpenVMS Utility Routines Manual for details High level languages may support only a subset of RMS features If you intend to use RMS from a high level language refer to your language manual to determine the RMS capabilities available to you 2 1 Record Concepts In considering the structure of your data files note that
80. fill factor of 50 means that RMS writes records in only half of each bucket when the records are first loaded leaving the remainder of the bucket empty for future write operations This fill factor minimizes the number of bucket splits The fill factor is set with the FDL attributes KEY DATA FILL and KEY INDEX _ FILL The value assigned to both attributes should be the same 3 26 Performance Considerations Performance Considerations 3 5 Tuning an Indexed File When you specify a fill factor consider the following e If the inserted records are distributed unevenly highly skewed by their primary key value then specifying a fill factor of less than 100 does not reduce the number of bucket splits e Ifthe records have key values that are close or if they are added at one end of the file many bucket splits occur anyway and the partially filled buckets in the database just waste space If this is the case you should either specify a fill factor of 100 and use the Convert utility to reorganize the file after the insertions are made or you should choose a different primary key e Ifthe inserted records are distributed fairly evenly or by their primary key then specifying a fill factor of less than 100 could significantly reduce bucket splits However the trade off is initially wasted disk space 3 5 2 3 Number of Buffers At run time you can specify the number of buffers with the FDL attribute CONNECT MULTIBUFFER_COUNT the con
81. for the file You create and modify FDL files using the Edit FDL utility EDIT FDL The Edit FDL utility contains built in design algorithms to help you optimize data file design The Edit FDL utility recognizes correct FDL syntax and informs you immediately of syntax errors You can use a text editor or the DCL command CREATE to create an FDL file but you must then follow the validity rules listed in the OpenVMS Record Management Utilities Reference Manual You can also use the Analyze RMS File utility to create FDL files from existing data files FDL files created in this manner contain special analysis sections that you can use with the Edit FDL utility to tune your data files You can use the Create FDL utility and the Convert utility to create data files from the specifications in the FDL files Note that the Convert utility processes relative files by sequentially reading records from the input file then writing them to the output file As a result the relative record numbers RRN change when the input file contains deleted or unused records By using an FDL file to create a data file from a high level language you can specify most of the creation time characteristics that are available with RMS control blocks FABs and XABs However to use all of the connect time features including wildcard characters you must use the RMS control blocks 4 2 Creating and Populating Files Creating and Populating Files 4 1 File Creation Chara
82. gap 1 18 ISO 9660 CD file format 1 4 ISO 9660 standard resolution of incompatibilities with OpenVMS 1 15 K Key 0 3 20 Key buffers 8 3 9 13 9 18 Key characteristics option 4 33 Key compression front 3 19 prohibition against using 4 8 rear 3 19 restrictions 3 2 3 19 3 26 KEY DESCRIPTOR structure 10 17 Key greater than option See Next key option Key greater than or equal option See Equal or next key option Key matches approximate 8 12 exact 8 12 generic 8 12 8 13 generic and approximate 8 13 to 8 14 Keys in records alternate 3 18 3 19 3 23 duplicate values 2 20 for Prolog 1 files and Prolog 2 files 3 19 null value 2 20 number of 3 23 primary 3 20 3 23 segmented 3 20 size 9 13 9 16 9 18 used in storing indexed records sequentially 2 5 Keys of reference 2 5 KEY GREATER EQUAL attribute 8 8 8 9 KEY GREATER THAN attribute 8 8 8 9 L Labels ANSI magnetic tape 1 19 1 22 EOF end of file 1 34 EOV end of volume 1 34 HDR1 1 28 HDR2 1 31 HDRS3 1 34 HDR4 1 34 header 1 27 ISO 1 19 Labels cont d trailer 1 34 VOLI 1 24 Leading hyphens file names 5 10 subdirectory names 5 10 Leading zeros in stream records 2 13 LEVEL1 INDEX AREA attribute 3 25 LIB FIND FILE routine 5 21 to 5 25 LIB STOP routine 5 25 Line Plot graph 4 11 A 2 Local nodes 5 3 Locate mode record retrieval and 8 2 Lock mastering nodes 3 33 Lock requesti
83. hierarchical organization of files their data and the directories needed to gain access to them The OpenVMS file system implements the Files 11 on disk structure and provides random access to the files located on the disk or CD ROM Users can read from and write to disks Users can read from and write to disks They can read from CD ROMs and if they have a CD Recordable CD R or CD RW drive they can write or burn their own CD ROMs On disk structures include levels 1 2 and 5 Levels 3 and 4 are internal names for ISO and High Sierra CD formats ODS 1 and ODS 2 structures have been available on OpenVMS systems for some time Beginning with OpenVMS Version 7 2 on Alpha systems you can also specify ODS 5 to format disks Table 1 3 compares the characteristics of file structures that are available on OpenVMS Version 7 2 and later systems Introduction 1 3 Introduction 1 2 Disk Concepts Table 1 3 File Structure Options on OpenVMS Systems Structure Disk or CD Description ODS 1 ODS 2 ODS 5 ISO 9660 CD Dual format Foreign Both Both Both CD CD Both VAX only use for RSX compatibility RSX 11M RSX 11D RSX 11M PLUS and IAS operating systems Default disk structure of the OpenVMS operating system use to share data between VAX and Alpha with full compatibility Alpha only superset of ODS 2 use when working with systems like NT that need expanded character sets or directories
84. in Pascal Record Processing 8 1 Record Processing 8 2 Primary Services Update The Update service modifies an existing disk file record The Update service corresponds to the UPDATE statement in BASIC and Pascal and to the REWRITE statement in COBOL Fortran and PL I Delete The Delete service erases records from relative disk files and indexed disk files The Delete service corresponds to the DELETE statement in BASIC COBOL Fortran Pascal and PL I A single statement in a high level language may correspond to one or several RMS record processing service calls For example the COBOL statement DELETE uses the Delete service during sequential record access but it uses the Find and Delete services during random record access File organization in part determines the types of record operations that a program can perform Table 8 1 shows the major record operations that RMS permits for each file organization Table 8 1 Record Operations and File Organizations Record Operation Bronson Permitted Sequential Relative Indexed Get Yes Yes Yes Put Yes Yes Yes Find Yes Yes Yes Delete No Yes Yes Update Yes Yes Yes lIn a sequential file RMS allows records to be added at the end of the file only Records can be written to other points in the file by using a Put service with the update if option When performing an Update service to a sequential file containing fixed length records you cannot change the length of the re
85. in an error And you cannot create a directory using a DID 6 5 FID Abbreviated Names Alpha Only On Alpha systems when a file specification even with DID abbreviation is too long to fit into a resultant name buffer NAM block NAM L_RSA field or NAML block NAML L RSA field RMS attempts to generate a short enough file specification by identifying the file with its file ID three decimal numbers separated by commas surrounded by brackets in the file name component In cases in which the file type component would otherwise be presented a generated file specification will either include the entire type or will not include any type including the delimiter depending upon whether or not there is space In cases in which the version component would otherwise be presented a generated file specification will include the version component As a human readable aid in recognizing files when a FID is generated the name component also contains a DCL legal initial subset of the actual file name The subset consists of the first 38 simple characters where U1234 is six simple characters of the actual file name followed by 6 20 Advanced Use of File Specifications Advanced Use of File Specifications 6 5 FID Abbreviated Names Alpha Only No attempt is made to resolve ambiguities for files that differ only after the first 38 simple characters of their names An example of a generated name with a FID is as follows DKA200 S
86. intend to add small amounts of data to a file over a long time smaller file extends can avoid wasted disk space 3 4 Performance Considerations Performance Considerations 3 2 Tuning There are two methods for extending files One method is for an application program to call the EXTEND service see the OpenVMS Record Management Services Reference Manual for details When it calls the EXTEND service the application must specify an explicit extend size in disk blocks because no defaults are used to determine the extend size The other method is for RMS to automatically extend auto extend a file when free space is needed You can specify the size of auto extends using various default extension quantities or you can have RMS supply a default extend size However when RMS supplies a default it uses an algorithm that allocates a minimal extend Repeated minimal extends can increase file fragmentation 3 2 1 3 1 Auto Extend Size Selection This section describes the factors used to determine the size of auto extends These include e File organization sequential relative and indexed e Type of access record I O or block I O e Various default extension quantities The remainder of this section describes how to use the various default extension quantities to select the auto extend size for all file organizations and access types Manipulatiing the various default extension quantities is described in Section 3 2 1 3 2 Sequential Fi
87. is only meaningful to the application assigning it Having enabled RMS statistics the system manager runs the application and then uses the DCL interface to periodically display the statistics using the following command MONITOR RMS FILE DATABASE DAT ITEM CACHING 3 30 Performance Considerations Performance Considerations 3 6 Monitoring RMS Performance The Monitor utility responds with information displays similar to the following VAX VMS Monitor Utility RMS CACHE STATISTICS on node MENASH 28 FEB 1994 16 03 59 Index MENASHSDUAO TOREP DATABASE DAT 1 Active Streams 60 CUR AVE MIN MAX Local Cache Hit Percent 40 00 59 86 38 00 80 00 Local Cache Attempt Rate 59 81 59 26 56 07 60 55 Global Cache Hit Percent 87 54 81 38 57 43 100 00 Global Cache Attempt Rate 23 36 14 88 7 47 23 85 Global Buf Read I O Rate 0 00 1 21 0 00 2 91 Global Buf Write I O Rate 0 00 0 00 0 00 0 00 Local Buf Read I O Rate 12 14 8 84 4 67 13 08 Local Buf Write I O Rate 29 90 29 63 28 97 29 90 Interpretation of RMS cache statistics depends in great part on the application and file organization The file type Index is noted on the display immediately preceding the file specification The MONITOR display illustrated here is limited to the activity on a single node MENASH To obtain a clusterwide view of RMS activity you must run the Monitor utility using the RECORD qualifier on all cluster nodes that access the file You can then analyze the result
88. maintaining a lock on the first record By using manual unlocking the application program can restore the original contents of the first record if the update to the second record fails thereby maintaining data integrity 7 2 4 2 Lock Nonexistent Record Option The lock nonexistent record option applies only to random accessing of relative files Relative files have a static physical structure made up of record cells in contrast to sequential files and indexed files which have a dynamic structure The record cells may or may not contain records A record may have been deleted from a cell or the cell may be empty that is it never contained a record In either case the record cells are accessible to the application program Typically if a record stream tries to access and lock an empty cell in a relative file using random access the accessing service returns a record not found error status RMS RNF However if the lock nonexistent record option is selected the accessing service returns an alternative success status RMS OK RNF indicating that the record stream accessed a cell that never contained a record If the cell contains a deleted record RMS returns the deleted record with an alternate success status RMS OK DEL to indicate that a deleted record was accessed The lock nonexistent record option prevents other record streams from putting a record into an empty cell until the locking record stream puts a record in it or relea
89. memory or disk drives to ensure that sufficient system resources are available 1 8 1 Memory Requirements One of the most important ways to improve application performance is to allocate larger buffer areas or more buffers for an application As described in Chapter 7 the number of buffers and the size of buckets and blocks can be fine tuned on the basis of the way the file will be accessed For indexed files the index structure and other factors must also be considered When a file is opened or created RMS maintains the buffers and control structures charged to process memory use Memory use generally increases with the number of files to be processed at the same time The amount of memory needed for I O buffers can vary greatly for each file but the amount of memory needed for control structures is fairly constant The memory use working set of a process is governed by three resource limits e Working set default WSDEFAULT e Working set quota WSQUOTA e Working set extent WSEXTENT These values can ensure that the process has sufficient memory to perform the application with minimum paging For a complete description of these limits see the OpenVMS System Manager s Manual In addition to process requirements you may want a shared file to use global buffers to avoid needless I O when the desired buffer is already in memory Global buffer usage is limited by the following system parameters e RMS global buffer quota RMS_GB
90. next two sections explain how to use the Convert utility to populate a file 4 5 1 Using the Convert Utility The Convert utility allows you to create and populate a file To create a file you need an input data file and an FDL file that describes the output file you want to create You issue a DCL command in the following form CONVERT CREATE FDL fdl file input file output file As with the CREATE FDL command the CONVERT CREATE FDL command creates a file named by the output file parameter and having characteristics specified in your FDL file Unlike the CREATE FDL command CONVERT populates the output file with the records from the input file For example to create the file CUST IDX from the specifications in the FDL file STDINDEX FDL and copy the records from the input file CUST SEQ into CUST IDX you enter the following command CONVERT CREATE FDL STDINDEX FDL CUST SEQ CUST IDX RMS assigns the characteristics specified in the file STDINDEX FDL to the records in CUST IDX Note that the Convert utility processes relative files by sequentially reading records from the input file then writing them to the output file As a result the relative record numbers RRN change when the input file contains deleted or unused records 4 5 2 Using the Convert Routines You can invoke the functions of the Convert utility from your application program by calling the following series of convert routines CONV PASS FILES Names the files to be conv
91. not found an I O operation occurs When using the deferred write option with global buffering enabled the number of buckets that can be buffered without I O is equal to the number of local buffers thus the use of more than the minimum number of local buffers should be considered You can specify the number of global buffers two ways by using a preset file default or by having the first process that accesses the file specify the value at run time To set the file default maintained in the file header use the DCL command SET FILE GLOBAL BUFFERS n where n is the number of buffers To set the global buffer value at run time the first process to connect to the file with the FILE GLOBAL BUFFER COUNT attribute FAB field FAB W_GBC greater than 0 can set this value The default value returned in the FAB W GBC field following an Open or Create service may be altered if unacceptable before invoking the Connect service When a previous or subsequent application program attempts to open and connect to the file the global buffer count File Sharing and Buffering 7 23 File Sharing and Buffering 7 3 Local and Shared Buffering Techniques determines whether or not that process uses global buffers If the value is 0 that process uses only local buffers if the value is greater than 0 that process uses global buffers along with other processes Refer to the OpenVMS Record Management Services Reference Manual for additional information on the use of
92. order is derived from search list Y 1 DISK1 RED 2 DISK2 WHITE 3 DISK1 BLUE When opening a file RMS tries all search list possibilities before it signals an error completion status If RMS cannot find the file it displays where applicable the final search list file specification and the error message When RMS tries to locate a file using multiple search lists it uses all combinations of the elements in the search lists First it combines the first entry in the first list with the first entry in the second list Then it combines the first entry in the first list with the second entry in the second list After trying all combinations of the first entry in the first list with all entries in the second list RMS repeats the exercise using the entries in the second list with the second entry in the first list This continues until RMS locates the file or until it tries all combinations of all lists For example assume the program is looking for FILE DAT which may be in one of two directories BIG or BEST on one of two disks DISK1 or DISK2 First the program defines two search lists a disk search list PRIM and a directory search list DEF DEFINE PRIM DISK1 DISK2 DEFINE DEF BIG BEST Next the program provides a primary file specification that includes the search list PRIM for the disk together with the file name component PRIM FILE Advanced Use of File Specifications 6 7 Advanced Use of File Speci
93. period to the left of the version if any begins the type component Locating and Naming Files on Disks 5 9 Locating and Naming Files on Disks 5 2 File Specification Components e No periods other than the type and version delimiters are allowed 5 2 8 Leading Hyphens in File and Subdirectory Names Alpha Only On Alpha systems OpenVMS Version 7 2 supports the use of file names and subdirectory names that begin with hyphens This is supported on ODS 5 and ODS 2 disks No special action is required for specifying a name that begins with a hyphen with the following exception A reference to a subdirectory whose name consists only of hyphens must include at least one escaped hyphen so that RMS can distinguish the reference from a relative directory specification On output RMS always displays such a subdirectory name with the first hyphen escaped For example SCREATE DIRECTORY DISK SCREATE DIRECTORY DISK FLARKY LEVELl LEVEL2 LEVEL3 SSET DEFAULT DISKS FLARKY LEVEL1 LEVEL2 LEVEL3 SWRITE SYSSOUTPUT F PARSE relative spec DISK FLARKY WRITE SYSSOUTPUT F PARSE directory DISK WRITE SYSSOUTPUT FSPARSE directory DISK SDIRECTORY NOHEADING NOTRAILING DISK 000000 DIR DISK 000000 DIR 1 file DIR Note OpenVMS Version 7 2 for VAX and versions of OpenVMS prior to Version 7 2 do not support file and subdirectory name
94. prefix XAB For more information about RMS control blocks see Chapter 4 1 6 3 Record Management Services Because RMS performs operations related to files and records services generally fall into one of two groups e Services that support file processing These services create and access new files access or open previously created files extend the disk space allocated to files close files get file characteristics and perform other functions related to the file e Services that support record processing These services get extract find locate put insert update modify and delete remove records and perform other record operations For more information about the various services see Chapter 7 and Chapter 8 1 36 Introduction Introduction 1 7 RMS Utilities 1 7 RMS Utilities The following are RMS file related utilities e The Analyze RMS_File utility e The Convert utility e The Convert Reclaim utility e The Create FDL utility e The Edit FDL utility These utilities let you design create populate maintain and analyze data files that can use the full set of RMS create time and run time options They help you create efficient files that use a minimum amount of system resources while decreasing I O time For more information about the record management utilities see the OpenVMS Record Management Utilities Reference Manual 1 7 1 The Analyze RMS File Utility With the Analyze RMS File utility ANALYZE RM
95. quantity in one of the following Ways After a file has been created specifying the file default extension quantities FAB W DEQ on input to a OPEN establishes a temporary file default extension quantity that overrides any permanent setting that might exist This temporary default is used when you access the file until the file is closed Note that the area default extension quantities for an indexed file specified on a CREATE cannot be changed over the lifetime of the file nor can they be overridden at run time Once a file has been created you can change or establish the permanent file default extension quantity by using the DCL command SET FILE EXTENSION n where n is the extension quantity in disk blocks for the file The next time the file is opened it uses the new default quantity In addition to the file and area default extension quantities there are process system and volume default extension quantities Process Default Extension Quantity The process default extension quantity is established by the DCL command SET RMS DEFAULT EXTEND QUANTITY n where n is the extension quantity This default applies only to the process issuing this DCL command and remains in effect only until the process is deleted System Default Extension Quantity The system default extension quantity is established by the SET RMS DEFAULT SYSTEM EXTEND_QUANTITY n command Note that you need the CMKRNL privilege to use the SYSTEM qualifier
96. related blocks of data might include the contents of a file or several files that are accessed together by a performance critical application Another physical disk structure is called a cylinder A cylinder consists of all tracks at the same radius on all recording surfaces of a disk Figure 1 3 illustrates the relationship between tracks and cylinders 1 12 Introduction Introduction 1 2 Disk Concepts Figure 1 3 Tracks and Cylinders A track is comprised of the area at a single radius on one recording surface l A cylinder consists of I these tracks in the same radius on all the recording surfaces Recording occurs on both surfaces of each platter The extreme top and bottom surfaces of some disk models are not used for recording _ A A I Remainder of volume containing other cylinders I pinum e A DOE EL ae ZK 0740 GE Because all blocks in a cylinder can be accessed without moving the disk s read and write heads it is generally advantageous to keep related blocks in the same cylinder For this reason when choosing a cluster size for a large capacity disk a system manager should consider one that divides evenly into the cylinder size Introduction 1 13 Introduction 1 2 Disk Concepts 1 2 5 CD ROM Concepts This section describes software support for accessing CD ROM media in compliance with the ISO 9660 standard Compact Disc Read Only Mem
97. related name blocks 6 8 Advanced Use of File Specifications Advanced Use of File Specifications 6 2 Understanding RMS Parsing is especially useful for search lists one related name block might contain a file type that can be used by any file specification in a search list another might contain the full file specification that was produced by the first search list file specification and another might contain the full file specification produced by the second search list file specification This method allows the file specifications in a search list to provide sticky defaults a characteristic associated with DCL command lines that contain multiple file specifications For a search list to be applied as a related file specification the related file specification must not be a resultant string but must include the search list logical name The related file specification in this case must describe the original primary file specification For example consider the following search list definition DEFINE WORK DISK1 MINE DISK2 GROUP To process lists of input files such as WORK A B C your program must supply the string WORK A as the related file specification not DISK2 GROUP A DAT The routines LIB FIND_FILE and LIB FILE_SCAN are provided to perform this special processing consult the OpenVMS RTL Library LIB Manual for additional information also refer to Example 5 2 which shows how to call the LIB FIND_FILE routine 6
98. sequential file can update their internal end of file context by closing and reopening the file No form of record locking is supported for this type of file sharing Although record locking is not checked using user interlocked interprocess file sharing file locking is checked For instance if you or another user specify SHARING NONE one of you may be denied access If a process tries to implement the truncate service when closing a sequential file it must have sole write access to the file If other processes have write access to the file RMS does not close it and it remains accessible to other processes If other processes have the file open for read access RMS defers the truncation until the final process having read access closes the file Similarly if a process tries to implement the truncate on put option when inserting a record into a sequential file it must have sole access to the file If other processes have access to the file RMS does not insert the record 7 2 Record Locking Synchronized access to records is required in a shared file environment where record streams may compete for access to records The operating system implements synchronized access using record locking That is record access conflicts are resolved by locking the record until the final competing record stream processes the record This ensures that a program may add delete or modify records without interference and that when a record operation is finis
99. series of blocks For relative and indexed organizations RMS reads and writes buckets The relationship between the application program and the I O buffers that RMS maintains is shown in Figure 7 2 As illustrated the application program resides in the PO region of process address space The RMS maintained buffer area together with RMS maintained control information resides in the P1 region Note that RMS normally overflows into PO space and that the linker provides options for controlling the overflow Note too that linker options are available for allocating additional buffer space in the PO region if needed See the OpenVMS Linker Utility Manual for details 7 18 File Sharing and Buffering File Sharing and Buffering 7 3 Local and Shared Buffering Techniques Figure 7 2 RMS Buffers and the Application Program Process Virtual Memory User Program Image PO Space User Record Buffer Program Region Records RMS Buffer P1 Space Control Region System Control Information Blocks or y Buckets ZK 1993 GE The specified record buffer contains the record to be read or written and RMS maintains the rest of the block in application program process space in an RMS controlled area of the program For optimum performance consider the number of buffers carefully The defaults calculated by RMS are few and may be adequate for access to small files For example it is not unusual to specify many buffers when processing a
100. sizes and number of buffers When you add records to an indexed file consider choosing the deferred write option FDL attribute FILE DEFERRED_WRITE FAB L_FOP field FAB V_ DFW With this option the buffer into which the records have been moved is not written to disk until the buffer is needed for other purposes the Flush service is used or until the file is closed The deferred write option however may cause records to be lost if a system crashes before RMS transfers the records to the disk In general you must consider several trade offs when you set the number of buffers your application needs e CPU time e Availability of memory and number of page faults e I O operations Performance Considerations 3 27 Performance Considerations 3 5 Tuning an Indexed File With indexed files buckets not blocks are the units of transfer between the disk and memory You specify the bucket size when you create the file although you can change the bucket size of an existing file with the Convert utility see Chapter 10 3 5 2 4 Global Buffers If several processes share the indexed file concurrently you may want to specify that the file use global buffers A global buffer is an I O buffer that two or more processes can access If two or more processes request the same information from a file each process can use the global buffers instead of allocating its own Only one copy of the buffers resides at any one time in memory although the
101. specifications and handles directory specifications This chapter also describes the use of rooted directory syntax and process permanent files 6 1 How RMS Applies Defaults This section describes how RMS applies defaults when it parses specifications supplied by your program Several file specifications can be used by RMS s Parse operation to compose a fully qualified expanded file specification which can then be used for operations such as searching for a specific file opening an existing file or creating a new file The program supplied file specifications are the primary file specification the default file specification and one or more related file specifications RMS also uses the process default file specification but it is not supplied by the program The program accepts from the user a file specification and passes it to RMS as the primary file specification The program provides to RMS through the default file specification components that RMS can use in place of missing components in the primary specification and that are related to the program s function rather than to the files being operated on Typically the default file specification contains a default for the type component for example DAT to specify a data file or TXT to specify a text file or it contains default device and directory components The related file specification is used when two files are involved in an operation such as copying or merging fi
102. system implements Files 11 ODS 1 on VAX systems only and Files 11 ODS 2 on VAX and Alpha systems to define the disk structure and to provide access to the files located on magnetic disks This section describes the Files 11 ODS levels and defines related terminology See Section 1 2 5 for information about concepts and logical structures used with CD ROMs formatted in accordance with ISO 9660 The primary difference between Files 11 ODS 1 and Files 11 ODS 2 is that Files 11 ODS 2 incorporates control capabilities that permit added features including volume sets described later The logical ordering of ODS structures is listed below in order of ascending hierarchy e Blocks e Clusters e Extents e Files e Volumes e Volume Sets Figure 1 1 shows the hierarchy of blocks clusters extents and files in the Files 11 ODS Figure 1 1 Files 11 On Disk Structure Hierarchy Extent 1 Extent 2 Extent 3 Cluster 1A Cluster 1B Cluster 1C Cluster 2A Cluster 3A Cluster 3B zz Block Block Block Block Block Block Block Block Block Block Block Block 1 6 Introduction ZK 0739 GE The next higher level of Files 11 ODS is the volume not illustrated which is the ordered set of blocks that comprise a disk However a volume may include several disks that together make up a s
103. that you can access or that can inhibit access to a volume and its files on OpenVMS systems Volume Identifier Field The volume identifier field is a 6 character field that contains the name of the volume You specify the volume identifier in the command string when you initialize or mount a volume see the OpenVMS System Manager s Manual The volume identifier consists of six ASCII a characters Lowercase characters are not in the a set but if you specify them OpenVMS systems change them to uppercase If you specify fewer than six characters OpenVMS systems pad the field by right justifying the field with the ASCII space character Accessibility Field The accessibility field is a one character field that allows an installation to control access to a volume See the OpenVMS System Manager s Manual for a description of accessibility support Implementation Identifier Field The implementation identifier field contains the identifier of the implementation that creates the magnetic tape This field controls how certain implementation specific fields and volume labels are interpreted The magnetic tape file system s implementation identifier is DECFILE11 A This field contains the implementation identifier only if a second volume VOL2 label is written on the magnetic tape Otherwise it is filled with ASCII space characters Owner Identifier Field The owner identifier field is available to the user This field does not affect t
104. the FAB W_GBC field and Connect service An example of a routine that sets the global buffer count after opening a file is provided in Example 5 2 To request that the global buffer cache be read only specify SHARING GET and SHARING MULTISTREAMING attributes FAB B_SHR field FAB V_SHRGET and FAB V_MSE When modifying an application program to use global buffers consider using more global buffers and slightly larger bucket sizes if records are processed randomly For application programs with many users consider allocating a number of global buffers equal to the number of local buffers used previously multiplied by number of users if resources permit No Global Buffers No Local Buffers x Average No Users When using an indexed file if the index structure is small and the number of users is many consider allocating enough global buffers to keep the entire index structure in memory For shared sequential file operations the first accessor of the file uses the multiblock count value to establish the global buffer size for all subsequent accessors 7 3 6 4 Enhancing Global Buffer Performance OpenVMS includes enhancements that improve RMS global buffer performance These features are greater scalability greater concurrent access to the global section and read mode bucket locking for shared access to global buffers Greater Scalability RMS implements an algorithm for global buffer management that dramatically improves scalabil
105. the case of a related file specification you may choose either the asterisk or the ellipsis but not both in the output directory specification unless you use the following form 5 3 6 10 Advanced Use of File Specifications Advanced Use of File Specifications 6 2 Understanding RMS Parsing A subdirectory specification that contains wildcard characters cannot be followed by a subdirectory specification that does not contain wildcard characters e Specifications in the UIC directory format may receive defaults only from directories in the UIC directory format e Specifications in the non UIC directory format may receive defaults only from directories in the non UIC directory format e Specifications in the non UIC directory format that consist entirely of wildcard characters may receive related file specification defaults from directories in UIC or non UIC format RMS processes wildcard characters in an output directory specification as follows e Ifyou specify an output directory using a specification that consists entirely of wildcard characters only and are allowed RMS accepts the complete directory component from the related file specification This permits you to duplicate an entire directory specification e If you specify an output directory with a trailing asterisk for example A B RMS substitutes the first wild subdirectory from the related file specification This substitution permits you to
106. the following data types e A single contiguous character string e A packed decimal number e A 2 4 or 8 byte unsigned binary number e A 2 4 or 8 byte signed integer Note RMS 11 cannot process 8 byte numeric keys Segmented keys are fields of character strings having from 2 to 8 segments that may be or may not be contiguous however RMS treats all key segments as a logically contiguous string Segmented keys enhance flexibility in manipulating data files by letting you select the placement of data fields and then tailoring the key structure to fit this layout You can improve performance by defining a segment that contains the desired key together with another segment that contains a unique field thereby making the entire key unique When only noncontiguous portions of a text string are needed for a key you can improve efficiency by defining smaller keys that include only these segments For an indexed file you must define at least one key the primary key and you can optionally define one or more alternate keys RMS uses alternate keys to build indexes that identify records in alternate sort orders As with the primary key each alternate key is defined by location and length 2 2 3 3 Other Key Characteristics In addition to defining keys you can specify various key characteristics FDL secondary key attributes including the following Duplicate keys This characteristic permits you to use the key value in more
107. the trailing period ROOT1 indicates that a root directory is present DEFINE TRANSLATION ATTR CONCEALED BASE DUA7 ROOT1 SET DEFAULT BASE SUB DIRECTORY DIR DIR The system responds with the following display BASE SUB SUBSUB DIR BASE 000000 SUB DIR In the preceding example the SET DEFAULT command defines the process default directory as ROOT1 SUB using the rooted device logical name BASE The DIRECTORY command looks for directory files in the current directory ROOTI SUB and then in the directory directly above it ROOT1 The directory ROOT1 SUB is listed by the DIRECTORY command as a top level directory BASE SUB and the root directory is listed using the syntax of the MFD BASE 000000 6 3 4 Concatenating Rooted Directory Specifications When it concatenates specifications for rooted directories RMS uses different syntax rules than it uses when it concatenates directory specifications for normal directory syntax One difference between the two conventions is associated with the trailing period in the root directory definition For example consider how a top level directory reference is handled With rooted directory syntax the root directory s trailing period is implied as a leading period in subsequent rooted directory references Advanced Use of File Specifications 6 15 Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concatenation Directory
108. time the run down control routine ensures that the indirect I O on process permanent files terminates however these files are not closed 6 22 Advanced Use of File Specifications Advanced Use of File Specifications 6 6 Using Process Permanent Files e All file organizations may be opened directly as process permanent files for example through the DCL command OPEN but only those files with a sequential organization may be indirectly accessed Advanced Use of File Specifications 6 23 7 File Sharing and Buffering This chapter discusses the run time options that are available when opening connecting and closing a shared file These options are implicit in creating a shared file because the Create service includes an implied file open File sharing includes file accessing record locking and local and shared buffering Figure 7 1 shows a typical shared file situation Figure 7 1 Shared File Access ZK 0757 GE See the OpenVMS Record Management Services Reference Manual for more information about accessing and sharing files 7 1 File Accessing OpenVMS RMS hereafter referred to as RMS file sharing allows multiple users to access a single file Timely access to files sometimes requires that more than one active program be allowed to read write and modify records within the same file simultaneously Whether or not a file can be shared depends on the type of device it resides on and the explicit file sharing infor
109. to build the primary index See also key indexed file and alternate key random access by key indexed file Retrieval of a data record in an indexed file by either a primary or alternate key within the data record See also key indexed file random access by key relative file Retrieval of a data record in a relative file by the relative record number of the record See also key relative files random access by record file address RFA Retrieval of a record by the record s unique address which RMS returns to you This record access mode is the only means of randomly accessing a sequential file containing variable length records random access by relative record number Retrieval of a record by its relative record number For relative files and sequential files on disk devices that contain fixed length records random access by relative record number is synonymous with random access by key See also random access by key relative files only and relative record number read ahead processing A software option used for sequentially accessing sequential files using two buffers One buffer holds records to be read from the disk The other buffer awaits I O completion record A set of related data that your program treats as a unit record access mode The manner in which RMS retrieves or stores records in a file Available record access modes are determined by the file organization and specified by your program record a
110. to locate the desired record This access mode is supported for all three file organizations and is normally available only to programs written in VAX MACRO or similar low level languages Record access is specified using language statements or by establishing the appropriate control block field values not offset values in the RAB Note No FDL attributes are provided for specifying record access The appropriate RAB values in the access mode specification field identified by the symbolic offset RAB B RAC are as follows e You specify sequential access by inserting the value RAB C SEQ in the RAB B RAC field e You specify either random access by key or random access by relative record number by inserting the value RAB C KEY in the RAB B_RAC field This access mode is used to randomly access records in indexed files using a specified key value It is also used to randomly access records by record number in relative files and in sequential files having fixed length records e You specify random access by RFA for all file organizations by inserting the value RAB C RFA in the RAB B_RAC field Your program may also need to specify the key or other record identifier needed to access the records For indexed files there are additional key related options The record access mode can be changed without reopening the file or reconnecting the record stream For example you can use random access by key to establish the current rec
111. upon a specialized language provided as an alternative to using RMS control blocks directly the File Definition Language FDL If you use a low level language you can either use record management services directly or you may use FDL 1 6 1 File Definition Language FDL FDL is a special purpose language you can use to specify file characteristics FDL is particularly useful when you are using a high level language or when you want to ensure that you create properly tuned files Properly tuned files can be created from an existing file or from a new design for a file The performance benefits of properly tuned files can greatly affect application and system performance especially when using large indexed files Introduction 1 35 Introduction 1 6 RMS Record Management Services FDL allows you to use all of the creation time capabilities and many of the run time capabilities of RMS control blocks including the file access block FAB the record access block RAB and the extended attribute blocks XABs For more information about FDL see Section 4 1 2 1 6 2 RMS Data Structures RMS control blocks generally fall into two groups those pertaining to files and those pertaining to records To exchange file related information with file services you use a control block called a file access block FAB You use the FAB to define file characteristics file specifications and various run time options The FAB has a number of fi
112. use several methods to randomly access a record by key e Exact match of key values e Approximate match of key values When accessing an index in ascending sort order RMS returns the record that has the next higher key value Conversely when it accesses the index in descending sort order RMS returns the record that has the next lower key value e Generic match of key values Applies to string data type keys only STRING DSTRING COLLATED and DCOLLATED For a generic match the program need specify only a match of some specified number of leading characters in the key e Combination of approximate and generic match Chapter 8 describes these key match conditions in more detail 2 6 Choosing a File Organization Choosing a File Organization 2 1 Record Concepts In contrast to record retrieval requests program requests to store records randomly in an indexed file do not require the separate specification of a key value All keys primary and any alternate key values are in the record itself When your program opens an indexed file to store a new record RMS uses the key definitions in the file to find each key field in the record and to determine the length of each key After writing the new record into the file RMS uses the record s key values to make appropriate entries in the related indexes so that the record can be accessed subsequently using any of its key values 2 1 1 3 Random Access by Record File Address Every record
113. used 0 astprm not used 0 nullarg not used if status amp 1 1 status iosb iosb w status If the call succeeded get the status value from the queued request if status amp 1 If success SWitch ACP typeBuffer case DVISC ACP F11V1 printf On disk structure level of disk device s is 1 n deviceName break case DVISC ACP F11V2 printf On disk structure level of disk device s is 2 n deviceName break case DVISC ACP F11V5 printf On disk structure level of disk device s is 5 n deviceName break default printf Device s is not of a recognized on disk structure level n deviceName printf ACP type code is 8 8X Mn ACP typeBuffer break end of switch ACP typeBuffer end of if status amp 1 else Call or queued request failed lib signal status signal exception end of main 5 16 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 4 File Specification and Component Length Limits 5 4 6 Using File Specification Defaults When you omit file specification components except for the node name and root name RMS supplies default values for the missing components The file specification to which defaults are applied is called the primary file specification Your program can supply default values for all file specification components using either the default file specification or the related file specification
114. used to write file creation and run time specifications for data files These specifications are written in text files called FDL files they are then used by the RMS utilities and library routines to create the actual data files file header A block in the index file describing a file on a Files 11 On Disk Structure disk including the location of the file s extents There is at least one file header for every file on the disk file organization The physical arrangement of data in the file You select the specific organization from those offered by RMS based on your individual needs for efficient data storage and retrieval See also indexed file organization relative file organization and sequential file organization Files 11 On Disk Structure The standard physical disk structure used by RMS fixed length control field A fixed size area prefixed to a VFC record containing additional information that can be processed separately and that may have no direct relationship to the other contents of the record For example the fixed length control field might contain line sequence numbers for use in editing operations fixed length record format Property of a file in which all records are the same length This format provides simplicity in determining the exact location of a record in the file and eliminates the need to prefix a record size field to each record global buffer A buffer that many processes share home block A b
115. will be interchanged to systems that do not process HDR3 labels correctly The RMS attributes describe the record format of a file These attributes are converted from 32 bytes of binary values to 64 bytes of ASCII representations of their hexadecimal equivalents for storage in the HDR3 label 1 3 1 6 4 HDR4 Label The HDR4 label contains the remainder of an OpenVMS file name that would not fit in the HDR1 file identifier field Labels The operating system supports two sets of trailer labels end of file EOF and end of volume EOV A trailer label is written for each header label EOF and EOV labels are identical to their file header label counterparts except that e The label identifier field characters 1 3 contains EOF or EOV e The block count field characters 55 60 in the EOF1 and EOV1 labels contains the number of data blocks in the file section The particular label that OpenVMS systems write depends on whether a file extends beyond a volume If a file terminates within the limits of a volume EOF labels are written to delimit the file see Figure 1 7 If a file extends across volume boundaries before terminating EOV labels are written indicating that the file continues on another volume see Figure 1 8 Command Procedures to Perform Routine File and Device Operations Many of the operations that you perform on disk and magnetic tape media are routine in nature Therefore you will find it worthwhile to take the t
116. with the file access and the Open service returns the file s stored attributes to the accessing program regardless of whether the program senses tags 4 22 Creating and Populating Files Creating and Populating Files 4 3 Creating and Accessing Tagged Files 4 3 2 1 File Accesses That Do Not Sense Tags This section describes what happens when a program does not use a XABITM control block to sense a tag when it opens a file When a program opens a DDIF file for record operations and does not sense the tag RMS assumes that the program wants to access text in the file In this case RMS associates the RMS extension with the file access which provides file attributes that correspond to record mode access When a program opens a DDIF file with the FAB V BRO option and does not sense the tag any subsequent attempt to use block I O fails If the program specifies block I O FAB V BIO when it invokes the Connect service the operation fails because the file attributes returned at Open permit record access only Similarly if the program specifies the FAB V BRO option when it opens the file and then specifies mixed mode block record operations by not specifying RAB V BIO at connect time block operations such as READ and WRITE are disallowed 4 3 2 2 File Accesses That Sense Tags RMS does not associate the RMS extension with the file access as part of the Open service if a program opens a DDIF file and senses the stored semantics This allow
117. 0 OK ROAD 41 55 48 53 41 4E 20 44 0038 NASHUA 33 30 48 4E 20 20 20 20 0040 NH030 00 31 36 30 0048 62 ANALYZE gt NEXT DATA BYTES VBN 1 offset X 004C 7 65 4 3 2 1 0 01234567 32 30 30 30 30 30 00 49 0000 1 000002 49 46 46 4F 20 42 44 41 0008 ADB OFFI 4C 50 50 55 53 20 45 43 0010 CE SUPPL 20 20 20 20 20 53 45 49 0018 IES 32 34 20 20 20 20 20 20 0020 AF 4D 45 53 4F 52 20 30 0028 0 ROSEMO 45 52 54 53 20 54 4E 55 0030 UNT STRE 49 44 20 4E 41 53 54 45 0038 ETSAN DI 32 39 41 43 20 4F 47 45 0040 EGO CA92 00 303131 0048 110 continued on next page Maintaining Files 10 13 Maintaining Files 10 1 Viewing File Characteristics Example 10 3 Cont Examining a Sequential File ANALYZE gt NEXT DATA BYTES VBN 1 offset X 0098 ANALYZE EXIT 10 14 Maintaining Files 7 6 5 4 3 2 0000 0008 0010 0018 0020 0028 0030 0038 0040 0048 01234567 1 000003 COLOR PR INTING L ABORATOR IES 94 9 EAST 5 TH STREE T NEW YO RK NY10 003 Maintaining Files 10 1 Viewing File Characteristics 10 1 5 Examining a Relative File Figure 10 3 shows the tree structure of relative files Figure 10 3 Tree Structure of Relative Files File Header File Attributes First Data Second Last Data Bucket Data Bucket Bucket First Record Last Record First Record Cell in Cell in Cell in First Bucket First Bucket Second Bucket ZK 0328 GE The tree structure of rela
118. 0 eee eee eee 2 14 Sequential File Organization Advantages and Disadvantages 2 16 Relative File Organization Advantages and Disadvantages 2 18 Indexed File Organization Advantages and Disadvantages 2 25 Summary of the Edit FDL Utility Commands 4 3 Edit FDL Utility Scripts 0 2 nee 4 4 File Specification Defaults 20 0 0 ce ees 6 2 Example of Applying Defaults leen 6 3 File Access Record Operations 0 00 e eens 7 3 File Sharing Record Operations 0000 cece eee nee 7 4 Initial File Sharing and Subsequent File Access 7 6 Initial File Access and Subsequent File Sharing 7 6 Methods Available for Specifying No Query Record Locking 7 12 Compatibility of Record Locking Options 005 7 13 Record Operations and File Organizations 000 8 2 Search Key Types sesso res ker RERO IREE Rn ease a eee EERS 8 9 Record Access Stream Context 0 0 0 cee eee 8 15 ANALYZE RMS FILE Command Summary 00005 10 11 xi Preface Intended Audience This document is intended for applications programmers and designers who create or maintain application programs that use RMS files You may also read this document to gain a general understanding of the file and record processing options available on an OpenVMS system Document Structure This guide contains 10 chapters
119. 1 The index records in this example are 6 bytes long Each index record has one byte of control information In this example the size of the pointers is 2 bytes per index record for a total index record size of 9 bytes You calculate the number of records per bucket in this case as follows 512 15 55 2 9 Again you must round the remainder down to the next lower integer 55 Figure 3 2 Primary Index Structure 3 6 9 12 15 18 21 24 27 Level 1 Root Level Level 0 Data Level 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 ZK 0735 GE To read the record with the primary key 14 RMS begins by scanning the root level bucket looking for the first index record with a key value greater than or equal to 14 This record is the index record with key 15 The index record contains a pointer to the level 0 data bucket that contains the records with the keys 13 14 and 15 Scanning that bucket RMS finds the record see Figure 3 3 Performance Considerations 3 21 Performance Considerations 3 5 Tuning an Indexed File Figure 3 3 Finding the Record with Key 14 Z Find First Key Search for Key 14 Greater Than Begins or Equal to 14 3 6 9 12 15 18 21 24 27 8 Go to Bucket Find Record 16 17 18 19 20 21 25 26 27 ZK 0736 GE 3 5 1 3 Alternate Index Structure Alternate indexes also referred to as secondary
120. 134 59 0 BTEST2 DKA200 134 59 0 BTEST2 If a specification contains both a root with a DID and a directory with a DID the root will be ignored though not elided by RMS The directory ID numbers are those that are displayed for a directory with the DIRECTORY FILE_ID DCL command as shown in the following DIRECTORY FILE ID NOHEADER NOTRAILING WIDTH FILE 45 DIR l1 DKA200 SYSTEM 1 DIR 1 24 42 0 DKA200 SYSTEM a DIR 1 1223 4 0 DKA200 SYSTEM BTEST1 DIR 1 134 59 0 DKA200 SYSTEM DIR 1 DIR 1 609 22 0 DKA200 SYSTEM lowercase DIR 1 655 49 0 DKA200 SYSTEM te mp DIR 1 20 37 0 DKA200 SYSTEM tmp tmp DIR 1 355 20 0 DKA200 SYSTEM UNICODE DIR 1 1968 10 0 DKA200 SYSTEM UPPERCASE DIR 1 656 45 0 DKA200 SYSTEM with dot DIR l 768 28 0 When RMS attempts to generate a file specification that is too long for the application s output buffer pointed to by the NAM block expanded or resultant string field NAM L ESA or NAM L RSA or by the NAML block short expanded or short resultant string file NAML L ESA or NAML L_RSA it replaces the root and directory component with one that has the DID for the lowest level subdirectory of the replaced component s The specification that results can then be used as input to RMS It should be noted that not all RMS features are available with DIDs For example attempts to use sticky defaulting with a root or directory with a DID will result
121. 1Q01QG91Q1010101 A N 3 S aS os et 5 8 Introduction to File Parsing llle eene 5 21 5 9 Using One File Specification to Locate Many Files 5 22 5 9 1 Processing One File 1 0 0 eee 5 27 5 9 2 Processing Many Files 2 0 cece eens 5 28 5 9 3 Processing One or Many Files 0 00 nee 5 29 6 Advanced Use of File Specifications 6 1 How RMS Applies Defaults 0 0 0 6 1 6 2 Understanding RMS Parsing 0 cece eee eee 6 4 6 2 1 Checking for Open by Name Block 0 2 00 ce eee eee 6 5 6 2 2 File Specification Formats and Translating Logical Names 6 5 6 2 3 Special Parsing Conventions 0 00 ce eee eens 6 6 6 2 3 1 Parsing Conventions for a Search List 004 6 7 6 2 3 2 Special Processing for a Related File Specification 6 8 6 2 3 3 Input File Specification Parsing llle 6 9 6 2 3 4 Output File Specification Parsing llle 6 10 6 3 Directory Syntax Conventions and Directory Concatenation 6 11 6 3 1 Using Normal Directory Syntax 0 0 0 0 cece nee 6 11 6 3 2 Rooted Directory Syntax Applications 0 00 0 eens 6 14 6 3 3 Using Rooted Directory Syntax lees 6 14 6 3 4 Concatenating Rooted Directory Specifications 6 15 6 3 5 An Example of Using a Rooted Directory 0000005 6 17 6 3 6 Using a Rooted Directory to Exte
122. 2 3 Table 2 3 Sequential File Organization Advantages and Disadvantages Advantages Disadvantages Simplest organization To get a particular record most higher level languages must access all the records before it no random access by key Minimum overhead on disk Interactive processing is awkward operator must wait as the program searches for a record Allows block spanning You can add records only to the end of the file Optimal if application accesses all records on each run Most versatile format exchange data with systems other than RMS compatible with ANSI magnetic tape format No restrictions on the type of storage media the file is portable Random access by key available on fixed format disk sequential files l This restriction does not apply to disk sequential files with fixed length record format Records in such files can be stored and retrieved using random access by key depending on language capabilities 2 16 Choosing a File Organization Choosing a File Organization 2 2 File Organization Concepts 2 2 2 Relative File Organization The relative file organization allows sequential and random access of records on disk devices only Note Although relative files are not supported for magnetic tape operations magnetic tape can be used to transport relative files In fact relative files provide the fastest random access and they require fewer tuning considerations A relative
123. 2 3 3 Input File Specification Parsing When the output file parsing bit FAB V OFP is reset and the node name is omitted RMS processes the related file specification as an input file specification This is shown in the following table Note that the only wildcard character allowed is a single asterisk File Specification Null Field Wildcard Field Component Specification Specification Node Use related file Illegal specification Device Use related file Illegal pecification Directory Use related file Remains wild pecification Filename Use related file Remains wild pecification Type Use related file Remains wild specification Version Remains null Remains wild When the FAB V_OFP bit is reset and a node name is present RMS processes the related file specification as an input file specification as shown in the following table File Specification Null Field Wildcard Field Component Specification Specification Device Remains null Illegal Directory Remains null Remains wild Advanced Use of File Specifications 6 9 Advanced Use of File Specifications 6 2 Understanding RMS Parsing File Specification Null Field Wildcard Field Component Specification Specification Filename Use related file Remains wild specification Type Use related file Remains wild specification Version Remains null Remains wild 6 2 3 4 Output File Specification Parsing When the FAB V_OFP bit is set and a nod
124. 2 File Organization Concepts NCS F NOT CS name or id is not a CS Example 2 1 illustrates the use of collated keys in a MACRO 32 program segment Example 2 1 Creating a File Containing Collated Keys TITLE Example i Define key type as COL or DCOL Li KEY0 SXABKEY DTP COL Descriptor for collating sequence name CS DESC ASCID Spanish EXTRN NCS GET CS Collating sequence name descriptor PUSHAL CS DESC Where to store address of collating sequence PUSHAL KEY0 XAB L_COLTBL Fetch collating sequence CALLS 12 G NCSSGET CS BLBC RO ERROR Create file SCREATE FAB OUTFAB BLBC RO ERROR 2 2 3 6 Summary of Indexed File Organization Some advantages and disadvantages of the indexed file organization are outlined in Table 2 5 Table 2 5 Indexed File Organization Advantages and Disadvantages Advantages Disadvantages Most flexible random access by any one Highest overhead on disk and in memory of multiple keys or RFA key access by generic or approximate value continued on next page Choosing a File Organization 2 25 Choosing a File Organization 2 2 File Organization Concepts Table 2 5 Cont Indexed File Organization Advantages and Disadvantages Advantages Disadvantages Duplicate key values possible Restricted to disk Automatic sort of records by primary Most complex programming and alternate keys available during sequential access Record location is transparent to us
125. 2 Using RMS Statistics This section provides an example of how you can use RMS statistics to improve file processing performance In this example the system manager suspects that an I O bottleneck involving the file DATABASE DAT is causing a system performance problem To confirm the suspicion the system manager enables statistics monitoring on the file Note that if the system manager does not have sole access to the file the SET FILE command returns a file access conflict error message You can use the SHARE qualifier in conjunction with the STATISTICS qualifier to enable or disable statistics on a file that is currently being accessed However only statistics of new accessors of the file will be measured The system manager invokes the Monitor utility to obtain a periodic sampling of RMS statistics that describe the processing activity related to DATABASE DAT The statistics relating to the operations rate the buffer caching rate the data rate and the locking rate displayed on the Monitor screens provide the system manager with information for making decisions about where to place the file on disk and how to select optimal tuning parameters for the file Using the DCL interface the system manager enables statistics gathering with the following command SET FILE STATISTICS DATABASE DAT The SET FILE STATISTICS command applies an application access control entry ACE to the specified file The ACE does not affect access control and
126. 3 2 1 5 Waits OF VO i oy ate washed ee We a BAS ee we bce Be nea 1 35 1 36 1 36 1 37 1 37 1 37 1 38 1 39 1 39 1 40 1 40 1 41 mo m m m m PS DN PP l coc o0nm c 000i KK KRD 3 2 1 6 3 2 1 7 3 2 2 3 2 2 1 3 2 2 2 3 2 2 3 3 2 2 4 3 3 3 3 1 3 3 2 3 3 3 3 3 4 3 3 5 3 4 3 4 1 3 4 2 3 4 3 3 4 4 3 5 3 5 1 3 5 1 1 3 5 1 2 3 5 1 3 3 5 1 4 3 5 1 5 3 5 1 6 3 5 2 3 5 2 1 3 5 2 2 3 5 2 3 3 5 2 4 3 5 2 5 3 6 3 6 1 3 6 2 3 7 3 7 1 3 7 1 1 3 7 1 2 3 7 2 Multiple Areas for Indexed Files e oo ois he eee a ee Bucket Fill Factor for Indexed Files 000 Processing Options Multiple Buffers Deferred Write Processing Global Buffers Read Ahead and Write Behind Processing Tuning a Sequential File Block Span Option Multiblock Size Option Number of Buffers Global Buffer Option Read Ahead and Write Behind Tuning a Relative File Bucket Size Number of Buffers Global Buffer Option Deferred Write Option Tuning an Indexed File File Structure Prologs 5s re Primary Index Structure Alternate Index Structure Records Optimizing File Performance Bucket Size Fill Factor Number of Buffers Global Buffers Options 0 0 cee eee Using the De
127. 4 3 2 1 File Accesses That Do Not Sense Tags llle 4 3 2 2 File Accesses That Sense Tags llle 4 3 3 Preserving Tags i ka Reate 9 ORE OR TUER RE YER ERO 4 4 Defining File Protection llle 4 4 1 UIC Based Protection uso eR Ow ee OR pe eoe la 4 4 2 ACL Based Protection 0 0 0 cc eee eee eee eens 4 5 Populating File sca06 acedede abel stage uhoa dodge SP UR RUN ee awed 4 5 1 Using the Convert Utility 0 0 0 0 0c eee 4 5 2 Using the Convert Routines 0 0 00 4 6 Summary of File Creation Options 0 0000 cece eee ee 4 6 1 File Creation Options 0 0 cc eee eee 4 6 2 File Characteristics 0 eee eee eee 4 6 3 File Allocation and Positioning llle 5 Locating and Naming Files on Disks vi 5 1 Understanding Disk File Specifications 0000s 5 2 File Specification Components 0 00 eee eA 5 2 1 The Node Component llle 5 2 1 1 Local Node ii iesus keen ve dea bidak Eque e hie cade 5 2 1 2 Remote Node 4 slew e ku ERES ERE LER ERES 5 2 2 The Device Component llle 5 2 3 On Disk Components llle 5 2 3 1 Character Set for On Disk Components 005 5 2 3 1 1 Base Character Set 0 0 0 cece eee eee ee 5 2 3 1 2 Extended Character Set 0 0 0 0 cece eee eee 5 2 4 RMS and On Disk Representation 0 000 e eee ee eee 5 2 4 1 Simple Characters 0
128. 4 32 key definition fields 4 33 protection fields 4 33 Y Year 2000 readiness magnetic tape dating 1 30 Z Zero creation date 1 31 Index 15
129. 6 4 File specifications cont d related 6 1 to 6 4 6 8 6 9 9 7 using logical name 6 5 6 6 using name block 5 21 using search lists 5 21 to 5 29 6 7 6 8 using SYS DISK 6 2 using wildcard characters 5 21 to 5 29 File specifications parsing 5 21 5 22 File structures 10 11 options on OpenVMS systems 1 3 File tags creating 4 20 requirement for 4 19 using 4 19 File tuning See Tuning File type field 1 28 File types 5 9 File versions 5 9 FILE ID option 4 36 FILE MONITORING attribute 3 29 FILE NAME option 4 36 Fill factor 3 26 Find service compared with Get service 8 2 effect on next record position 8 17 high level language equivalents 8 1 improved performance 8 3 key matches and 8 11 requirement for end of file test 8 3 run time options 9 14 to 9 18 FIRST command 10 11 Fixed length cells 3 15 Fixed length control fields 3 15 size option 4 33 Fixed length records 1 31 Flush service 7 6 8 5 FORMAT attribute 4 34 Formats for ANSI magnetic tape volumes 1 20 Fortran program example calling the FDL CREATE Routine 4 17 remote file access 5 18 using the CONVERT Routines 4 27 Fragmented files 3 4 to 3 9 Free service 8 5 G GBLPAGES system parameter 1 40 GBLPAGFIL system parameter 1 40 GBLSECTIONS system parameter 1 40 Generation version number 1 30 Generic key match 8 12 GET attribute 7 4 7 24 Get service
130. 67 version limits are not supported e Enhanced protection features for example access control lists not supported e Extended File Specifications Not supported e RMS journaling for OpenVMS Not supported Introduction 1 11 Introduction 1 2 Disk Concepts e RMS execution statistics monitoring Not supported 1 2 4 Physical Structures For performance reasons you should be aware of certain physical aspects of a disk A disk or volume consists of one or more platters that spin at very high constant speeds and usually contain data on both surfaces upper and lower A disk pack is made up of two or more platters having a common center Data is located at different distances from the center of the platter and is stored or retrieved using read write heads that move to access data at various radii from the platter s center The time required to position the read write heads over the selected radius referred to as a track is called seek time Each track is divided into 512 byte structures called sectors The time required to bring the selected sector logical block under the read write heads at the selected radius track is called the rotational latency Because seek time usually exceeds the rotational latency by a factor of 2 to 4 related blocks sectors should be located at or near the same track to obtain the best performance when transferring data between the disk and RMS maintained buffers in memory Typically
131. 7 15 7 2 3 3 Reading Regardless of Lock 0 00 cece eee eens 7 15 7 2 4 Miscellaneous Record Locking Options llle 7 15 7 2 4 1 Manual Unlocking Option 0 000 cee eee eee 7 15 7 2 4 2 Lock Nonexistent Record Option 0 0000 e cece eeee 7 16 7 2 5 Record Locking Deadlocks 20 0 0 eee ees 7 16 7 2 5 1 Record Locking Options to Control Deadlock Detection 7 17 vii 7 3 7 3 1 7 3 2 7 3 3 7 3 4 7 3 5 7 3 6 7 3 6 1 Local and Shared Buffering Techniques 0000 ee eue Record Transfer Modes Understanding Buffering Buffering for Sequential Files llle Buffering for Relative Files 20 0 eee eee ee ee Buffering for Indexed Files 20 0 0 ee eee Using Global Buffers for Shared Files 0000000 Enhancing Global Buffer Performance 8 Record Processing 8 1 8 2 8 2 1 8 2 2 8 2 3 8 2 4 8 3 8 4 8 4 1 8 4 1 1 8 4 1 2 8 4 2 8 4 2 1 8 4 2 2 8 4 3 8 4 3 1 8 4 3 2 8 4 4 8 5 8 6 8 6 1 8 6 2 8 7 8 7 1 8 7 2 Record Operations Primary Services Locating and Retrieving Records 0 000 e eee teens Inserting Records Updating Records Deleting Records Secondary Services Record Access for the Various File Organizations Processing Sequential Files llli Sequential Access Random Ac
132. 7 54 24 Contiguity Options contiguous best try Performance Options none Reliability Options none Journaling Enabled none RMS FILE ATTRIBUTES File Organization indexed Record Format variable Record Attributes carriage return Maximum Record Size 80 Blocks Allocated 30 Default Extend Size 2 Bucket Size 1 File Monitoring disabled Global Buffer Count 0 FIXED PROLOG Number of Areas 8 VBN of First Descriptor 3 Prolog Version 3 AREA DESCRIPTOR 0 VBN 3 offset X 0000 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 1 Blocks 9 Used 4 Next 5 Default Extend Quantity 2 Total Allocation 9 STATISTICS FOR AREA 0 Count of Reclaimed Blocks 0 AREA DESCRIPTOR 1 VBN 3 offset X 0040 continued on next page 10 6 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics Example 10 2 Cont Using ANALYZE RMS FILE to Create a Statistics Report Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 10 Blocks 3 Used 1 Next 11 Default Extend Quantity 1 Total Allocation 3 STATISTICS FOR AREA 1 Count of Reclaimed Blocks 0 AREA DESCRIPTOR 2 VBN 3 offset X 0080 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 13 Blocks 3 Used 1 Next 14 Default Extend Quantity 1 Total Allocation 3 STATISTICS FOR AREA 2 Count of Reclaimed Blocks 0 AREA DESCRIPTOR 3 VBN 3 offset X 00C0 Bucket Size 1 Reclaimed Buc
133. A ANL CUSTDATA DAT To place the Check report in a file use a command of the form ANALYZE RMS_FILE CHECK OUTPUT output filespec input filespec The Check report will be placed in the file you named with the output filespec parameter This file will receive the file type ANL by default For example the following command will perform an error check on PRLG2 IDX and place the Check report in the file ERROR ANL ANALYZE RMS FILE CHECK OUTPUT ERROR PRLG2 IDX Maintaining Files 10 5 Maintaining Files 10 1 Viewing File Characteristics 10 1 2 Generating a Statistics Report For indexed files the Statistics report consists of the Check report plus additional information about the areas and keys in the file A Statistics report on a sequential or relative file is thus the same as a Check report To generate a Statistics report with ANALYZE RMS FILE enter a DCL command of the form ANALYZE RMS FILE STATISTICS filespec Example 10 2 is an example of a Statistics report Example 10 2 Using ANALYZE RMS FILE to Create a Statistics Report RMS File Statistics 18 APR 1993 11 22 27 14 Page 1 DISK TEST PROGRAM INDEX DAT 1 FILE HEADER File Spec DISK TEST PROGRAM INDEX DAT 1 File ID 15960 8 0 Owner UIC 011 310 Protection System RWED Owner RWED Group RWED World RWE Creation Date 19 APR 1993 22 15 55 70 Revision Date 19 APR 1993 22 16 01 74 Number 4 Expiration Date none specified Backup Date 18 APR 1993 00 5
134. ALL can be used to place an extend on a particular disk block or disk cylinder If no allocation XAB is present on the EXTEND and the FAB contiguity options described later in this section are not selected RMS automatically places the extend near the last allocated disk block in the file If the file being extended in this fashion is an indexed file opened for record I O access RMS adds the new disk space as near as possible to the last allocated disk block in the area being extended This technique groups disk blocks belonging to the same area of the indexed file When RMS automatically extends a file the application cannot control placement however RMS uses placement controls in one of the following ways depending on how the file is organized e When automatically extending an indexed file RMS uses placement control to allocate the new disk space as close as possible to the last allocated disk block of the indexed file area being extended e When automatically extending a relative file RMS uses placement control to allocate the new disk space as close as possible to the last allocated disk block of the file e No placement control is used when RMS automatically extends a sequential file or any file organization accessed for block I O An extend is considered contiguous if all the disk blocks of the extend are physically adjacent on the disk There are two types of contiguous extend requests that can be made The first called a con
135. B IF NOT STATUS THEN SIGNAL STATUS STATUS CLOSE FAB FAB IF NOT STATUS THEN SIGNAL STATUS XAB ACCESS SEMANTICS continued on next page 4 24 Creating and Populating Files Creating and Populating Files 4 3 Creating and Accessing Tagged Files Example 4 7 Cont Accessing a Tagged File END END ELUDOM 4 3 3 Preserving Tags In order to preserve the integrity of a tagged file that is being copied or transmitted the tag must be preserved in the destination output file The most efficient way to use the RMS interface for propagating tags involves a 2 step procedure 1 Open the source file input and sense the tag using a XABITM macro with the item code XAB STORED SEMANTICS as shown in the following example ITEMLIST ITM W BUFSIZ ITEMLIST ITM L BUFADR ITEMLIST ITM L RETLEN ITEMLIST ITM W ITMCOD XABSK SEMANTICS MAX LEN ITEM BUFF RETLEN XAB STORED SEMANTICS XABITM XAB B MODE XAB K SENSEMODE STATUS OPEN FAB FAB Create the destination output file and set the tag using a XABITM macro with the item code XAB STORED SEMANTICS IF RETLEN GTR 0 THEN BEGIN ITEMLIST ITM W ITMCOD XAB STORED SEMANTICS ITEMLIST ITMSL SIZE RETLEN XABITM XAB B MODE XAB K SETMODE END STATUS SCREATE FAB FAB END END ELUDOM 4 4 Defining File Protection You can protect a disk file in two ways UIC based protection codes A
136. BUTES qualifier 5 20 Asynchronous operations 8 18 8 19 performance 9 8 Attributes creation by the Edit FDL utility 4 3 primary 4 9 Auto extends for Block I O with sequential files 3 5 for indexed files 3 6 how to establish default quantity 3 6 maximized value 3 5 minimal size 3 5 size selection 3 5 specifying size 3 5 Auto extend size selections 3 5 Backup log file 1 10 Backup operations 1 34 Backup utility BACKUP 10 2 eliminating extents 9 8 making archive copies 10 29 BADBLK SYS file 1 10 Bad block file 1 10 BADLOG SYS file 1 10 Index 1 Base character set 5 4 BASIC USEROPEN routine 5 23 9 5 Beginning of tape marker See BOT markers BEST TRY CONTIGUOUS attribute 3 24 4 35 Binary data 1 20 BITMAPSYS file 1 9 Bitmaps index file 1 9 storage 1 9 Bits per inch bits inch 1 18 Blocked record 1 31 Block I O 8 15 Block length field 1 32 Blocks 1 7 3 10 Block size options 4 32 Block span options 3 13 effect on maximum record size 2 9 FDL RECORD section 4 33 BLOCK IO attribute 7 3 BLOCK SPAN attribute 3 13 4 34 Bootstrap block 1 8 BOT markers 1 22 Buckets 3 10 3 20 boundary 3 22 definition 2 1 reclaiming 3 20 10 28 Bucket size options 4 32 A 1 considering performance 3 26 for indexed files 7 21 for relative files 7 20 relative to index depth 3 25 with multiple areas 3 24 Bucket splits 3 10 3 23 9 13 cleaning
137. CK Specifies that transfers to volumes are to be checked by a read compare operation which effectively doubles the amount of disk I O performed This option is not available for all devices see the OpenVMS Record Management Services Reference Manual e FDL FILE WRITE_CHECK e RMS FAB L_FOP FAB V_WCK 9 2 7 Options for File Disposition The run time file open options that apply to file disposition are listed in the following table These options can only be selected while the file is open Run Time Options 9 11 Run Time Options 9 2 Options Related to Opening and Closing Files Option Description Delete on close Submit command file Spool on close Deletes the file when it is closed e FDL CONNECT DELETE ON CLOSE e RMS FAB L FOP FAB V_DLT Submits a sequential file as a batch command procedure to SYS BATCH when you close the file e FDL FILE SUBMIT_ON_CLOSE e RMS FAB L_FOP FAB V_SCF Prints a sequential file on SYS PRINT when you close the file e FDL FILE PRINT_ON_CLOSE e RMS FAB L_FOP FAB V_SPL 9 2 8 Options for Indexed Files The following table lists the run time options that apply to indexed file processing For more information about processing indexed files refer to Section 8 4 3 Option Description Fast delete Key equal or next Next key Postpones certain internal operations associated with deleting indexed file records until the record is accessed again Th
138. CORD CARRIAGE CONTROL FORMAT SIZE CONNECT WRITE BEHIND AREA 0 ALLOCATION BEST TRY CONTIGUOUS BUCKET SIZE EXTENSION AREA 1 ALLOCATION BEST TRY CONTIGUOUS BUCKET SIZE EXTENSION 9 4 Run Time Options OpenVMS FDL Editor VMS indexed carriage return variable 0 yes 8283 yes 2070 18 yes 18 Run Time Options 9 1 Specifying Run Time Options KEY 0 CHANGES no DATA AREA 0 DATA FILL 100 DATA KEY COMPRESSION yes DATA RECORD COMPRESSION yes DUPLICATES no INDEX AREA 1 INDEX COMPRESSION yes INDEX FILL 100 LEVEL INDEX AREA 1 PROLOG 3 SEGO LENGTH 9 SEGO POSITION 0 TYPE string 9 1 2 Using Language Statements and RMS Language statements such as OPEN may contain keywords clauses or other modifiers that correspond to the run time attributes that are appropriate for opening files connecting record streams processing records and closing files Some languages use system defined procedures in place of keywords and clauses Some languages allow you to call a user supplied routine USEROPEN or USERACTION to set control block values before opening the file For example a user routine could be coded in VAX MACRO to take advantage of control block store macros For an example of a VAX BASIC USEROPEN routine see Example 5 2 Consult the corresponding language documentation for additional information With VAX MACRO RMS control block macros allow you to establish control block values at assemb
139. Cee Ne O00 O0ONNNODOO AH ibi P Pp LALL 9 2 9 9 2 10 9 3 9 3 1 9 3 2 9 3 3 9 3 4 9 4 Options for Magnetic Tape Processing llle Options for Nonstandard File Processing 00000 0 Summary of Record Operation Options 0 0 0 Record Retrieval Options llle Put Service Options 2s ux rex ORT nea RR SR a SCR EONTR Rn Record Update Options llle Record Deletion Options 0 00 ees Run Time Example i 22 29 44 ences ERR ERGOS ER UE ERR wud 10 Maintaining Files 10 1 10 1 1 10 1 2 10 1 3 10 1 4 10 1 5 10 1 6 10 2 10 8 10 3 1 10 3 2 10 4 10 4 1 10 4 2 10 4 3 10 5 10 6 Viewing File Characteristics llle Performing an Error Check l l Generating a Statistics Report llle Using Interactive Mode 0 0 es Examining a Sequential File 0 0 20 eee eee Examining a Relative File 0 0 0 cc eee Examining an Indexed File 2 0 0 c eee eee Generating an FDL File from a Data File 0 04 Optimizing and Redesigning File Characteristics sn Redesigning an FDL File 20 0 cee es Optimizing a Data File 0 nee Making a File Contiguous llle Using the Copy Utility 0 eee Using the Convert Utility 2 0 0 0 0 0c eee Reclaiming Buckets in Prolog 3 Files 00002 ee Reorganizing File creek en
140. D e RMS RAB L_ROP RAB V_REA Locks record for writing and allows other readers but no writers e FDL CONNECT LOCK_ON_WRITE e RMS RAB L_ROP RAB V_RLK Allows you to control record locking and unlocking manually e FDL CONNECT MANUAL LOCKING e RMS RAB L_ROP RAB V ULK Improves performance at the expense of additional memory for I O buffers For sequential access to sequential files only e FDL CONNECT READ_AHEAD e RMS RAB L_ ROP RAB V_RAH Run Time Options 9 3 Summary of Record Operation Options Option Description Read regardless Record access RFA Record header buffer Timeout period User buffer address Reads the specified record regardless of whether it is locked by another user e FDL CONNECT READ REGARDLESS e RMS RAB L ROP RAB V RRL Specifies the way records are accessed sequentially randomly by key indexed files by record number relative files or randomly by RFA e FDL None e RMS RAB B_RAC values RAB C_SEQ RAB C_KEY RAB C_RFA Specifies the address of the desired record when records are accessed randomly by RFA RAB B_RAC contains RAB C_RFA This value is also returned by Find and Get services regardless of the type record access used e FDL None e RMS RABS W RFA Contains the symbolic address of the record header buffer that contains the fixed portion of a VFC record Applies to the Get service only e FDL None e RMS RAB L_RHB Specifies a timeout period
141. DLSCREATE statistics DATA NAMES OUT REC defines the output record STATVALUE receives the status value from the routine call NORMAL receives the value from SS NORMAL FIDBLOCK receives the FDLSCREATE statistics There are three 1 file identification number FID NUM 2 file sequence number FID SEQ 3 relative volume number RVN Bb B b ob ox o ox ox ox ow ok ob ot ob ob ob ob ob ok ok ot o RESNAME receives the name of the file that is created the result file name IDENTIFICATION DIVISION PROGRAM ID FDL CREATE EXAMPLE ENVIRONMENT DIVISION CONFIGURATION SECTION SOURCE COMPUTER VAX OBJECT COMPUTER VAX INPUT OUTPUT SECTION FILE CONTROL SELECT OUT FILE ASSIGN TO NEWMASTER DAT DATA DIVISION FILE SECTION FD OUT FILE DATA RECORD IS OUT REC 01 OUT REC 02 OUT NUM PIC X 4 02 OUT NAME PIC X 20 02 OUT COLOR PIC X 4 02 OUT WEIGHT PIC X 4 02 SUPL NAME PIC X 20 02 FILLER PIC X 28 WORKING STORAGE SECTION 01 MORE DATA FLAGS PIC XXX VALUE YES 88 THERE IS DATA VALUE YES 88 THERE IS NO DATA VALUE NO 01 STATVALUE PIC S9 9 COMP 01 FIDBLOCK USAGE IS COMP 02 NUM PIC S9 9 VALUE 0 02 SEQ PIC S9 9 VALUE 0 02 RVN PIC S9 9 VALUE 0 01 RESNAME PIC X 50 continued on next page 4 18 Creating and Populating Files Creating and Populating Files 4 2 Creating a File Example 4 5 Cont Using the FDL CREATE Routine from a COBOL Program PROCEDURE DIVISION MAIN PERFORM C
142. Data Fill Quantity 512 Segment Positions Segment Sizes 5 Data Type string Name ID NAME First Data Bucket VBN 13 STATISTICS FOR KEY 1 Number of Index Levels Count of Level 1 Records Mean Length of Index Entry Count of Index Blocks Mean Index Bucket Fill Mean Index Entry Compression oo oo Count of Data Records Mean Duplicates per Data Record Mean Length of Data Record 19 Count of Data Blocks 1 Mean Data Bucket Fill 248 Mean Data Key Compression 0 KEY DESCRIPTOR 2 VBN 2 offset X 0066 Next Key Descriptor VBN 2 Offset X 00CC Index Area 5 Level 1 Index Area 5 Data Area 4 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 22 Key Flags 0 KEYSV DUPKEYS 1 KEY V CHGKEYS 2 KEYSV NULKEYS 3 KEY V IDX COMPR 4 KEY V INITIDX 6 KEYSV KEY COMPR Key Segments 1 Key Size 10 Minimum Record Size 19 Index Fill Quantity 512 Data Fill Quantity 512 Segment Positions 9 Segment Sizes 10 Data Type string Name ADDRESS First Data Bucket VBN 19 DD CO pmb Im mr Oorr continued on next page Maintaining Files 10 9 Maintaining Files 10 1 Viewing File Characteristics Example 10 2 Cont Using ANALYZE RMS FILE to Create a Statistics Report STATISTICS FOR KEY 2 Number of Index Levels Count of Level 1 Records Mean Length of Index Entry Count of Index Blocks Mean Index Bucket Fill Mean Index Entry Compression mmn c o
143. ERROR BRB GET REC Skip error handling continued on next page Run Time Options 9 4 Run Time Example Example 9 2 Cont Using the FDL PARSE and FDL RELEASE Routines F ERROR R ERROR GET REC CLEAN FAB ERROR ERROR RAB ERROR RMS ERR FINI BRW FAB ERROR BRW RAB ERROR GET RAB R9 CMPL RMSS EOF RO BEQLU CLEAN BLBC RO R ERROR Li T Li T Get a record If not end of file continue MOVZWL RAB W RSZ R9 REC RESULT Move a record into PUSHAL REC RESULT CALLS 1 G LIBSPUT OUTPUT BLBC RO ERROR BRB GET REC CLOSE FAB R10 BLBC RO FAB ERROR PUSHAL MY RAB PUSHAL MY FAB CALLS 2 G FDLSRELEASE BLBC RO ERROR BRB FINI PUSHL FABS L_STV R10 PUSHL FAB L STS R10 BRB RMS ERR PUSHL R0 CALLS 1 G LIBSSIGNAL CLOSE FAB R10 BRW FINI PUSHL RAB L STV R9 PUSHL RABSL_STS R9 CALLS 2 G LIBSSIGNAL RET END FDLEXAM T the buffer Display the record Get another record Close the FAB Push RAB address on stack Push FAB address on stack Release the control blocks Successful completion Signal file error Signal error End program Signal record error Run Time Options 9 23 10 Maintaining Files Designing and creating your files and defining their records are only the first steps in the life cycle of your file You must also consider maintaining the file This chapter describes file maintenance with the emphasis on file tuning
144. F option 8 16 FAB V OFP option 6 8 6 9 6 10 FAB V PPF option 6 2 FAB V RCK option 9 11 FAB V SQO option 9 10 FAB V TMP option 4 32 FAB V UFO option 7 4 9 14 FAB V WCK option 9 11 FAB L_MRN field 4 33 FAB L MRS field 4 33 FAB L NAM field 6 8 9 7 FAB L NAML field 6 8 FAB L STV field 9 14 FAB V CTG option problem with fragmented disk 3 9 FAB W DEQ field 4 36 9 7 9 8 FAB W GBC field 7 19 7 23 9 9 FABDEF macro 5 23 FABs file access blocks 1 32 1 36 4 1 Fast delete option 8 4 9 8 FDL File Definition Language 1 35 3 16 4 2 attributes 4 2 predefined attributes using FDL PARSE routine 9 1 scripts 4 2 syntax 4 2 FDL AREA section 3 24 BEST TRY CONTIGUOUS attribute 4 35 EXACT POSITIONING attribute 4 36 POSITION attribute 4 35 VOLUME attribute 4 36 FDL CONNECT section ASYNCHRONOUS attribute 9 8 9 15 9 18 9 20 9 21 DELETE ON CLOSE attribute 9 12 END OF FILE attribute 9 10 FAST DELETE attribute 9 8 9 12 9 21 FILL BUCKETS attribute 9 13 9 18 GLOBAL BUFFER COUNT attribute 9 9 KEY GREATER EQUAL attribute 8 8 8 9 9 12 9 15 KEY GREATER THAN attribute 8 8 8 9 9 12 9 15 KEY LIMIT attribute 9 13 9 16 KEY OF REFERENCE attribute 9 13 9 15 LOCATE MODE attribute 9 9 9 16 LOCK ON READ attribute 7 13 9 16 LOCK ON WRITE attribute 7 13 9 16 9 19 MANUAL LOCKING attribute 9 16 MANUAL UNLOCKING a
145. FAB L_FOP field for the Close service the asynchronous RAB V_ ASY bit of the RAB L_ROP field the multiblock count field RAB B_MBC and the multibuffer count field RAB B_MBF or optionally the XAB _ MULTIBUFFER COUNT XABITM If a name block is used and either an expanded or resultant file specification string is returned the string consists solely of the process logical name followed by a colon such as SYS INPUT The file access FAB B FAC field is ignored by the Open service instead operations are checked against the FAB B FAC field specified for the original Open or Create service Information from the record attributes field is saved on each Open service and subsequent Connect service in the values returned in the internal file identifier and internal stream identifier fields If the output file is a print file VFC record format and the FAB V_PRN bit set in the record attributes field mapping is performed for each Put service from the user specified carriage control to the print file carriage control format Thus different carriage control types from different indirect Open services all work correctly You cannot use the Erase service Checking is performed for DECK EOD and other dollar sign records on the SYS INPUT stream if the SYS INPUT stream is from a file Checking is not done if SYS INPUT comes from a record oriented device such as a terminal or a mailbox See the OpenVMS DCL Dictionary At image exit
146. FDL files created by ANALYZE RMS FILE contain statistics about each area and key in the primary sections named ANALYSIS OF AREA and ANALYSIS OF KEY These analysis sections are then used by the Edit FDL utility in its Optimize script You can compare the statistics in these sections with your assumptions about the file s use you may find some places in the file s structure where additional tuning will be possible To generate an FDL file from a data file use the following command syntax ANALYZE RMS FILE FDL filespec With a command of this type the FDL file obtains its file name from the input file specification to assign a different file name use the OUTPUT qualifier For example the following command would generate an FDL file named INDEXDEF FDL from the data file CUSTFILE DAT ANALYZE RMS FILE FDL OUTPUT INDEXDEF CUSTFILE DAT Example 10 8 shows an FDL file showing the KEY and ANALYSIS OF KEY sections for an indexed file with two keys 10 22 Maintaining Files Maintaining Files 10 2 Generating an FDL File from a Data File Example 10 8 KEY and ANALYSIS OF KEY Sections in an FDL File IDENT SYSTEM FILE RECORD AREA 0 KEY 0 KEY 1 2 JUN 1993 16 15 35 SOURCE ALLOCATION BEST TRY CONTIGUOUS BUCKET SIZE CONTIGUOUS EXTENSION GLOBAL BUFFER COUNT NAME H ORGANIZATION OWNER PROTECTION READ CHECK WRITE CHECK BLOCK SPAN CARRIAGE CONTROL FORMAT SIZE BEST TRY CONTIGUOUS BUCKET SIZE CO
147. Files With sequential files the number of local buffers and the size of the local buffers can be specified at run time You specify the number of local buffers with the FDL attribute CONNECT MULTIBUFFER COUNT and you specify the buffer size with the FDL attribute CONNECT MULTIBLOCK COUNT Sequential files provide an option that uses two buffers One buffer holds records to be read from the disk or written to the disk The other buffer awaits I O completion This is called read ahead and write behind processing and should be considered for sequential access to sequential files The number of buffers CONNECT MULTIBUFFER COUNT should be specified as 2 The length of the buffers used for sequential files is determined by the specified multiblock count CONNECT MULTIBLOCK COUNT For sequential access to a sequential file the optimum number of blocks per buffer depends on the record size but a value such as 16 is usually appropriate To see the default buffer count for the current process use the DCL command SHOW RMS DEFAULT To set the default buffer count for the current process use the DCL command SET RMS DEFAULT SEQUENTIAL BUFFER COUNT n where n is the number of buffers 7 3 4 Buffering for Relative Files With relative files buckets not blocks are the unit of transfer between the disk and memory The bucket size is specified when the file is created although the bucket size of an existing file can be changed by converting the file
148. Guide to OpenVMS File Applications Order Number AA PV6PE TK June 2002 This document is intended for application programmers and designers who write programs that use OpenVMS RMS files Revision Update Information This manual supersedes the Guide to OpenVMS File Applications OpenVMS Alpha Version 7 3 and OpenVMS VAX Version 7 3 Software Version OpenVMS Alpha Version 7 3 1 OpenVMS VAX Version 7 3 Compaq Computer Corporation Houston Texas 2002 Compaq Information Technologies Group L P Compaq the Compaq logo Alpha OpenVMS Tru64 VAX and VMS are trademarks of Compaq Information Technologies Group L P in the U S and or other countries Microsoft Windows and Windows NT are trademarks of Microsoft Corporation in the U S and or other countries Motif OSF 1 UNIX and X Open are trademarks of The Open Group in the U S and or other countries All other product names mentioned herein may be trademarks of their respective companies Confidential computer software Valid license from Compaq required for possession use or copying Consistent with FAR 12 211 and 12 212 Commercial Computer Software Computer Software Documentation and Technical Data for Commercial Items are licensed to the U S Government under vendor s standard commercial license Compaq shall not be liable for technical or editorial errors or omissions contained herein The information in this document is provided as is without warranty of
149. I a characters however OpenVMS systems ignore these characters on input 1 22 Introduction Introduction 1 3 Magnetic Tape Concepts Table 1 6 Labels and Components Supported by OpenVMS Systems Symbol Meaning BOT Beginning of tape marker EOF1 First end of file label EOF2 Second end of file label EOF3 Third end of file label EOF4 Fourth end of file label EOT End of tape marker label EOVI First end of volume label EOV2 Second end of volume label EOV3 Third end of volume label EOV4 Fourth end of volume label HDR1 First header label HDR2 Second header label HDR3 Third header label HDR4 Fourth header label VOLI First volume label VOL2 Second volume label TM Tape mark TM TM Double tape mark indicates an empty file section or the logical end of volume 1 3 1 4 Volume and File Configurations ANSI magnetic tape volumes support four file and volume configurations A single file residing on a single volume A single file requiring multiple volumes Multiple files residing on a single volume Multiple files requiring multiple volumes All these configurations conform to the following guidelines The file sequence number field allows as many as 9999 file sections for one file In effect the file length is unlimited Only one file section of a given file is written on a volume When multiple sections exist for one file each file section is written to a separate volume in the volume set The file section number
150. II text from a DDIF file The conditions that determine when this extension is called are described in this section A DDIF file is a sequentially organized file with 512 byte fixed length records If the DDIF to ASCII RMS extension is used to extract text from a DDIF file the accessed file appears as a sequentially organized file having variable length records with a maximum record size of 2048 bytes and an implicit carriage return One consideration in determining whether an access requires the RMS extension is the type of access FAB B FAC When an application program opens a file through the RMS program interface it must specify if it will be doing record I O default block I O BIO or mixed I O BRO operations where the program has the option of using either block I O or record I O for each access For example if block I O operations are specified RMS does not associate the RMS extension with the file access Another consideration is whether the program senses the tag when it opens a file If the program does not sense the tag when it opens a DDIF file for record access RMS associates the RMS extension with the file access during the Open service and returns the file attributes that have been modified by the extension The final consideration is the access semantics that the program specifies and the file s stored semantics tag If the program specifies block I O FAB V BIO operations RMS does not associate the RMS extension
151. K and RAB V RRL options in applications RMS precedence for the no query record locking option is as follows e The RAB V NQL option set in the RAB W ROP 2 field e At file open and applied if RAB V_NLK and RAB V RRL are set for the read operation The FAB V NQL option set in the FAB B_SHR field The SET RMS DEFAULT QUERY LOCKING DISABLE setting at the process level The SET RMS DEFAULT QUERY LOCKING DISABLE setting at the system level If the process QUERY LOCKING setting equals SYSTEM DEFAULT the default when the process is created RMS uses the system specified value 7 2 2 6 Put Service Considerations Because the Put service adds a new record the application program does not have to access an existing record However because adding a record is a multistep process the record that is being added must be locked until the entire process is finished The scenario for adding a record to a file begins with the application program moving a record into its buffer Next the application program calls the Put service which locks the record while it moves it from the application program buffer to the file When the record is in the file the Put service unlocks the record making it available to other record streams The locking process is transparent at the program level unless the application program selects the manual unlocking option If a record stream tries to add a record using the no locking option the Put s
152. L or LIB STOP routines The VAX MACRO program shown in Example 5 3 invokes the Parse service determines whether a wildcard character or search list is present and conditionally branches to a sequence of instructions that invoke the Search service followed by the Open service The resultant string is displayed after the file is opened For more information about the LIB routines see the OpenVMS RTL Library LIB Manual The next example program uses the PARSE and SEARCH functions demonstrates the use of C language s fopen function and shows how you can mix RMS calls and C I O calls Locating and Naming Files on Disks 5 25 Locating and Naming Files on Disks 5 9 Using One File Specification to Locate Many Files Example 5 3 uses cc rms fab and cc rms_nam to define the FAB and NAM control blocks and specify the arguments for the Parse and Search services The program shows how to preprocess a file specification using the Parse and Search services First the program prompts the user for an input file specification that may contain wildcard characters The program then searches each file that matches the file specification for the specified text string Finally the program outputs all records from the target files that contain the specified string Example 5 3 Using the Parse and Search Services Using Parse and Search Services include lt stdio h gt include lt ssdef h gt include lt stsdef h gt include l
153. LBUFQUO e Global sections GBLSECTIONS e Global pages GBLPAGES e Global page file pages GBLPAGFIL When DCL opens a process permanent file RMS places internal structures for the file in a special portion of P1 space called the process I O segment The segment size is determined by the system parameter PIOPAGES and cannot be expanded dynamically If there is insufficient space in the process I O segment for the internal structures DCL generates an error message and does not open the file 1 40 Introduction Introduction 1 8 Process and System Resources for File Applications For a complete description of these parameters see the OpenVMS System Manager s Manual 1 8 2 Process Limits If you anticipate asynchronous record I O or are going to access a shared file you should consider the following process limits Asynchronous system trap limit ASTLM Buffered I O limit BIOLM Direct I O limit DIOLM Enqueue quota limit ENQLM Open file limit FILLM For a complete description of these process limits see the OpenVMS System Manager s Manual Introduction 1 41 2 Choosing a File Organization When you write an application program you want the program to input data process it store it update it if necessary and output it at the right time in the right format Moreover the program should perform these functions quickly and accurately To achieve this objective you should consider the structure of your data
154. LE TEST nam NAM mrs 512 rfm FIX fac lt GET PUT UPD gt xab FAB XABITM REC BLOCK 512 BYTE STATUS RAB SRAB xab RAB XABITM fab FAB rsz 512 rbf REC usz 512 ubf REC DESC BLOCK 8 BYTE INITIAL 0 ROUTINE MAIN NOVALUE BEGIN STATUS CREATE FAB FAB IF NOT STATUS THEN SIGNAL STATUS STATUS CONNECT RAB RAB continued on next page Creating and Populating Files 4 21 Creating and Populating Files 4 3 Creating and Accessing Tagged Files Example 4 6 Cont Tagging a File IF NOT STATUS THEN SIGNAL STATUS STATUS CLOSE FAB FAB IF NOT STATUS THEN SIGNAL STATUS 4 3 2 Accessing a Tagged File This section details how RMS handles access to tagged files at the program level When a program accesses a tagged file RMS must determine whether and when to associate an RMS extension with the access This is important to the programmer because an RMS extension can change the attributes of the accessed file RMS extensions are system images that perform specialized file or record operations within the context of RMS Record management services can invoke an extension if specified conditions are met Functions provided by an extension are only accessible through the record managment services and are generally transparent to the application An example of an RMS extension is the DDIF to ASCII text translator RMS can call this extension to extract ASC
155. LEN 2 G STRSGET1 DX RO ERR ARGS G LIBSFIND FILE RO ERR E OPEN STV L R 2 G LIBSSIGNAL TERR 5 24 Locating and Naming Files on Disks 1 Se Me Me se se Me Mo se se ne xe se Se Me ne se se ne e se Me ne ne se e no Se se xe xo xo e Blank line prompt 7 arguments Input filespec Output filespec Context Default filespec No related filespec STV field User flags Context work area No related filespec STV status return area User flags Move FAB address into R6 Move RAB address into R7 Set flag for sticky defaults Get input length Prompt for input Input descriptor Get input Retry on error Push descriptor address And length Allocate dynamic string Branch on error Call RTL Find File Routine Branch on error Skip on success Signal error status codes Display error Reenter filespec on error continued on next page Locating and Naming Files on Disks 5 9 Using One File Specification to Locate Many Files Example 5 2 Cont Selecting the USEROPEN Option to Call a Routine OPEN PUSHAL OFILED Display filespec CALLS 1 G LIBSPUT OUTPUT on screen MOVL OFILE R10 Move filespec address to R10 SFAB STORE FAB R6 FNA R10 FAC GET FNS OFILED SHR lt GET MSE gt SOPEN FAB R6 BLBS RO CONNECT PUSHL FABSL STV R6 PUSHL FABSL STS R6 CALLS 2 G LIBSSTOP Set read sharing global buffer Open the file Branch on success Push STV and STS in reverse order on stack to Sign
156. MS computes the size however this size may not be optimum If you decide to create an FDL file for defining an indexed file without using EDIT FDL you can approximate the value of the EXTENSION attributes You do this by multiplying the number of records per bucket by the number of records that you intend to add to the file during a given period of time To see the current default extension size use the DCL command SHOW RMS DEFAULT To set the default buffer count use the DCL command SET RMS_ DEFAULT EXTEND_QUANTITY n where n is the number of blocks per extension The corresponding field is FAB W_DEQ 9 2 3 2 Window Size If the file is extended repeatedly the extensions may be scattered on the disk Each extension is called an extent a pointer to each extent resides in the file header For retrieval purposes the pointers are gathered together in a structure called a window The default window size is 7 pointers but you can establish the window size to contain as many as 127 pointers You can also set the window size to 1 which makes a window that is just large enough to map the entire file Run Time Options 9 7 Run Time Options 9 2 Options Related to Opening and Closing Files When you access an extent whose pointer is not in the current window the system has to read the file header and fetch the appropriate window This is called a window turn and it requires an I O operation Window size is a run time option Many hi
157. MS to return a record having a record number equal to or greater than the specified record number For example when you specify record number 48 RMS returns record number 48 If RMS does not find record number 48 it returns the first record it encounters having a number greater than 48 The next key option FDL attribute CONNECT KEY GREATER THAN directs RMS to return the record that has the next greater record number For example when you specify record number 48 RMS returns record number 49 if record 49 exists You can also use random access mode to insert records into relative files You can even overwrite cells that contain records by selecting the update if option FDL attribute CONNECT UPDATE IF or by directly setting the RAB V UIF bit in the RAB L_ROP field 8 8 Record Processing Record Processing 8 4 Record Access for the Various File Organizations To access a relative file randomly by record number your program must contain the relative record number in the RAB at symbolic offset RAB L KBF and the key length value 4 at symbolic offset RAB B_KSZ 8 4 3 Processing Indexed Files Indexed files provide the most record processing flexibility Your program can read existing records from the file in sequential random access by RFA mode or random access by key mode RMS also allows you to write any number of new records into an indexed file if you do not violate a specified key constraint such as not allowing duplicate key values
158. N FIXED PROLOG Prolog Flags 0 PLG V NOEXTEND 0 First Data Bucket VBN 2 Maximum Record Number 2147483647 End of File VBN 10 Prolog Version 1 ANALYZE DOWN DATA BUCKET VBN 2 ANALYZE DOWN RECORD CELL VBN 2 offset X 0000 Cell Control Flags 2 DLC V DELETED 0 3 DCL V REC 1 Record Bytes 7 6 5 4 3 2 10 01234567 31 30 30 30 30 30 00 49 0000 1 000001 20 4C 41 54 49 47 49 44 0008 COMPAOL 4E 45 4D 50 49 55 51 45 0010 COMPUTER 52 4F 50 52 4F 43 20 54 0018 CORPORAT 31 31 20 4E 4F 49 54 41 0020 ION 42 20 54 49 50 53 20 30 0028 SPIT BRO 41 4F 52 20 4B 4F 4F 52 0030 OK ROAD 41 55 48 53 41 4E 20 44 0038 NASHUA 33 30 48 4E 20 20 20 20 0040 31 36 30 0048 62 If you use the REST command at the CELL AND RECORD level the utility will display all the cells and records in the file not just the cells and records in the current bucket 10 16 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics 10 1 6 Examining an Indexed File The structure of an indexed file also begins with the FILE HEADER FILE ATTRIBUTES and PROLOG structures From the PROLOG structure the file structure branches to the area descriptors and the key descriptors To branch to the area descriptor path specify the command DOWN AREA To branch to the key descriptor path specify DOWN KEY The area descriptor path contains structures that show information about the various areas in the file The key descr
159. NALYZE RMS FILE FDL command to create an output file analysis fdl file that reflects the current state of the data file The command syntax for creating the analysis fdl file follows ANALYZE RMS_FILE FDL OUTPUT analysis fdl file original data file The output file analysis fdl file contains all of the information and statistics about the data file including create time attributes and information that reflects changes made to the structure and contents of the data file over its life 10 26 Maintaining Files Maintaining Files 10 3 Optimizing and Redesigning File Characteristics For FDL optimization use the Edit FDL utility to produce an optimized output file optimized fdl file You can do this by modifying either the orginal FDL file original fdl file if available or the FDL output of the file analysis analysis fdl file Modification of an FDL file can be performed either interactively using a terminal dialogue or noninteractively by allowing the Edit FDL utility to calculate optimal values based on analysis information To optimize the file interactively using an OPTIMIZE script use a command with the following format EDIT FDL ANALYSIS analysis fdl file SCRIPT OPTIMIZE OUTPUT optimized fdl file original fdl file To optimize the file noninteractively use a command with the following format EDIT FDL ANALYSIS analysis fdl file NOINTERACTIVE OUTPUT optimized fdl file original fdl file The optimized fdl file parameter
160. NTIGUOUS EXTENSION CHANGES DATA AREA DATA FILL DUPLICATES INDEX AREA INDEX FILL LEVEL INDEX AREA NULL KEY PROLOG SEGO LENGTH SEGO POSITION TYPE CHANGES DATA AREA DATA FILL DUPLICATES INDEX AREA INDEX FILL LEVEL INDEX AREA NULL KEY SEGO LENGTH SEGO POSITION TYPE ANALYSIS OF AREA 0 RECLAIMED SPACE VMS 9 no 1 no 0 0 VMS ANALYZE RMS FILE Utility DISKSUSERWORK WORK RMS32 CUSTDATA DAT 4 indexed 520 50 system RWED owner RWED group RWED world no no yes carriage return variable 0 no no no 0 100 no 0 100 0 no 1 6 0 string no 0 100 yes 0 100 0 no 5 68 string continued on next page Maintaining Files 10 23 Maintaining Files 10 2 Generating an FDL File from a Data File Example 10 8 Cont KEY and ANALYSIS OF KEY Sections in an FDL File ANALYSIS OF KEY 0 DATA FILL DATA RECORD COUNT DATA SPACE OCCUPIED DEPTH B INDEX FILL INDEX SPACE OCCUPIED MEAN DATA LENGTH MEAN INDEX LENGTH ANALYSIS OF KEY 1 DATA FILL 1 DATA RECORD COUNT 3 DATA SPACE OCCUPIED 1 DEPTH E 1 DUPLICATES PER SIDR 1 4 1 1 8 MO rm 4 HF TD WwW UI Co INDEX FILL INDEX SPACE OCCUPIED MEAN DATA LENGTH MEAN INDEX LENGTH 10 3 Optimizing and Redesigning File Characteristics To maintain your files properly you must occasionally tune them Tuning involves adjusting and readjusting the characteristics of the file generally to make the file run fa
161. ON CHANGES DATA AREA DATA FILL DATA KEY COMPRESSION DATA RECORD COMPRESSION DUPLICATES INDEX AREA INDEX COMPRESSION INDEX FILL LEVEL INDEX AREA PROLOG SEGO LENGTH SEGO POSITION TYPE FDL Editor VMS indexed carriage return variable 0 8283 yes 18 2070 18 yes 18 string ADD command This is illustrated in Example 9 1 Example 9 1 Specifying Run Time Attributes Add Delete Exit Help OpenVMS FDL to insert one or more to remove one or more Editor lines into the FDL definition lines from the FDL definition to leave the FDL Editor after creating the FDL file to obtain information about the FDL Editor Q Invoke to initiate a script of related questions Modify to change existing line s in the FDL definition to abort the FDL Editor with no FDL file creation Quit Set View 9 2 Run Time Options to specify FDL Editor characteristics to display the current FDL Definition continued on next page Run Time Options 9 1 Specifying Run Time Options Example 9 1 Cont Specifying Run Time Attributes O Main Editor Function Keyword Help ADD Legal Primary Attributes ACCESS attributes set the run time access mode of the file AREA x attributes define the characteristics of file area x CONNECT attributes set various VMS RMS run time options DATE attributes set the data parameters of the file FILE attributes affect the entire VMS RMS data file JOURNAL attributes s
162. PROTECTION attribute 4 33 NAME attribute 6 3 9 6 NON FILE STRUCTURED attribute 9 14 ORGANIZATION attribute 4 32 OWNER attribute 4 33 PRINT ON CLOSE attribute 9 12 PROTECTION attribute 4 33 READ CHECK attribute 9 11 REVISION attribute 4 32 SEQUENTIAL ONLY attribute 9 10 SUBMIT ON CLOSE attribute 9 12 SUPERSEDE attribute 4 31 TEMPORARY attribute 4 31 USER FILE OPEN attribute 7 4 9 14 WINDOW SIZE attribute 9 8 9 9 WRITE CHECK attribute 9 11 FDL KEY section 4 33 DATA AREA attribute 3 25 DATA FILL attribute 3 26 INDEX AREA attribute 3 25 INDEX FILL attribute 3 26 LEVEL1 INDEX AREA attribute 3 25 TYPE attribute 3 23 FDL qualifier 10 22 FDL RECORD section BLOCK SPAN attribute 3 13 4 83 4 34 CARRIAGE CONTROL attribute 4 34 CARRIAGE RETURN attribute 4 33 count field format attribute 4 33 FORMAT attribute 4 34 Fortran attribute 4 33 Fortran carriage control attribute 4 33 MSB RECORD LENGTH attribute 4 33 PRINT attribute 4 33 PRINT carriage control attribute 4 33 SIZE attribute 4 33 FDL routines FDL CREATE routine 4 13 4 16 6 3 FDL GENERATE routine 4 13 FDL PARSE routine 4 13 6 3 9 1 example 9 22 to 9 23 FDL RELEASE routine 4 13 6 3 9 1 example 9 22 to 9 23 FDL SHARING attributes 7 4 7 6 7 24 Index 5 FID abbreviated names 6 20 restrictions 6 21 Fields 1 1 File ac
163. Processing 8 7 Synchronous and Asynchronous Operations User mode AST routines may be executed before the completion of a synchronous record operation see the OpenVMS Record Management Services Reference Manual If an AST routine attempts to perform operations on a record stream that is being called from a non AST level it must be prepared to handle stream activity errors RMS RSA or RMS BUSY 8 7 2 Using Asynchronous Operations To declare an asynchronous record operation you must set the asynchronous RAB V_ASY option in the RAB L_ROP field You can switch between synchronous and asynchronous operations during processing of a record stream by setting or clearing the RAB V_ASY option on a per operation basis You can specify completion routines to be executed as ASTs if success or error conditions occur Within such routines you can issue additional operations but they should also be asynchronous If they are not all other asynchronous requests currently active in your program cannot have their completion routines executed until the synchronous operation completes If an asynchronous operation is not completed at the time of return from a call to a service the completion status field of the RAB is 0 and a success status code of RMS PENDING is returned in Register 0 This status code indicates that the operation was initiated but is not yet complete Note Never modify the contents of an RMS control block when an operatio
164. Q DAT No exception file is created This program also returns the BRIEF CONVERT statistics DATA NAMES IN REC defines the input record OUT REC defines the output record STATVALUE receives the status value from the routine call NORMAL receives the value from SS NORMAL OPTIONS defines the CONVERT parameter list STATSBLK receives the CONVERT statistics The first data field NUM STATS contains the total number of statistics requested There are four 1 number of files processed NUM STATS 2 number of records processed NUM FILES 3 number of exception records NUM RECS 4 number of valid records NUM VALRECS IDENTIFICATION DIVISION PROGRAM ID PARTS ENVIRONMENT DIVISION CONFIGURATION SECTION SOURCE COMPUTER VAX OBJECT COMPUTER VAX INPUT OUTPUT SECTION FILE CONTROL SELECT IN FILE ASSIGN TO SEQ SELECT OUT FILE ASSIGN TO CUSTDATA DATA DIVISION FILE SECTION FD 01 FD IN FILE DATA RECORD IS IN REC IN REC 02 IN NUM PIC X 4 02 IN NAME PIC X 20 02 IN COLOR PIC X 4 02 IN WEIGHT PIC X 4 02 SUPL NAME PIC X 20 02 FILLER PIC X 28 OUT FILE DATA RECORD IS OUT REC continued on next page Creating and Populating Files 4 29 Creating and Populating Files 4 5 Populating a File Example 4 9 Cont Using the CONVERT Routines in a COBOL Program 01 OUT REC 02 OUT NUM PIC X 4 02 OUT NAME PIC X 20 02 OUT COLR PIC X 4 02 OUT WGHT PIC X 4 02 SUPL NAME PIC X 20
165. R2 labels you must specify MOUNT RECORDSIZE n at mount time The variable n denotes the record length in bytes Files without HDR2 labels were created by a system that supports only level 1 or 2 of the ANSI standard for magnetic tape labels and file structure Records should be fixed length because this is the only record format that either level supports If you do not specify a record size each block will be considered a single record Implementation Dependent Field The implementation dependent field contains two 1 character subfields that describe how the operating system interprets record format and form control The first subfield character position 16 denotes whether the RMS attributes are in this label or the HDR3 label If character position 16 contains a space the RMS attributes are in the HDR3 label if it contains any character other than a space character position 16 is the first byte of the RMS attributes in the HDR2 label The attributes appear in character positions 16 through 36 and 38 through 50 The second subfield the form control field at character position 37 specifies the form control that defines the carriage control applied to records within a file Possible values supported for RMS magnetic tape volumes are listed below A First byte of record contains Fortran control characters M The record contains all form control information Space Line feed carriage return combination is to be inserted between records when
166. RCW Data RCW Data Block 180 Bytes ZK 0354 GE Block Length Field The block length field denotes the maximum size of the blocks According to the ANSI magnetic tape standard valid block sizes range from 18 to 2048 bytes However the operating system allows you to specify a smaller or larger block size by using the BLOCKSIZE qualifier with the MOUNT command To specify the block size using RMS see the BLS field in the file access block FAB in the OpenVMS Record Management Services Reference Manual When you specify a block size outside the ANSI magnetic tape standard range the volume may not be processed correctly by other systems that support the ANSI magnetic tape standards 1 32 Introduction Introduction 1 3 Magnetic Tape Concepts Record Length Field The record length field denotes either the size of fixed length records or the maximum size of variable length records in a file Valid RMS record sizes vary depending on the record format The range for fixed length records is 1 to 65 534 bytes the range for variable length records is 4 to 9 999 bytes including the 4 byte RCW Therefore the maximum length of the data area of a variable length record is 9 995 bytes To comply with ANSI magnetic tape standards the record size should not be larger than the maximum block size of 2 048 bytes even though OpenVMS systems allow larger record sizes when the block size is larger For volumes containing files that do not have HD
167. REATE FILE THRU DISPLAY STATS STOP RUN CREATE FILE CALL FDLSCREATE USING BY DESCRIPTOR INDEXED FDL BY DESCRIPTOR NEWMASTER DAT BY DESCRIPTOR DEFAULT DAT BY DESCRIPTOR RESNAME BY REFERENCE FIDBLOCK BY VALUE 0 BY VALUE 0 BY VALUE 0 BY VALUE 0 BY VALUE 0 GIVING STATVALUE IF STATVALUE IS FAILURE CALL LIBSSTOP USING BY VALUE STATVALUE DISPLAY STATS DISPLAY The result filename is RESNAME CONVERSION DISPLAY FID number NUM CONVERSION DISPLAY FID sequence SEQ CONVERSION DISPLAY Volume number RVN CONVERSION 4 3 Creating and Accessing Tagged Files RMS supports the use of compound document text through the implementation of tagged files The term compound documents refers to files that contain a number of integrated components including text graphics and scanned images Tagged files are made distinguishable by the RMS file attribute stored semantics The value of the stored semantics attribute is called the file tag and it specifies how file data is to be interpreted RMS support for compound document text requires that compound document files be tagged with the appropriate stored semantics values These are binary values that can be up to 64 bytes long and can be expressed using hexadecimal notation The hexadecimal value of the DDIF tag for example is 2B0C8773010301 The operating system lets you assign names to tag values so that DCL commands such as DIRECTORY FULL and utilities such as FDL a
168. RS EERS 1 12 1 2 5 CD ROM Concepts see 1 14 1 2 5 1 CD ROM On Disc Formats 0 0000 eee 1 14 1 2 5 2 Volume Structure 0 es 1 14 1 2 5 3 Files 11 C D AGPS ense rex rm RR ek be eid 1 15 1 2 5 4 Using DIGITAL System Identifiers on CD ROM 1 16 1 3 Magnetic Tape Concepts llle 1 18 1 3 1 ANSI Labeled Magnetic Tape llle 1 19 1 3 1 1 Logical Format of ANSI Magnetic Tape Volumes 1 20 1 3 1 2 RMS Magnetic Tape Ancillary Control Process MTAACP 1 20 1 3 1 3 Basic Components of the ANSI Magnetic Tape Format 1 20 1 3 1 4 Volume and File Configurations llle eee 1 23 1 3 1 5 Volume Labels llleeeeeeeeee es 1 27 1 3 1 5 1 VOLT babel 202 x uen re eei d ed 1 27 1 3 1 5 2 VOL2 L bel i 24k43 RR ch REVUE RET EVE ETE 1 27 1 3 1 6 Header Labels llle 1 28 1 3 1 6 1 HDR Label ects wk eters ee x bor Bw aoe UR dor we 1 28 1 3 1 6 2 HDR2 Wiabel cc cae zie Se ee ha d ndr dans EUER RAE 1 31 1 3 1 6 3 HDR323 Label usse er deg Oa Sle oe aa ern er BOER es 1 34 1 3 1 6 4 HDR4 Label RR RR ER RE EI ER 1 34 1 3 1 7 Trailer Labels 2 22 eed oer oe uode uere mw E ue 1 34 1 4 Using Command Procedures to Perform Routine File and Device OpetratiOns 4 rao be 4 weak ap ette ed OR rni aes OR red rp bar aca 1 34 1 5 Volume Protection llle rhe 1 35 1 6 RMS Record Management Services llle ees 1 35 1 6 1 File Definition Lang
169. S FILE you can perform five functions e Inspect and analyze the internal structure of an RMS file e Generate a statistical report on the file s structure and use e Interactively explore the file s internal structure e Generate an FDL file from an RMS file e Generate a summary report on the file s structure and use ANALYZE RMS_FILE is particularly useful in generating an FDL file from an existing data file that you can then use with the Edit FDL utility also called the FDL editor to optimize your data files Alternatively you can provide general tuning for the file without the FDL editor To invoke the Analyze RMS_File utility use the following DCL command line format ANALYZE RMS FILE filespec The filespec parameter lets you select the data file you want to analyze For more information about the Analyze RMS File utility refer to Chapter 10 of this manual and the OpenVMS Record Management Utilities Reference Manual 1 7 2 The Convert Utility The Convert utility CONVERT copies records from one or more files to an output file optionally changing the record format and file organization to that of the output file Note that the Convert utility processes relative files by sequentially reading records from the input file then writing them to the output file As a result the relative record numbers RRN change when the input file contains deleted or unused records CONVERT is particularly useful in the tuning cycle of a
170. SB defn sys getdvi struct iosb printf strlen structure members must be adjacent sys getdvi item list one entry Locating and Naming Files on Disks 5 15 Locating and Naming Files on Disks 5 4 File Specification and Component Length Limits Main routine main static struct dsc descriptor DevNameDesc descriptor for device name buffer references char deviceName SYS SYSDEVICE device name string unsigned long ACP typeBuffer buffer for returned ACP type info from sys getdvi long retLen buffer for returned info length 4 from sys getdvi int status SYSSGETDVI return status struct iosb iosb 1 0 status block for SYSSGETDVI ITEM LIST 3 DVI_itemList item list for sys getdvi Initialize the descriptor for the device name string DevNameDesc dsc w length E strlen deviceName DevNameDesc dsc a pointer amp deviceName 0 Initialize the item list to request ACP type information from sys getdvi DVI_itemList bufflen DVI_itemList itemcode DVI itemList buffaddr sizeof ACP_typeBuffer DVI _ACPTYPE amp ACP_typeBuffer DVI itemList retlenaddr amp retLen DVI itemList terminator 0 status sys getdviw 0 efn not used 0 channel not used amp DevNameDesc device name descriptor by ref amp DVI itemList item list by ref amp iosb I O status block by ref 0 astadr not
171. Section 9 3 9 10 Run Time Options Run Time Options 9 2 Options Related to Opening and Closing Files Option Description Truncate on Put Update if Write behind When using sequential record access for sequential files only the record to be written is the last record in the file and RMS truncates the file just beyond that record e FDL CONNECT TRUNCATE ON PUT e RMS RAB L_ROP RAB V TPT If you set this option and your program tries to replace an existing record while adding records randomly to a file RMS modifies the existing record instead of replacing it When using this option for indexed files note that the file must not allow duplicates for the primary key Use this option carefully with a shared file see Section 8 1 e FDL CONNECT UPDATE IF e RMS RAB L_ROP RAB V_UIF See Section 9 2 3 Indicates an option that can be specified for each record processing operation For more information see Section 9 3 9 2 6 Options for Data Reliability The following table lists the run time file open options that apply to data reliability Option Description Read check Write check Specifies that transfers from volumes are to be checked by a read compare operation which effectively doubles the amount of disk I O performed This option is not available for all devices see the OpenVMS Record Management Services Reference Manual e FDL FILE READ_CHECK e RMS FAB L_FOP FAB V_R
172. The Delete service removes a record from the file You cannot delete individual records from sequential files but you can truncate sequential files using the Truncate service As with the Update service the Delete service must be preceded by a Find or Get service to establish the current record position When deleting records from an indexed file with alternate indexes you can specify the fast delete option to reduce the amount of time needed to delete a record When you invoke the Delete service and specify the fast delete option RMS does not attempt to remove any of the pointers from alternative indexes to the deleted record 8 4 Record Processing Record Processing 8 2 Primary Services You improve performance by postponing the processing needed to eliminate the pointers from alternative indexes to the record However there are disadvantages to using the fast delete option e The unused pointers from the alternate indexes result in a corresponding waste of space e Ifthe program later tries to access the deleted record from an alternate index RMS must traverse the pointer linkage find that the record no longer exists and then perform the processing that was avoided originally with the Delete service Use the fast delete option only if the immediate improvement in performance is worth the added space and overhead Typically you use the fast delete option for indexed files that implement alternate keys and require frequent maintena
173. The maximum bucket size is 63 blocks For indexed files the Edit FDL utility permits you to decide the bucket size for any particular index The data and index levels get the same bucket size but you can use the MODIFY command to change these values The Edit FDL utility calculates the default bucket size by first finding the most common index depth produced by the various bucket sizes If you specify smaller buffers rather than fewer levels the Edit FDL utility establishes the default bucket size as the smallest size needed to produce the most common depth On Surface Plot graphs these values are shown on the leftmost edge of each bucket size Edit FDL Utility Optimization Algorithms A 1 Edit FDL Utility Optimization Algorithms A 3 Bucket Size Note If you specify a separate bucket size for the Level 1 index it should match the bucket size assigned to the rest of the index The bucket size is always a multiple of disk cluster size The ANALYZE RMS FILE primary attribute ANALYSIS OF KEY now has a new secondary attribute called LEVEL1 RECORD COUNT that represents the index level immediately above the data It makes the tuning algorithm more accurate when duplicate key values are specified A 4 Global Buffers A 5 Index The global buffer count is the number of I O buffers that two or more processes can access This algorithm tries to cache or map the whole Key 0 index at least up to a point into memory for quicker
174. This default applies to all processes on a node in the cluster When you use this DCL command to establish the system default extension quantity it remains in effect until the node is rebooted You can also establish the system default extension quantity in a temporary or permanent fashion by appropriately setting the SYSGEN system parameter RMS EXTEND SIZE Performance Considerations 3 7 Performance Considerations 3 2 Tuning Volume Default Extension Quantity The volume default extension quantity can be permanently established when the volume is initialized with the INITIALIZE EXTENSION n command This default quantity is used whenever the volume is mounted To permanently change the volume default extension quantity you can use the SET VOLUME EXTENSION n command on a mounted disk To temporarily establish a volume default extension quantity or temporarily override the permanent volume default extension quantity use the MOUNT EXTENSION n command The new default is in effect until the volume is dismounted Unlike the other default quantities described that default to zero if not specified the volume default extension quantity defaults to 5 if not specified 3 2 1 3 3 Placement and Contiguity of Extends In addition to specifying the size of an extend you can specify other characteristics that affect the placement and contiguity of the extend When an application extends a file by calling the EXTEND service an Allocation XAB XAB
175. VBN 0 Current Extent Start 25 Blocks 3 Used 1 Next 26 Default Extend Quantity 1 Total Allocation 3 AREA DESCRIPTOR 7 VBN 3 offset X 01C0 continued on next page Maintaining Files 10 3 Maintaining Files 10 1 Viewing File Characteristics Example 10 1 Cont Using ANALYZE RMS FILE to Create a Check Report Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 28 Blocks 3 Used 1 Next 29 Default Extend Quantity 1 Total Allocation 3 KEY DESCRIPTOR 0 VBN 1 offset X 0000 Next Key Descriptor VBN 2 Offset X 0000 Index Area 1 Level 1 Index Area 1 Data Area 0 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 10 Key Flags 0 KEY V DUPKEYS 3 KEYSV IDX COMPR 4 KEYSV INITIDX 6 KEYSV KEY COMPR 7 KEY V_REC_COMPR rc ccc Key Segments 1 Key Size 4 Minimum Record Size 4 Index Fill Quantity 512 Data Fill Quantity 512 Segment Positions Segment Sizes 4 Data Type string Name PART NUM First Data Bucket VBN 4 KEY DESCRIPTOR 1 VBN 2 offset X 0000 Next Key Descriptor VBN 2 Offset X 0066 Index Area 3 Level 1 Index Area 3 Data Area 2 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 16 Key Flags 0 KEY V DUPKEYS 1 1 KEY V CHGKEYS 0 2 KEYSV NULKEYS 0 3 KEYS V IDX COMPR 0 4 KEYSV INITIDX 0 6 KEYS V KEY COMPR 0 Key Segments 1 Key Size 5 Minimum Record Size 9 Index Fill Quantity 512 Data F
176. YSTEM leadingfilenamechars 384 35200 0 txt 1 Such a file specification can be used as input to RMS with some limitations 6 5 1 Restrictions on FID Abbreviated Names A FID can be used for input to RMS but only the FID is significant The subset portion of the name component the type component and the version component are ignored by RMS As input the FID abbreviated file name component is not used as a default as from a related file specification to replace a wildcard in an output specification Instead the output specification will get a null file name as shown in the following COPY LOG U6666 U7777 U8888 U9999 05555 U6666 449 35295 0 txt l xxx COPY S COPIED DKA200 SYSTEM U6666 U7777 U8888 U9999 05555 U6666 449 35295 0 txt 1 copied to DKA200 SYSTEM xxx l Note that generated names with FIDs are possible only for resultant specifications which refer to specific files and not for expanded specifications which do not necessarily refer to one file 6 6 Using Process Permanent Files Process permanent files are files that remain open independent of image activation and rundown Process permanent files are created by setting the process permanent file bit FAB V PPF in the file processing options field FAB L_FOP When the bit is set RMS maintained internal data structures are allocated in the process control region of memory for the life of the process Thus process permanent files can remain open across image
177. a Sequential File User Program Read Next Record ZK 0747 GE There are limitations imposed by sequential access When accessing data sequentially a program can access a previous record only by reopening or rewinding the file or by switching to a random access mode See Chapter 8 for details Another limitation of sequential access is that you can add records only to the end of the file Sequential Access to Relative Files Relative files may be accessed sequentially even if some of the fixed length file cells are empty because records were never stored in them or because records were deleted from them RMS ignores empty cells and sequentially searches for the next occupied cell For example assume a relative file contains records only in cells 1 3 and 6 RMS responds to a sequential retrieval request by retrieving the record in cell 1 then the record in cell 3 and then the record in cell 6 Choosing a File Organization 2 3 Choosing a File Organization 2 1 Record Concepts Figure 2 2 shows how RMS checks each cell ignores an empty cell when it finds one and then checks the next cell for a record Figure 2 2 Sequentially Retrieving Records in a Relative File User Program Read Next Record ZK 0748 GE When storing records sequentially in a relative file RMS places each new record in the cell whose relative record number is one higher than the most recently accessed cell provided the cell is empty If the
178. a file is an ordered collection of logically related records treated as a unit One design consideration is the way records are transferred to your program from storage For disk files the smallest unit of transfer is a block but records are usually transferred in multiple blocks using transfer units that are primarily dictated by file organization If you use the sequential file organization the multiblock run time option allows multiple blocks to be transferred during a single I O operation Relative files and indexed files use buckets to transfer records A bucket is a storage structure consisting of 1 to 63 blocks used for building and processing relative and indexed files Choosing a File Organization 2 1 Choosing a File Organization 2 1 Record Concepts Another design consideration is how records are accessed the record access mode The record access mode specifies the way your program stores and retrieves file records A third consideration in designing files is how records are formatted The program that creates the file specifies its record format Any program that accesses the file must conform to the defined record format A fourth consideration is record layout The record layout defines the number and length of record fields For example a program that creates records in a payroll file might use a record layout containing the following fields e Employee name e Social security number e Pay rate e Deductions The next t
179. a portion of each record with a 2 byte binary count field in MSB format that specifies the length of the record in bytes excluding the count field itself D format Applies to variable length records in tape files To comply with the American National Standard X3 27 1978 Level 3 Magnetic Tape Labels and Record Formats for Information Interchange RMS stores a 4 byte decimal count field before the data field of each record on a magnetic tape volume In contrast to V format records the count field is considered as part of the record but before returning the count RMS adjusts it to include only the length of the record data When you create a file of variable length records specify the value in bytes of the largest record permitted in the file If you take the block span option the default the maximum variable length record size is 32767 bytes If you specify no block spanning the maximum variable length record size is 510 bytes For additional information about selecting the block span option see the OpenVMS Record Management Services Reference Manual Any attempt to store a record containing more bytes than the specified value results in an error If you specify a value of 0 any length record can be stored however you must consider the bucket capacity limitation defined for relative and indexed files Figure 2 6 compares fixed length record formats and variable length record formats as they apply to sequential files Each form
180. acter to represent the Unicode character that corresponds to the hexadecimal value 1234 Likewise the compound character is used to include the bracket as a character in a file or directory name rather than as the root or directory component delimiter And the compound character is used to represent the period as a character in a file or directory name rather than as the file type or the subdirectory delimiter The RMS escape character is always used to begin one of these compound characters Certain characters can be represented in more than one way as input to RMS Each character however will always be represented the same way in RMS s output no matter which representation was used for input The standard representation for each character is known as its canonical form For example the input specifications File 37 Txt and File U0037 Txt would appear in output as File7 Txt The ASCII encoding of the numeral 7 is the hexadecimal value 37 Note The use of compound characters in RMS is allowed only on Alpha systems running OpenVMS Version 7 2 The use of ODS 5 characters that are not also ODS 2 characters is allowed only on ODS 5 disks accessed from Alpha systems running OpenVMS Version 7 2 When RMS outputs a file specification as a resultant name for example it follows the rule that other ISO Latin 1 8 bit characters that have no graphical representation or which are used for control functions by ot
181. activations SYS COMMAND SYS INPUT SYS OUTPUT and SYS ERROR are all opened in this manner by the LOGINOUT command image The DCL command OPEN also opens files in this manner With user mode code you can access process permanent files only indirectly RMS provides a subset of the total available operations to the indirect accessor Indirect accessors gain access to process permanent files through the logical name mechanism as follows 1 The LOGINOUT command image or at a later point the command interpreter opens or creates a file corresponding to the process s command input output and error message streams Logical names are created in the process logical name table for S YS COMMAND SYS INPUT SYS OUTPUT and SYS ERROR respectively The equivalence string for the logical name has a special format that indicates the correspondence between the logical name and the related process permanent file For more detail concerning the equivalence string format for logical names see the discussion of logical name services in the OpenVMS System Services Reference Manual For example for an interactive user these single process permanent files are opened for the terminal Advanced Use of File Specifications 6 21 Advanced Use of File Specifications 6 6 Using Process Permanent Files When an indirect accessor opens or creates a file specifying a logical name that has one of these special equivalence strings RMS recognizes this and therefore
182. after which an error is returned when you choose the wait if locked option The number of seconds is specified by the CONNECT TIMEOUT_PERIOD or RAB B_ TMO field to eliminate a potential deadlock e FDL CONNECT TIMEOUT PERIOD e RMS RAB L_ROP RAB V_TMO and RAB B_TMO Specifies the address of the user buffer that receives the record Applies to the Get service only e FDL None e RMS RAB L_UBF Run Time Options 9 17 Run Time Options 9 3 Summary of Record Operation Options Option Description User buffer size Wait if locked Specifies the maximum length of the user record buffer Applies to the Get service only FDL None RMS RAB L USZ Specifies that if the record is locked RMS must wait until it is available also allows use of the wait timeout period option FDL CONNECT WAIT FOR RECORD RMS RAB L ROP RAB V WAT 9 3 2 Put Service Options The Put service or equivalent language statement adds a record to the file The options associated with the Put service are summarized in the following table These options can be set for each Put service if the program can access the appropriate RAB control block fields The RAB control block fields are preset by connect time values or defaults and as a result of previous service calls Option Description Asynchronous record processing Key buffer Key size Load buckets 9 18 Run Time Options Specifies that record I O for this record stre
183. ail the process that RMS uses to compose fully qualified file specifications from user input and from application input Note This chapter documents file specifications as presented at the RMS interface such as RMS services SYS OPEN and SYS SEARCH For details on specifications at the ACP XQP interface such as the system service SYS QIO refer to the OpenVMS I O User s Reference Manual As of OpenVMS V7 2 RMS on Alpha systems has been extended to support disk file specifications of greater length and with a larger character set than was supported on prior versions and than is supported on VAX platforms Some of the extended features can be used on existing ODS 2 structure level disks Many features are available only on ODS 5 structure level disks Throughout this chapter behaviors that differ depending upon the architecture Alpha or VAX or upon the target device ODS 5 disk or ODS 2 disk are so marked in the text 5 1 Understanding Disk File Specifications A disk file specification on an OpenVMS system consists of up to seven components several of which assume default values when they are not specified To allow RMS to identify the boundaries of each component certain characters separate the components in a file specification These characters mark the beginning or the end of a file specification component and allow RMS to identify missing components for which defaults can be substituted A complete file specification takes th
184. al error and stop me se Me we Se Ne This block of code attempts to Connect with global buffers if possible and uses local buffers if global buffer resources are not available Because the global buffer value is set between the Open and Connect all defaults are overwritten Li Li T Li Li T C ONNECT MOVL 15 R9 R9 contains global buffer count BRB RETRY Skip local buffer handling LOCAL MOVL 0 R9 Turn off global buffers SRAB STORE RAB R7 MBF 6 PUSHAL LOC P CALLS 1 G LIBSPUT OUTPUT RETRY SFAB STORE FAB R6 GBC R9 SCONNECT RAB R7 Request 6 local buffers Inform user No global buffers Override default global buffer Connect the record stream e Me Me Me se we Se Se we we BLBC RO RERR Branch on error BRW DONE On success return RERR CMPL RO RMS CRMP Test if too many global buffers BNEQ CERR Quit if other error CMPL 4 R9 Test if too few global buffers BLSS LOCAL Use local buffers SUBL2 13 R9 Decrement R9 by 3 BRW RETRY Attempt Connect again CERR PUSHL RABSL STV R7 Push STV and STS in reverse PUSHL RABSL STS R7 order on stack to CALLS 2 G LIBSSTOP Signal and end on error DONE RET Return to main program END Example 5 2 also shows the proper way to signal errors The RAB L STS completion status field and the RAB L_STV additional status values field of the FAB or RAB are used so that secondary completion information is displayed if appropriate by the LIB SIGNA
185. alue and random access by RFA to set the current record position using a Find service at the first record of the desired account number It can then switch to sequential record access and read all successive records for that account until the account number changes or the end of the file is reached Figure 8 1 shows how the file is accessed for account C Figure 8 1 Using RFA Access to Establish Record Position User Program Read First Record in Account C by RFA Switch Access Mode to Sequential Read Remaining C Records ZK 0753 GE 8 14 Record Processing Record Processing 8 5 Block Input Output 8 5 Block Input Output Block input output I O lets you bypass the record processing capabilities entirely In this manner your program can process a file as a virtually contiguous set of blocks Block I O operations provide an intermediate step between operations and direct use of the Queue I O Request system service Using block I O gives your program full control of the data in the individual blocks of a file while being able to take advantage of the RMS capabilities for opening closing and extending a file In block I O a program reads or writes one or more blocks by specifying a starting virtual block number in the file and the length of the transfer Regardless of the organization of the file RMS accesses the identified block or blocks Because RMS files contain internal information meaningful only to RMS itself Compaq
186. am is done asynchronously e FDL CONNECT ASYNCHRONOUS e RMS RAB L_ROP RAB V_ASY Specifies key buffer that must contain the desired record s relative record number when adding records randomly to a relative file e FDL None e RMS RAB L_KBF Specifies a field that must have a value of 4 the default value provided by RMS when adding records to a relative file using random record access e FDL None e RMS RAB B KSZ Fills the buckets to the level specified when the file is created The default is that buckets fill completely before a bucket split occurs e FDL CONNECT FILL_BUCKETS e RMS RAB L_ROP RAB V_LOA Run Time Options 9 3 Summary of Record Operation Options Option Description Read allowed Record access Record header buffer Record buffer address Record buffer size Timeout period Allows the locked record being written to be read e FDL CONNECT LOCK ON WRITE e RMS RAB L ROP RAB V RLK Specifies the way records are added sequentially according to ascending key value or relative record number randomly by key indexed files or by record number relative files or randomly by RFA e FDL None e RMS RAB B RAC values RAB C_SEQ RAB C_KEY RAB C RFA Contains the symbolic address of the record header buffer that contains the fixed portion of a VFC record Applies to the Get service only e FDL None e RMS RAB L_RHB Specifies the address of the record buffer that contains t
187. ample A hyphen at the end of a command format description command line or code line indicates that the command or statement continues on the following line XV numbers All numbers in text are assumed to be decimal unless otherwise noted Nondecimal radixes binary octal or hexadecimal are explicitly indicated xvi 1 Introduction This chapter illustrates how basic data management concepts are applied by the OpenVMS Record Management Services OpenVMS RMS referred to hereafter as RMS RMS is the data management subsystem of the operating system In combination with OpenVMS operating systems RMS allows efficient and flexible storage retrieval and modification of data on disks magnetic tapes and other devices RMS may be implemented through the File Definition Language FDL interface or through high level language program specific processing options Although RMS supports devices such as line printers terminals and card readers the purpose of this guide is to introduce you to RMS record keeping on magnetic tape and disk In contrast to magnetic tape storage disk storage allows faster data access while providing the same virtually limitless storage capacity Disks provide faster access because the computer can locate files and records selectively without first searching through intervening data This faster access time makes disks the most appropriate medium for online file processing applications 1 1 File Concepts
188. ams that use shared files must handle record locking conflicts that may occur when two or more record streams try to access the same record File Sharing and Buffering 7 13 File Sharing and Buffering 7 2 Record Locking RMS provides three options for handling record locking conflicts e You can have the application program handle the record locked error status RMS RLK returned by RMS when a record stream is denied access to a record e You can have the requesting service wait for access wait if locked option e You can have the requesting service ignore the lock read regardless option The following table lists the options for having RMS handle record locking conflicts and how you select each option through the FDL and RMS interfaces Option Interface How to Select Wait if locked FDL CONNECT WAIT FOR RECORD RMS RAB L ROP RAB V WAT Wait timeout FDL CONNECT TIMEOUT ENABLE and period CONNECT TIMEOUT PERIOD RMS RAB L ROP RAB V TMO and RAB B_TMO Read FDL CONNECT READ REGARDLESS regardless RMS RAB L ROP RAB V RRL The following sections describe each of these options 7 2 3 4 Handling the Record Locked Error When a service is denied record access because of a record conflict it returns a record locked error status RMS RLK that indicates the access attempt failed because the record was locked One option is to have the application program pause briefly and then try again to access the record Example 7 1 conta
189. and 10 11 Home blocks 1 8 Index 7 I O and performance 3 1 I O unit 3 9 to 3 13 Identifier fields file 1 28 file set 1 30 implementation 1 27 owner 1 27 volume 1 27 Image activations 5 17 INDEX BUCKET structure 10 18 Index compression prohibition against using 4 8 restrictions 3 2 3 19 3 26 Index depth A 2 Indexed files 2 19 3 18 advantages of using 2 25 allocating A 1 alternate key 2 20 bitmap 1 9 bucket size 3 10 3 25 7 21 A 1 buffering 7 21 7 22 compression 3 2 3 19 3 26 deferred write option with 3 12 designing 3 18 to 3 28 disadvantages of using 2 25 examining 10 17 extend size 3 6 fill factor 3 10 global buffers 7 22 INDEXFESYS 1 8 key type 2 20 making contiguous 10 28 optimizing performance 3 18 to 3 28 organization 1 2 primary key 2 20 Prolog 1 files and Prolog 2 files 3 19 reclaiming buckets in 10 28 record access 8 9 to 8 14 redesigning 10 25 reorganizing 10 28 run time options 9 12 9 13 selection of default extension quantity 3 6 tuning 3 18 to 3 28 with global buffers 3 28 INDEXED qualifier 7 22 Index entries ordering 2 5 Index levels number of A 2 Index structures 3 18 3 25 Level 0 3 20 Level 1 3 20 primary 3 20 INDEX AREA attribute 3 25 INITIALIZE command window size and 9 8 Index 8 INTERACTIVE qualifier 10 11 Internal buffers 8 3 Interrecord gap See IRG INVOKE command 4 5 IRG interrecord
190. and a 3 character generic match RMS returns the record with key value ABC e Ifthe program uses the equal or next key option with ascending sort order and a 2 character generic match RMS returns the record with key value ABA Now observe the effects of varying the search key option and the length of the generic string e If the program uses the next key option with descending sort order and a 3 character generic match RMS again returns the record with key value ABA e If the program uses the next key option with descending sort order and a 2 character generic match AB RMS returns a record not found condition because none of the records has a key that begins with the letters AA Now consider an example of how to return all the records in a file with key values that match the generic string AB 1 Specify the generic string value of AB 2 byte key in random access by key mode Use the Get service or the Find services to access the first record Change the record access mode to sequential Access the next record um w p Compare the first two characters of the returned record s key with the first two characters of the specified key Record Processing 8 13 Record Processing 8 4 Record Access for the Various File Organizations 6 Ifthe two key values are the same process the record and return to step 4 If the two keys differ do not process the record instead proceed to the next task may require changing back to ra
191. and more efficient access Depth The indexed design routines simulate the loading of data buckets with records based on your data regarding key sizes key positions record sizes mean and maximum compression values load method and fill factors When the Edit FDL utility finds the number of required data buckets it can determine the actual number of index records in the next level up each of which points to a data bucket The process is repeated until all the required index records for a level can fit in one bucket the root bucket When a file exceeds 32 levels the Edit FDL utility issues an error message With a line plot the design calculations are performed up to 63 times once for each legal bucket size With a surface plot each line of the plot is equivalent to a line plot with a different value for the variable on the Y axis A 2 Edit FDL Utility Optimization Algorithms Glossary This glossary defines terms used in this manual accessor A process that accesses a file or a record stream that accesses a record alternate key An optional key within the data records in an indexed file used by RMS to build an alternate index See also key indexed file and primary key area An RMS maintained region of an indexed file It allows you to specify placement or specific bucket sizes or both for particular portions of a file An area consists of any number of buckets and there may be from 1 to 255 areas in a file
192. ant MONITOR recording files to obtain a complete record of RMS activity If this display represents a period of activity that the system manager or application developer wants to optimize then the following observations can be derived The number of Active Streams connected to this file and the cache attempt rates verify that this is a very active file that could benefit from performance analysis Global buffer utilization is very good as indicated by Global Cache Hit Percent The relatively few global buffer read I Os and complete absence of global buffer write I Os might be due to the fact that index buckets tend to be placed in global buffers Index buckets are often read but seldom written Generally global buffer I O activity can be reduced by adding global buffers However excessive use of global buffers can increase the elapsed time for RMS operations as measured in the application The Run Time Library timer routines can be used to measure elapsed time for RMS operations You can derive an optimal number of global buffers by varying the number and then evaluating the global buffer I O rates against elapsed time per operation Local buffer read and write I O rates indicate that the application might be saturating the capacity of the disk RA81 You can verify this by running the MONITOR DISK option clusterwide and examining the queue length for the disk involved It might help to spread the file over more than one disk There is a te
193. aring conditions no sharing sharing without interlocking and sharing with interlocking Chapter 7 discusses each of these in detail 3 1 4 Impact on Applications Design The impact on applications design increases as file design complexity increases That is your application programs require more design effort for processing indexed files than for processing sequential files The primary consideration here should be to evaluate whether the benefits derived by having direct access to records is worth the added cost of the application program design needed to interface with the file management system 3 2 Tuning The process of designing your files to achieve better processing performance is called tuning Tuning requires you to make a number of trade offs and design decisions For example if a process had sole access to the processor it could keep all of its data in memory and tuning would be unnecessary but this situation is unlikely Instead several processes are usually running simultaneously and are competing for the memory resource If all processes demand large amounts of memory the system responds by paging and swapping which slows down system performance The way you intend to use your programs and data files can determine some of the basic tuning decisions For example if you know that three files are accessed 80 percent of the time you might consider locating the files in a common area on the disk to speed up access to them
194. at shows a portion of a file that contains three records The comparable record in each format contains the same number of bytes The first record has 8 bytes the second 16 and the third 24 For the fixed length record format the record length is set at 32 bytes Therefore RMS considers all 32 bytes to be used 2 10 Choosing a File Organization Choosing a File Organization 2 1 Record Concepts Figure 2 6 Comparison of Fixed and Variable Length Records Fixed Length D Format Variable Length Tape V Format Variable Length Disk 32 Bytes 32 Bytes 32 Bytes T T T I Li 1 I i 1 I i 1 I i I 1 8 16 24 Bytes I Bytes Bytes I i I L L L MN a Count Fields T T T i I i I 1 Li i i i 1 8 1 16 1 24 Bytes 1 Bytes i Bytes i i i i i i IH 1 i L 1 L bS es Count Fields RMS considers all 32 bytes to be used even though they may not contain useful information in the eyes of the user ZK 0754 GE Clearly variable length records can save space but if records are updated in place you should consider trading off some space efficiency for update flexibility All records in a relative file are in fixed length cells Here variable length records do not save space in fact the two count field bytes prefixing each record actually consume additional space In the indexed file organization the capacity of the data bucket and the maximum record size limit record length 2
195. ation FDL GENERATE Produces an FDL specification by interpreting a set of control blocks It then writes the FDL specification either to an FDL file or to a character string FDL PARSE Parses an FDL specification allocates control blocks and then fills in the relevant fields FDL RELEASE Deallocates the virtual memory used by the control blocks created by FDL PARSE You must use FDL PARSE to fill in to populate the control blocks if you plan to release the memory with FDL RELEASE later Because the FDL GENERATE FDL PARSE and FDL RELEASE routines allow you to use the run time as well as the creation time features of RMS you must call them from a language that can access the control block fields that specify the CONNECT options This may be difficult from a high level language Example 4 3 shows how to call the FDL PARSE and FDL GENERATE routines from a Pascal program Creating and Populating Files 4 13 Creating and Populating Files 4 1 File Creation Characteristics Example 4 3 Using FDL Routines in a Pascal Program INHERIT SYSSLIBRARY STARLET PROGRAM example2 input output order master This program fills in its own FAB RAB and XABs by calling FDLSPARSE and then generates an FDL specification by calling FDLSGENERATE It requires an existing input FDL file TESTING FDL for FDLSPARSE to parse TYPE FDL CALL INTERFACE CONTROL FLAGS o ok oo BIT1 BIT
196. bit for write behind processing prior to requesting the Connect service You can also use FDL to select these options by using the secondary CONNECT attributes READ AHEAD and WRITE BEHIND respectively As of OpenVMS Alpha Version 7 3 1 a new RMS system feature related to write behind was implemented Write Behind Option as a System Default A dynamic SYSGEN parameter RMS SEQFILE WBH can be used to externally request RMS to implement the write behind feature as a system default See the OpenVMS System Manager s Manual If this system option is set RMS implements the existing RMS user write behind option as a system default regardless of the RAB L_ROP RAB V_WBH setting whenever write access is requested for an unshared sequential file opened for image I O This feature is a system option It is not the default for the following reasons 1 Enabling write behind involves a change in error reporting that could affect some application a write error may be reported for a subsequent operation rather than for the write the error occurred on 2 The allocation of an additional RMS intermediate buffer may result in more page faulting if process working set quotas are insufficient 3 4 Tuning a Relative File A relative file consists of a file header file attributes a prolog and a series of fixed length cells Each cell contains one record that includes a deleted record byte followed by the data portion of the record which may or may not
197. bit in the FAB L_RAT field 3 3 2 Multiblock Size Option A multiblock is an I O unit that includes up to 127 blocks but can be used only with sequential files When a program instructs RMS to fetch data within a multiblock the entire multiblock is copied from disk to memory Performance Considerations 3 13 Performance Considerations 3 3 Tuning a Sequential File You specify the number of blocks in a multiblock using the multiblock count a run time option If you are using the FDL editor specify the multiblock count option using the secondary CONNECT attribute MULTIBLOCK COUNT From a lower level language you may set the value into the RAB B MBC field directly Another alternative is to establish the count using a DCL command of the following form SET RMS_DEFAULT BLOCK_COUNT n The variable n represents the specified number of blocks Here the specified multiblock count is limited to your process unless you specify the SYSTEM qualifier In most cases the largest practical multiblock value to specify is the number of blocks in one track of the disk a number that varies with the various types of disks See the OpenVMS I O User s Reference Manual for the supported track sizes However the most efficient number of blocks for your application may be more or less than the number of blocks in a track You should try various sizes of multiblocks until you find the optimum value 3 3 3 Number of Buffers For sequential files you
198. buffers are charged against each process s working set size The guideline for using global buffers is the same as the guideline for using local process I O buffers Global buffers only provide significant benefits if more than one process refers to the same bucket in the global cache If bucket contention is high I O transfers can be minimized and performance improved However global buffers do not always improve performance For example multiple processes independently reading records and using sequential access are most apt to refer to separate buckets In that case bucket contention is low and the number of I O transfers is not reduced so global buffers do not improve performance 3 5 2 5 Using the Deferred Write Option The deferred write option is a run time option that can improve performance It is the default operation for some high level languages and can be specified by clauses in other high level languages If there is no language support you can call VAX MACRO subroutine that sets the FAB L_FOP field the FAB V_DFW option When you select the deferred write option RMS delays writing a modified bucket to the disk until the buffer is needed to read another bucket into the cache or until another process needs to reference the modified bucket If a subsequent operation references the bucket before it is flushed out to disk then one I O operation has been eliminated Typically the largest performance gains come from using the def
199. cates to which Files 11 On Disk Structure level they pertain Table 1 5 Files 11 Control Files Reserved File File Name Structure Structure Level 1 Level 2 Index file INDEXFSYS 1 X X Storage bit map file BITMAP SYS 1 X X Bad block file BADBLK SYS 1 X X Master file directory 000000 DIR 1 X X Core image file CORIMG SYS 1 X X Volume set list file VOLSET SYS 1 X Continuation file CONTIN SYS 1 X Backup log file BACKUPSYS 1 X Pending bad block BADLOG SYS 1 X Security profile SECURITY SYS X All the files listed in Table 1 5 are listed in the master file directory MFD 000000 Index File Every Files 11 volume has an index file which is created when the volume is initialized This index file identifies the volume to the operating system as a Files 11 structure and contains the access data for all files on the volume The index file which is listed in the master file directory as INDEXF SYS 1 contains the following information e Bootstrap block The volume s bootstrap block is virtual block number 1 of the index file If the volume is a system volume this block contains a bootstrap program that loads the operating system into memory If the volume is not a system volume this block contains a program that displays the message that the volume is not the system device but a device that contains user files only Introduction 1 2 Disk Concepts e Home block The home block provides specific information about the v
200. ccess control lists ACLs Creating and Populating Files 4 25 Creating and Populating Files 4 4 Defining File Protection 4 4 1 UIC Based Protection You can protect the disk with UIC based protect codes that are described in the OpenVMS Guide to System Security The owner UIC is normally the UIC of the person who created the file The protection code indicates who is allowed access and what type of access they are permitted When you try to open a file your UIC is compared to the owner UIC of the file Depending on the relationship of the UICs you might be classified under one or more of the following categories e System e Owner e Group e World Depending on your classification you may be allowed or denied the following types of access Read Can examine print or copy a disk or tape file Write Can modify or write to a disk or tape file Execute Can execute a disk file that contains executable program images Delete Can delete a disk file You can specify the UIC based protection value you need when the file is created if you use either an FDL specification or RMS directly After you create a file you can change its UIC based protection with the DCL command SET PROTECTION For more information about the SET PROTECTION command see the OpenVMS DCL Dictionary The previous list omits CONTROL access because it is never specified in the standard UIC based protection code However CONTROL access can be specified in an ACL an
201. ccess mode When finding records in random access by key access mode your program can specify any one of the four types of key matches exact generic approximate generic approximate described in Section 2 1 1 2 and Section 8 4 3 2 In addition to reading writing and finding a record your program can delete or update any record in an indexed file if the operation does not violate specified key characteristics For example if the program specifies that key values cannot be changed any update that attempts to change a key value is rejected Record Processing 8 11 Record Processing 8 4 Record Access for the Various File Organizations The next section describes how indexed files are used with the sequential and random access by key modes 8 4 8 1 Sequential Access You can use sequential record access mode to retrieve successive records in an indexed file RMS retrieves the records in successive order by the specified sort order for a key of reference The key of reference for example primary key first alternate key second alternate key and so forth is established through one of the following services e The Connect service e The Rewind service e The Find service or the Get service using random access Note that a Get or Put service specifying random access by RFA always establishes the key of reference as the primary key When the sequential access mode is used with the Put service to insert records into an indexed fil
202. ccess mode switching Term applied to the switching from one type of record access mode to another while processing a file Glossary 5 Glossary 6 record blocking The technique of grouping multiple records into a single block On magnetic tape an IRG is placed after the block rather than after each record This technique reduces the number of I O transfers required to read or write the data and in addition for magnetic tape it increases the amount of usable storage area Record blocking also applies to disk files record cell A fixed length area in a relative file that can contain a record Fixed length record cells permit RMS to directly calculate the record s actual position in the file record file address RFA The unique address RMS returns to your program whenever it accesses a record Using the RFA your program can access disk records randomly regardless of file organization The RFA is valid only for the life of the file and when an indexed file is reorganized each record s RFA will typically change record format The way a record physically appears on the recording surface of the storage medium The record format defines the method for determining record length record length The size of a record in bytes record locking A facility that prevents access to a record by more than one record stream or process until the initiating record stream or process releases the record Record Management Services See RMS R
203. ce On Alpha systems a system service SYS CVT FILENAME is available to convert names between their RMS interface form and their ACP XQP on disk form See the OpenVMS System Services Reference Manual A GETUAI for details on its use 5 2 5 The Root Component The root component of a file specification begins with an open square bracket or an open angle bracket and ends with a period followed by a closing square bracket or a closing angle bracket gt A root that begins with a square bracket must end with a square bracket and a root that begins with an angle bracket must end with an angle bracket The root component contains a series of root subdirectory names separated by periods Examples of legal root components are RLEVELO RLEVELO RLEVEL1 RLEVELO RLEVEL1 RLEVEL2 RLEVELO RLEVEL1 Note An alternate form of root subdirectory name supported by RMS only on Alpha systems on both ODS 5 and ODS 2 disks is that of a directory ID referred to as DID This form is described in Chapter 6 A root subdirectory name may contain a period To be distinguishable from the delimiter periods it must be specified to RMS as 5 2 6 The Directory Component The directory component of a file specification begins with an open square bracket or an open angle bracket and ends with a closing square bracket or a closing angle bracket gt A directory compon
204. ce With sequential access the Find service permits you to skip over records With either random access by relative record number or random access by RFA the Find service establishes a starting point for sequential Get services You cannot randomly delete records from a sequential file However you can randomly update records in a sequential file if the file is on disk and if the update does not change the record size The following sections discuss the use of sequential and random access modes with sequential files 8 4 1 1 Sequential Access The sequential access mode is supported for sequential files on all devices It is the only record access mode that is supported for nondisk devices such as terminals mailboxes and magnetic tapes With sequential access RMS returns records from sequential files in the order in which they were stored When a program has retrieved all of the records from a sequential file any further attempt to sequentially access records in the file causes RMS to return an end of file no more data condition code In sequential access mode you can add records only to the end of a sequential file that is the file location immediately following the current record position 8 4 1 2 Random Access You can use the relative record number to randomly retrieve and insert records in sequential files having fixed length records Records are numbered in ascending order starting with number 1 In a sequential file re
205. cell is not empty the new record cannot be stored in it Instead RMS returns an error status As Figure 2 3 shows the program directs RMS to store record F in cell 2 Record A already occupies cell 1 but cell 2 is empty so RMS can store the record in this cell If this request is followed by a request to sequentially store the next record RMS stores the record in cell 3 which is also empty However if the program tries to store a new record in the next cell which already contains record B the attempt fails Note that although RMS cannot store a new record in a cell that is already occupied your program can modify the record occupying the cell 2 4 Choosing a File Organization Choosing a File Organization 2 1 Record Concepts Figure 2 3 Sequentially Storing Records in a Relative File Cell 1 start User Program of file Write record F to cell 2 Pd File after Fi write operation Cell 2 now contains record F ZK 0749 GE Sequential Access to Indexed Files When a program sequentially accesses an indexed file RMS uses one or more indexes to determine the order in which to process the file records Because index entries are ordered by key values an index represents a logical ordering of the records in the file If you define more than one key for the file each index associated with a key represents a different logical ordering of the records in the file Your program can then use the sequential access mode
206. cess Processing Relative Files Sequential Access Random Access Processing Indexed Files Sequential Access Random Access Access by Record File Address RFA 0000 cece eens Block Input Output Current Record Context Current Record Position Next Record Position Synchronous and Asynchronous Operations 0000 eee eee Using Synchronous Operations sls Using Asynchronous Operations 0c cee e eee eee 9 Run Time Options viii 9 1 9 1 1 9 1 2 9 2 9 2 1 9 2 2 9 2 3 9 2 3 1 9 2 3 2 9 2 3 3 9 2 4 9 2 5 9 2 6 9 2 7 9 2 8 Specifying Run Time Options Using the Edit FDL Utility 0 00 0 000 0c eee Using Language Statements and RMS 0005 Options Related to Opening and Closing Files 08 File Access and Sharing Options 0 0 c ee ee eee eee File Specifications File Performance Options Extension Size Window Size Summary of Performance Options llli ees Record Access Options Options for Adding Records 0 00 cc eect eee nes Options for Data Reliability llle Options for File Disposition 0 0 0 0 cece ee ees Options for Indexed Files 7 17 7 17 7 18 7 20 7 20 7 21 7 22 7 24 PpP ee gee Gee ep Ge ge cae Gu P o Eod g OMDOAONDUAUAANNOWAONNNOAAHKAKWNH 2 Cre ee Cee Ces Cree Cree Cee
207. cess blocks FAB See FABs File access sensing tags 4 23 FILE ATTRIBUTES structure 10 12 10 15 10 17 File characteristics 4 31 4 32 File corruption 10 2 File default extension quantity 3 5 with multiple areas 3 7 File Definition Language See FDL File design attributes 3 4 File disposition 9 11 File extends See Extends File header labels See Header labels File headers 1 9 Files 11 structure 1 9 FILE HEADER structure 10 12 10 15 10 17 File identifier field 1 28 File names 5 9 File opening options See also Creation time options adding records 9 10 9 11 data reliability 9 11 file access and sharing 9 6 file disposition 9 11 file performance 9 7 to 9 10 file specification 9 6 9 7 for indexed files 9 12 9 13 for magnetic tape processing 9 13 9 14 for nonstandard file processing 9 14 record access 9 10 File organization See also Indexed files Relative files Sequential files File organization option 4 32 File positioning 4 34 File processing many files 5 28 to 5 29 nonstandard file 9 14 single file 5 27 to 5 28 File protection 4 32 Files 1 1 See also File protection File sharing File structures Indexed files accessing category summary 4 26 defaults 7 5 in an OpenVMS Cluster 3 33 options 4 26 aligning 3 16 Index 6 Files cont d contiguity 3 4 3 25 extensions 3 24 FDL 4 2 4 15 10 1 10 22 header 3 15 3 18 10 11 ini
208. ch record e A count field for each variable length record e Other overhead of varying lengths that is needed by RMS to move files and to delete records You should keep the size of records to the minimum required for your application You should also consider the effects of compression on the size of your indexed files You can compress keys in data buckets and in index buckets and you can compress data in the primary buckets If you use key index or data compression the file requires less space on the disk and each I O buffer can hold more information Compression may even eliminate one index level thereby reducing the number of disk transfers needed for random access 3 2 Performance Considerations Performance Considerations 3 1 Design Considerations Note You cannot use key compression or index compression with the collated key data type Random access of compressed files requires slightly more CPU time but this is usually offset by the improved performance you achieve with fewer index levels 3 1 3 Shared Access A file management technique that allows more than one user to simultaneously access a file or a group of files is called shared access or file sharing When you try to adjust the performance of shared files you need to pay particular attention to record locking options and the use of global buffers Avoid assigning sharing attributes to files that are not actually shared There are essentially three sh
209. completion status indicating the record is locked RMS RLK If the record has a write lock the requesting service reads the record and returns a completion status indicating that the record was locked but a read was permitted RMS OK RLK If you specify the no locking option together with the manual unlocking option the no locking option takes precedence That is if you specify both options to the service that accesses the record the service returns control to the application program with the record unlocked See Section 7 2 4 1 for a description of the manual unlocking option 7 2 2 5 No Query Record Locking Option Alpha Only The OpenVMS operating system provides functionality that can minimize record locking for read accesses to shared files thereby avoiding the processing associated with record locking calls to the lock manager 7 10 File Sharing and Buffering File Sharing and Buffering 7 2 Record Locking In previous releases to OpenVMS Version 7 2 1H1 if a file is opened allowing write sharing an exclusive record lock is taken out for all record operations both read and write Applications may obtain record locking modes other than the exclusive lock default by specifying certain options to the RAB L_ROP field However all the options involve some level of record locking That is the options require ENQ or DEQ system service calls to the lock manager The user record locking options include the RAB V NLK no lock
210. concatenation within the same file specification occurs only with a rooted device logical name Normal directory concatenation occurs only through the application of defaults Rooted directory concatenation can occur within the same file specification and through the application of defaults Rooted device logical names specify a device name and a root directory RMS translates a rooted device logical name into the device and root directory before it merges any other parts of a file specification if present into the equivalence file specification When you use a rooted device logical name together with a directory specification the following rules apply You can refer to the root directory itself The syntax of 000000 and relative directory references refer to the root directory You can never refer to a directory above the specified root directory because the root directory is the logical MFD whenever a directory specification is used When the process default directory is the root directory a reference to results in an error as shown in the following example DEFINE TRANSLATION ATTR CONCEALED BASE DUA7 ROOT1 SET DEFAULT BASE 000000 DIRECTORY DIR The system responds to this command sequence with the following display BASE 000000 No files found The user then tries to check the contents of the next higher directory with the following command DIRECTORY DIR The system responds with the following messages
211. cord The Update service is allowed only on disk devices The remainder of this section briefly describes the record retrieval Find and Get services the record insertion Put service the record modification Update service and the record deletion Delete service Note that all references to services imply applicability to similar functional capabilities found in high level languages 8 2 1 Locating and Retrieving Records You can use the Find and Get services to locate and retrieve a record The Find service locates a record and establishes its location as the current record position in a record stream but does not return the record to a buffer The Get service locates the record establishes its location as the current record position in the record stream and returns it to the buffer area you specify If you use the Get service you must allocate a buffer area in the data portion of your program to store the retrieved record by defining an appropriate variable or multivariable record structure in the program Note When you invoke the Get service RMS takes control of the record buffer and may modify it RMS returns the record size but it can guarantee record integrity only from the access point to the end of the record 8 2 Record Processing Record Processing 8 2 Primary Services In addition to retrieving the record RMS returns to your program the length of the record in control block field RAB W RSZ record siz
212. cords are usually inserted at the end of the file To insert records randomly within the current boundaries of the file at a relative record number less than or equal to the highest record number set the update if option FDL attribute CONNECT UPDATE IF RAB L_ROP bit RAB V UIF to overwrite existing records When accessing a sequential file randomly by relative record number your program must provide the record number at symbolic offset RAB L_KBF and must specify a key length of 4 at symbolic offset RAB B KSZ in the RAB Record Processing 8 7 Record Processing 8 4 Record Access for the Various File Organizations 8 4 2 Processing Relative Files The relative file organization permits greater program flexibility in performing record operations than the sequential organization A program can read existing records from the file using sequential random access by relative record number mode or random access by RFA mode You can write new records either sequentially or randomly as long as the intended record location cell does not already contain a record You can also delete records All record access modes for relative files allow you to establish the current record position using the Find or Get service After finding the record RMS permits you to delete the record from the relative file After the record is deleted the empty cell becomes available for a new record In addition your program can update records anywhere in the file For
213. cter set and the ASCII a characters that can be used in a quoted string for naming ANSI formatted magnetic tape files 5 2 3 On Disk Components The following sections describe the file specification components that apply to files residing on disks The details of the components are determined by whether the application is running on an Alpha system or a VAX system and on the structure level of the disk 5 2 3 1 Character Set for On Disk Components As of OpenVMS V7 2 on Alpha systems RMS supports a larger character set than was supported in previous versions it is also larger than the set that is supported under V7 2 on VAX systems Creating such files is supported only on disks of ODS 5 or greater structure level 5 2 3 1 1 Base Character Set On OpenVMS Alpha and VAX systems on ODS 5 and ODS 2 devices a basic set of simple characters is valid for the node device root directory and file name and type components of a file specification These characters include the following e Upper and lowercase alphanumeric characters A 2Z a 2 0 9 e Special ASCII 7 bit characters b 5 2 3 1 2 Extended Character Set In addition OpenVMS V7 2 on Alpha systems and ODS 5 disks includes support for the use of file names and subdirectory and root subdirectory names that include all possible 8 bit characters excluding values 00 through 1F hexadecimal and excluding the following characters coef eee OpenVMS 7 3 1 on Alpha
214. cteristics 4 1 2 1 Using the Edit FDL Utility You can use the Edit FDL utility in two ways with a terminal dialog interactively or without one noninteractively If you use the Edit FDL utility noninteractively you can execute only the OPTIMIZE script The OPTIMIZE script lets you optimize an existing FDL file without an interactive session For more information see Section 10 3 Alternatively if you use the Edit FDL utility interactively you can use all the scripts each of which has a series of menus When you invoke the Edit FDL utility it displays a main menu To select a menu item you only need to enter the first letter of the item because each selection has a unique first letter Table 4 1 summarizes the Edit FDL utility commands Table 4 1 Summary of the Edit FDL Utility Commands Command Function ADD Inserts one or more lines into the FDL definition If the line already exists you can replace it with your new line Once you have inserted a line you can continue to add lines until you are satisfied with that particular primary section If no primary section exists to hold the secondary attribute being added the Edit FDL utility creates one DELETE Removes one or more lines from the FDL definition If you delete all of the secondary attributes in a primary section you effectively remove the primary attribute Once you have removed a line you can continue to delete lines under that particular primary section
215. cument discussions that refer to OpenVMS Cluster environments apply to systems that include only VAX nodes and OpenVMS Cluster systems that include at least one Alpha node unless indicated otherwise Processing in an OpenVMS Cluster environment offers many advantages e Performance In general the performance of each node in an OpenVMS Cluster is similar to that of a single node system that has the same processing load assuming the aggregate I O per disk drive is reasonable e Availability With the appropriate configuration a node that leaves the OpenVMS Cluster does not stop the OpenVMS Cluster e Flexibility You can process shared applications on more than one node e Accessibility Shared resources are very easy to use in an OpenVMS Cluster The synchronized access to the data provides data integrity with no redundancy For more information about OpenVMS Clusters see OpenVMS Cluster Systems 3 7 1 OpenVMS Cluster Shared Access Shared access is one of the chief advantages of processing in an OpenVMS Cluster environment Many applications that run on a single node system can run on an OpenVMS Cluster with no changes However applications that access shared files in an OpenVMS Cluster incur some additional overhead for the OpenVMS Cluster synchronization the amount of additional overhead depends on the locking requirements of your application 3 32 Performance Considerations Performance Considerations 3 7 Process
216. d connect options that may affect performance Option Description Asynchronous record Specifies that record I O for this record stream is done processing asynchronously See Section 8 7 e FDL CONNECT ASYNCHRONOUS e RMS RAB L_ROP RAB V ASY Deferred write Allows records to be accumulated in a buffer and written only when the buffer is needed or when the file is closed For use by all except nonshared sequential files See Chapter 3 e FDL FILE DEFERRED WRITE e RMS FAB L_FOP FAB V DFW Default extension Specifies the number of blocks to be allocated to a file when more quantity space is needed e FDL FILE EXTENSION e RMS FABSW_DEQ lIndicates an option that can be specified for each record processing operation For more information see Section 9 3 9 8 Run Time Options Run Time Options 9 2 Options Related to Opening and Closing Files Option Description Fast delete Global buffer count Locate mode Multiblock count Number of buffers Read ahead Retrieval window size Postpones certain internal operations associated with deleting indexed file records until the record is accessed again This allows records to be deleted rapidly but may affect the performance of subsequent accessors reading the file e FDL CONNECT FAST DELETE e RMS RAB L ROP RAB V FDL Specifies whether global buffers are used and the number to be used if the record stream is the first to connect to the file S
217. d is automatically granted to certain user categories when UIC based protection is evaluated CONTROL access grants the accessor all the privileges of the object s actual owner For more information see the documentation related to OpenVMS security 4 4 2 ACL Based Protection You can also protect disk files with access control lists ACLs ACLs cannot be used with magnetic tape files An ACL is a list of people or groups who are allowed to access a particular file ACLs offer more scope than UICs in determining what action you want taken when someone tries to access your file You can provide an ACL on any file to permit as much or as little access as you want You can specify the ACL for a file when you create it if you use RMS directly You cannot specify an ACL in an FDL specification and ACLs are not supported over DECnet 4 26 Creating and Populating Files Creating and Populating Files 4 4 Defining File Protection After a file is created you can define the access control list for it with the ACL Editor You can invoke this editor with either of the following DCL commands e EDIT ACL e SET FILE ACL For more information about how to invoke modify and display ACLs see the OpenVMS System Management Utilities Reference Manual For additional information about operating system security features see your system or security manager or consult the documentation related to OpenVMS security 4 5 Populating a File The
218. d to the 2 digit year value if an ASCII zero is indicated it is assumed that 2000 is added to the 2 digit year value For the YYDDD part of the format only dates are relevant for these fields time is always returned as 00 00 00 00 OpenVMS Version 5 1 1 and later versions implement the ASCII zero to the previously existing ASCII space per the ANSI X3 27 1987 standard making them year 2000 ready This ANSI standard is believed to be valid through the year 2100 OpenVMS versions prior to Version 5 1 1 have known problems initializing and mounting magnetic tapes in the year 2000 and later 1 30 Introduction Introduction 1 3 Magnetic Tape Concepts By default the current date is written to both the creation and expiration date fields when you create a file Because the expiration date is the same as the creation date the file expires on creation and you can overwrite it immediately If the expiration date is a date that is later than the creation date and if the files you want to overwrite have not expired you must specify the OVERRIDE EXPIRATION qualifier with the INITIALIZE or MOUNT command To write dates other than the defaults in the date fields in this label specify the creation date field CDT and the expiration date field EDT of the RMS date and time extended attribute block XABDAT When you do not specify a creation date RMS defaults the current date to the creation date field To specify a zero creation date you mu
219. d trailing characters are compressed With front key compression any characters that are identical to the characters at the front of the previous key are compressed For example the keys JOHN JOHNS JOHNSON and JONES appear as JOHN S ON and NES With rear key compression any repeating characters at the end of the key are compressed to a single character For instance the key JOHNSON O0000 appears as JOHNSONO Enabling index compression results in RMS doing a sequential search in index buckets rather than its default binary search since each index key value must be expanded until a match is found With data compression RMS can compress sequences of up to 255 repeating characters in the data portion of the user data records For optimal performance RMS does not compress sequences having less than five repeating characters Compression has a direct effect on CPU time and disk space Compression increases CPU time but the keys are smaller so your application can scan more quickly through the data and index buckets Performance Considerations 3 19 Performance Considerations 3 5 Tuning an Indexed File The disk space saved by using Prolog 3 indexed files can significantly improve performance With compression each I O buffer can hold more information to improve buffer space efficiency Compression can also decrease the number of index levels which decreases the number of I O operations per random access Prolog 3 files can have
220. default file specification or the related file specification The program supplied file specifications can be specified using the methods summarized in the following chart File Specification How You Can Specify It Primary Use the FDL attribute FILE NAME use the file name or the name following the FILE FILE ID or FILENAME keywords in the OPEN statement in some high level languages or use the string pointed to by the FAB field FAB L FNA Default Use the FDL attribute FILE DEFAULT NAME use the default file specification or the name following the DEFAULTNAME or DEFAULT FILE ID keyword in the OPEN statement in some high level languages or use the string pointed to by the FAB field FAB L DNA Advanced Use of File Specifications 6 3 Advanced Use of File Specifications 6 1 How RMS Applies Defaults File Specification How You Can Specify It Related Use the name block NAM pointed to by the NAM L RLF field the related name block must specify the location of a file specification which must be pointed to by the NAM field NAM L RSA Specifying all components in the primary file specification explicitly decreases the chance of error However defaults are provided and can be very useful especially for general purpose applications and for applications in which the file specification is entered by the interactive user Another option to consider is the use of logical names See the appropriate languages documentation f
221. default file specification to be used to fill any missing components not provided by the primary file specification After applying these defaults if any components are still missing additional defaults are applied e FDL FILE DEFAULT NAME e RMS FAB L DNA and FAB B_DNS Related Specifies a related file specification that is used to provide additional defaults when a related file is used If the device or directory components are missing RMS provides default values from the process default device SYS DISK and the current process default directory e FDL None e RMS FAB L_NAM and NAM L_RLF 9 2 3 File Performance Options A number of run time options that open files and connect record streams can collectively improve application performance Such options include the buffering options discussed in Chapter 7 Two run time performance options not discussed previously are particularly important when adding records to a file extension size and window size 9 2 3 1 Extension Size If you intend to add records to the file specify a reasonable default extension size to reduce the number of times the file is extended Use the Edit FDL utility to calculate the correct extension size The Edit FDL utility uses your responses to assign an optimum value for the FDL attribute FILE EXTENSION With multiple area files the Edit FDL utility assigns optimum values to the AREA EXTENSION attributes If you do not specify an extension size R
222. der is already in use e File headers The largest part of the index file is made up of file headers Each file on the volume has a file header which describes such properties of the file as file ownership creation date and time Each file header also contains a list of the extents that define the physical location of the file When a file has many extents it may be necessary to have multiple file headers for locating them When this occurs each header is assigned a file identifier number to associate it with the appropriate file When you create a file you normally specify a name that RMS assigns to the file on a Files 11 ODS volume RMS places the file name and file identifier associated with the newly created file in a directory that contains an entry defining the location for each file To subsequently access the file you specify its name The system uses the name to define a path through the directory entry to the file identifier In turn the file identifier points to the file header that lists the file s extents 1 2 2 2 Storage Bit Map File The storage bit map file controls the available space on a volume this file is listed in the master file directory as BITMAP SYS 1 It contains a storage control block which consists of summary information intended to optimize the Files 11 space allocation and the bit map itself which lists the availability of individual blocks Introduction 1 9 Introduction 1 2 Disk Concepts 1 2
223. directory names and file names Device names and node names must conform to ODS 2 requirements 5 2 4 3 Uppercase and Lowercase Letters and Multiple File Versions On ODS 5 disks on Alpha systems the Extended File Specifications changes added support in OpenVMS Version 7 2 for preserving case as in uppercase and lowercase letters If a file is created with lowercase letters from program control the name as stored on disk is lowercase From the DCL command interface file names that are entered at the command prompt with lowercase letters will be translated by default to uppercase before they are passed to RMS Case may be preserved from the DCL command interface by using the DCL command SET PROCESS PARSE STYLE EXTENDED also see the SYS SET PROCESS PROPERTIESW system service File look ups however are case blind For example the filename File Txt as stored on an ODS 5 disk could be accessed with a reference to FILE TXT or file txt As of OpenVMS Version 7 3 1 an option may be set for file look ups at either the process or file level to request RMS to either ignore or notice the case sensitivity of file names on ODS 5 disks At the process level the user may request RMS to ignore case by using SET PROCESS CASE LOOKUP BLIND If a file on an ODS 5 disk already exists whose name matches that of a file being created except for its case the new file will be created with the same case as the existing file rather than with the case
224. directory specifications including directory syntax conventions see Section 6 3 One File Specification to Locate Many Files Five services can translate and apply defaults to a file specification to produce a fully qualified file specification the Create Open Erase Parse and Rename services Other file services must be preceded by one of these services to parse the file specification and in some cases to open the file If a file specification contains one or more wildcard characters it must be preprocessed using the Parse and Search services before the file can be located The Parse service sets bit values in the name block file name status bits field NAM L FNB or NAML L FNB This field can be tested to determine whether a wildcard character or a search list logical name is present The Search service locates a file and specifies its name without wildcard characters If wildcard characters are present you must first invoke the Search service before processing opening or creating the file if wildcard characters are not present the file can be processed without invoking the Search service To process a single file you need to invoke the Search service only once to process many files invoke the Search service as many times as needed to return the next full file specification When no more files match the file specification the Search service returns a no more files found message RMS NMF In summary the Parse and Search ser
225. disk In locate mode RMS allows the application program to access records in an I O buffer by providing the address of the returned record as the internal buffer location instead of an application program buffer location field RAB L RBF Usually this reduces program overhead because records can be processed directly within the I O buffer Locate mode is only available for input operations Because it may not always be possible to use locate mode you must supply an application program buffer for cases in which move mode must be used even though you specify locate mode see the OpenVMS Record Management Services Reference Manual Other RMS facilities allow programs to control I O buffer space allocation or to leave space management to RMS The following sections describe buffering 7 3 2 Understanding Buffering Your program perceives RMS record processing as the movement of records between a file and the program itself In fact RMS uses internal memory areas called I O buffers to read or write blocks or buckets of data Transparent to your program RMS transfers blocks or buckets of a file into or from an I O buffer Records within the I O buffer are then made available to the program when RMS transfers the records between the I O buffer and the application program s record buffer The unit of data transfer between a file and the I O buffers depends on the file organization For the sequential organization RMS reads and writes a block or
226. does not recommend that you modify an existing file using block I O if the file is also to be accessed by record level operations Block I O does not update any internal record information The block I O facility however does allow you to create your own file organizations This file structure must be maintained through specialized user written programs and procedures RMS cannot access these structures with its record access modes For more information about using block I O see the OpenVMS Record Management Services Reference Manual 8 6 Current Record Context For each RAB connected to a FAB RMS maintains current context information about the record stream including the current record position and the next record position Furthermore the current context is different for the various services as shown in Table 8 3 The current record context is internal to RMS you have no direct contact with it However you should know the context for each service in order to properly access records when you invoke a service Table 8 3 Record Access Stream Context Service Access Mode Current Next Connect Not applicable None First record Connect with RAB L_ROP Not applicable None End of file RAB V_EOF bit set Get when last service Sequential Old next New current was not a Find record record 1 Get when last service Sequential Unchanged Current was a Find record 1 Get Random New New current record 1 Put sequential file Sequential None E
227. e and the file address of the record in control block field RAB L_RBF record buffer If you direct RMS only to locate the record it does not write the record into your buffer Instead it sets the RAB W RSZ and RAB L_RBF fields to point to an internal buffer where the record is located When using indexed files you may need to allocate a buffer for the desired key and to specify its length When using high level languages the language s compiler may automatically handle the allocation and size specification of the record buffer and the key buffer In some applications you can minimize record I O and improve performance by using the Find service instead of the Get service For example a process does not have to retrieve a record when it is preparing to invoke the Update Delete Release or Truncate service If a process intends to update a record that is accessible to other processes it should lock the record until it completes the update For interactive applications where the user verifies that the appropriate record is being accessed before deleting it or updating it the program should use the Get service instead of the Find service In some situations a process may use two services and two types of record access to retrieve a set of records For example the process might use the Find service and random access mode to locate the first record in the set and then switch to the Get service for sequentially retrieving the records in t
228. e successive records must be in the specified sort order by primary key 8 4 3 2 Random Access One of the most useful features of indexed files is that you can randomly retrieve records by the record s key value A key value and a key of reference such as a primary key first alternate key and so forth can be specified as input to the record processing service RMS searches the specified index to locate the record with the specified key value When reading records in random access by key mode your program may specify one of four types of key matches e Exact key match e Approximate key match e Generic key match e Approximate and generic key match Exact match requires that the record s key value precisely match the key value specified by the program s Get service Approximate key match allows the program to select one of the following options e Equal or next key option e Next key option e Reverse equal or next key option e Reverse next key option The advantage of using an approximate key match is that your program can retrieve a record without knowing its precise key value RMS uses the approximations in your program to return the record with the key value nearest the specified value If you elect to use a generic key match your program need provide only a specified number of leading characters in the key for example the first 5 bytes characters of a 10 byte string data type key 8 12 Record Processing Rec
229. e Edit FDL utility The Glossary provides definitions of terms that are commonly used in this guide xiii Associated Documents The reader should be familiar with the information in the following documents e The OpenVMS User s Manual describes the use of the operating system for a general audience e Programmers should be familiar with the appropriate documentation for the high level language in which the application will be written e System managers should be familiar with the OpenVMS System Manager s Manual a task oriented guide to managing an OpenVMS system Related Documents For additional information about Compaq OpenVMS products and services access the Compaq website at the following location http www openvms compaq com Reader s Comments Compaq welcomes your comments on this manual Please send comments to either of the following addresses Internet openvmsdoc compaq com Mail Compaq Computer Corporation OSSG Documentation Group ZKO3 4 U08 110 Spit Brook Rd Nashua NH 03062 2698 How To Order Additional Documentation Visit the following World Wide Web address for information about how to order additional documentation http www openvms compaq com Conventions In this manual every use of DECwindows and DECwindows Motif refers to DECwindows Motif for OpenVMS software The following conventions are also used in this manual Ctrl x A sequence such as Ctrl x indicates that you must hold down t
230. e also placed in buckets The last index record in a bucket itself has the high key value for its bucket this high key value is then copied to an index record on the next higher level This process continues until all of the index records on a level fit into one bucket This level is then known as the root level for that index structure Figure 3 1 is a diagram of an index structure Figure 3 2 illustrates a primary index structure For simplicity the records are assumed to be uncompressed and the contents of the data records are not shown The records are 132 bytes long including overhead with a primary key field of 6 bytes Bucket size is one block which means that each bucket on Level 0 can contain three records You calculate the number of records per bucket as shown by the following algorithm Block Size Bytes of Overhead R ds Per Bucket Record Size Including Overhead aerae Substituting the values in this instance 512 15 132 3 77 3 20 Performance Considerations Performance Considerations 3 5 Tuning an Indexed File Note that you must round the result down to the next lower integer in this case the integer 3 Figure 3 1 RMS Index Structure Level 2 PI tt JS ZANAN INN Y YUY WY Y UY ZK 0734 GE PSS t2 ff Q eo Because the key size is small and the database in this example consists of only 27 records the index records can all fit in one bucket on level
231. e always written after the trailer labels of the last file on a volume Tape Mark Indicates tape that is blank or that has not yet been Scratch Tape overwritten Scratch tape can exist between the logical end of volume and the EOT marker End of Tape er Marker EOT Marks beginning of the end of the writable area al EOV1 EOV2 EOV3 ZK 0981 GE Introduction 1 21 Introduction 1 3 Magnetic Tape Concepts Beginning of Tape and End of Tape Markers Every volume has beginning of tape BOT and end of tape EOT markers These markers are pieces of photoreflective tape that delimit the writable area on a volume ANSI magnetic tape standards require that a minimum of 14 feet to a maximum of 18 feet of magnetic tape precede the BOT marker a minimum of 25 feet to a maximum of 30 feet of magnetic tape of which 10 feet must be writable must follow the EOT marker The EOT marker indicates the start of the end of the writable area of the tape rather than the physical end of the tape Therefore data and labels can be written after the EOT marker Tape Marks Tape marks separate the file labels from the file sections separate one file from another and denote the logical end of volume On the basis of the number and relative placement of tape marks written on a volume OpenVMS systems determine whether a tape mark delimits a label a file or a volume Tape marks are written both singly and in pairs Single tape marks separate ei
232. e contents of the global buffer are copied to a process local buffer before other processes are allowed to access the global buffer contents Subsequent use of the modified buffer by the process that deferred the writeback refer to the process local buffer while it remains in the process local cache 3 12 Performance Considerations Performance Considerations 3 2 Tuning Reference to the global buffer by another process causes the contents of the process local buffer to be written back to disk If a global buffer is modified and the deferred write option is not enabled then the contents are written out to disk from the global buffer Therefore using global buffers along with the deferred write option may cause a slight increase in processing overhead if in fact no further references to the modified buffer occur before it is flushed from the cache anyway For that reason you may want to disable the deferred write option for processes that do not reaccess buffers after records have been written to them Section 3 3 Section 3 4 and Section 3 5 discuss the use of global buffers in tuning the various file types 3 2 2 4 Read Ahead and Write Behind Processing The operation of sequentially organized files can be improved by implementing read ahead and write behind processing These features improve performance by permitting record processing and I O operation to occur simultaneously The read ahead and write behind features are default run time a
233. e data buckets are reclaimed the pointers to them in the index buckets are deleted If as a result any of the index buckets become empty they too are reclaimed Note that RFA access is retained after bucket reclamation The only effect that CONVERT RECLAIM has on a Prolog 3 indexed file is that empty buckets are reclaimed To use CONVERT RECLAIM use the following command syntax in which filespec specifies a Prolog 3 indexed file CONVERT RECLAIM filespec Please note that the file cannot be open for shared access at the time that you give the CONVERT RECLAIM command 10 5 Reorganizing a File Using the Convert utility is the easiest way to reorganize a file In addition CONVERT cleans up split buckets in indexed files Also because the file is completely reorganized buckets in which all the records were deleted will disappear Note that this is not the same as bucket reclamation With CONVERT the file becomes a new file and records receive new RFAs To use the Convert utility to reorganize a file use the following command syntax CONVERT input filespec output filespec If you do not want to rename the file use the same name for input filespec and output filespec 10 28 Maintaining Files Maintaining Files 10 6 Making Archive Copies 10 6 Making Archive Copies Another part of maintaining files is making sure that you protect the data in them You should keep duplicates of your files in another place in case something happ
234. e following form node device root directory name filename type version Locating and Naming Files on Disks 5 1 Locating and Naming Files on Disks 5 1 Understanding Disk File Specifications The following table lists the characters that separate components of a file specification Component Separator Character s Node Double colon ends a node name Device Single colon ends a device name Root Square brackets or angle brackets lt gt delimit the root name Within the root component a period separates subdirectory names A period before the closing bracket distinguishes a root component from a directory Directory Square brackets or angle brackets lt gt delimit the directory name Within the directory component a period separates subdirectory names File Name The rightmost period that is not the version delimiter begins the type component and ends the file name File Type The rightmost period that is not the version delimiter begins the type component A version delimiter ends the type component File Version Period or semicolon followed by legal version characters begins the version Section 5 2 7 describes a legal version component The end of the file specification ends the file version Some examples of valid file specifications follow DISK1 MYROOT MYDIR FILE DAT DISK1 MYDIR FILE DAT MYDIR FILE DAT FILE DAT 10 NODE DISK5 REMOTE ACCESS
235. e logical names SRC and DST You must define the logical name for the process before you run the program using the following sequence of commands DEFINE SRC TRNTO USER STOCKROOM PAPER INVENTORY DAT DEFINE DST BOSTON LPAO RUN TRANSFER In Example 5 1 standard I O calls transfer the files records from one device to another Note the use of the OpenVMS file specification format with a remote node name If the remote node is running a system other than OpenVMS the format of the file specification may differ After opening the files and copying all the records the program closes the channels thereby terminating network operations These operations are similar for applications in the other high level languages 5 18 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 6 Sample Use of Logical Names Example 5 1 Using Logical Names for Remote File Access PROGRAM TRANSFER C C This program creates a sequential file with variable length C records from a sequential input file The input and output C files are identified by the logical names SRC and DST C respectively C CHARACTER BUFFER 132 C 100 FORMAT 0 A 200 FORMAT A C C Open the input and output files C OPEN UNIT 1 NAME SRC TYPE OLD ACCESS SEQUENTIAL 1 FORM FORMATTED OPEN UNIT 2 NAME DST TYPE NEW ACCESS SEQUENTIAL 1 FORM FORMATTED CARRIAGECONTROL LIST 2 RECORDTYPE VARIABLE C C Transfer records
236. e name is not present RMS processes the related file specification as an output file specification as shown in the following table File Specification Null Field Wildcard Field Component Specification Specification Node Remains null Illegal Device Remains null Illegal Directory Remains null Substitute from related file specification with restrictions Filename Use related file Substitute from related Specification file specification Type Use related file Substitute from related specification file specification Version Remains null Substitute from related file specification When the FAB V_OFP bit is set and a node name is present RMS processes the related file specification as an output file specification as shown in the following table File Specification Null Field Wildcard Field Component Specification Specification Device Remains null Illegal Directory Remains null Substitute from related file specification with restrictions Filename Use related file Substitute from related specification file specification Type Use related file Substitute from related specification file specification Version Remains null Substitute from related file specification As shown in the previous table a wildcard character in an output directory specification is subject to the following syntax restrictions e Only the asterisk and the ellipsis are permitted in the output directory specification In
237. e node system However these locks are used when you open and close files so the time for lock operations is only a fraction of the total time needed to open and close files There is no performance difference between a single node system and an OpenVMS Cluster if the file sharing takes place on a single node of the OpenVMS Cluster Only when sharing spans across the OpenVMS Cluster nodes does distributed locking occur As a result the record locking itself may take a little longer but because you have multiple CPUs in the OpenVMS Cluster your application benefits from the added processing power Sharing files in an OpenVMS Cluster also requires enough memory for nonpaged pool to store additional lock data structures This requirement however is dependent upon your processing load 3 7 1 2 I O Considerations Sharing files in an OpenVMS Cluster environment also means sharing resources such as disks and other pieces of I O hardware When applications on many nodes share data on one disk OpenVMS Cluster performance may degrade due to excessive I O operations 3 7 2 Performance Recommendations Four general recommendations about performance in an OpenVMS Cluster environment are described in the following list e Estimate the I O needs of your application In an OpenVMS Cluster and particularly with a shared file multiple nodes can generate many I O requests to a single disk The capacity of the disk to handle I O traffic can affec
238. e specified only for volumes that must be transportable to RSX 11M RSX 11D RSX 11M PLUS and IAS systems as these systems support only that structure level Additionally you may be required to handle structure level 1 volumes transported to OpenVMS systems from one of the previously mentioned systems Structure level 1 volumes have the following limitations e Directories No hierarchies of directories and subdirectories and no ordering of directory entries that is the file names in any way RSX 11M RSX 11D RSX 11M PLUS and IAS systems do not support subdirectories and alphabetical directory entries e Disk quotas Not supported e Multivolume files and volume sets Not supported e Placement control Not supported e Caches No caching of file header blocks file identification slots or extent entries e System disk Cannot be a structure level 1 volume e OpenVMS Cluster access Local access only cannot be shared across an OpenVMS Cluster Note In this document discussions that refer to OpenVMS Cluster environments apply to both VAXcluster systems that include only VAX nodes and OpenVMS Cluster systems that include at least one Alpha node unless indicated otherwise e Clustered allocation Not supported e Backup home block Not supported e Protection code E Means extend for the RSX 11M operating system but is ignored by OpenVMS systems e File versions Limited to 32 7
239. e version does not exceed 255 simple characters ODS 5 disks support file names for which the sum of the lengths of the file name and the file type does not exceed 236 bytes Be careful when naming files that will be copied or accessed by remote systems File name restrictions are generally determined by the file naming capabilities of the networked systems that require access to them These restrictions must be considered part of the overall application design when network access is required 5 4 3 Maximum Subdirectory Depths RMS supports creating and accessing up to 255 subdirectory levels in any combination in the root and directory components on ODS 2 and ODS 5 volumes accessed from Alpha systems For ODS 2 and ODS 5 volumes accessed from VAX systems RMS supports up to 8 subdirectory levels each for the root and directory components Locating and Naming Files on Disks 5 13 Locating and Naming Files on Disks 5 4 File Specification and Component Length Limits 5 4 4 Accessing Files on ODS 5 Disks from VAX Systems On VAX systems RMS allows access to ODS 5 volumes But file specifications are allowed on those volumes that RMS on VAX does not support Some of the limitations are described here When a search is done of a directory that contains files whose names are legal for ODS 5 but not for ODS 2 one of two pseudonames V PISO LATIN or PUNICODE will be displayed Such files can be accessed via RMS only from an
240. ecord Management Services record stream The access environment for reading writing deleting and updating records relative file organization The arrangement of records in a file in which each record occupies a cell of equal length within a bucket Each cell is assigned a successive number called a relative record number which represents the cell s position relative to the beginning of the file relative record number An identification number used to specify the position of a record cell relative to the beginning of the file used as the key during random access by key mode to relative files reorganization A record by record copy of an indexed file to another indexed file with the same key attributes as the input file RFA See record file address RMS Record Management Services The file and record access subsystem of the operating system RMS helps your application program process records within files thereby allowing interaction between your application program and the data RMS 11 A set of routines that is linked with compatibility mode and PDP 11 programs and provides similar features for RMS The file organizations and record formats used by RMS 11 are very similar to those of RMS one exception is that RMS 11 does not support Prolog 3 indexed files which are supported by RMS root bucket The primary routing bucket for an index geometrically the top of the index tree When a key search begins RMS goes first t
241. ee Section 7 3 e FDL CONNECT GLOBAL BUFFER COUNT e RMS FABSW GBC Allows the use of locate mode not move mode when reading records See Section 7 3 e FDL CONNECT LOCATE MODE e RMS RAB L ROP RAB V LOC Allows multiple blocks to be transferred into memory during a single I O operation for sequential files only See Chapter 3 and Section 7 3 e FDL CONNECT MULTIBLOCK COUNT e RMS RAB B MBC Enables the use of multiple buffers for the buffer cache when used with indexed and relative files when used with sequential files enables the use of multiple buffers for the read ahead and write behind options See Section 7 3 e FDL CONNECT MULTIBUFFER COUNT e RMS RAB B MBF Alternates buffer use between two buffers when reading sequential files See Chapter 2 e FDL CONNECT READ AHEAD e RMS RAB L_ROP RAB V RAH Specifies the number of entries in memory for retrieval windows which corresponds to the number of extents for a file e FDL FILE WINDOW_SIZE e RMS FAB B_RTV Indicates an option that can be specified for each record processing operation For more information see Section 9 3 Run Time Options 9 9 Run Time Options 9 2 Options Related to Opening and Closing Files Option Description Sequential access Indicates that a sequential file may only be accessed sequentially only e FDL FILE SEQUENTIAL ONLY e RMS FAB L_FOP FAB V_SQO Write behind Alternates buffer use between two buffers when writ
242. efault node names specifies the local node this form 5 2 1 2 Remote Node The following file specification formats are used for accessing files on remote nodes node filespec node access control string filespec The second file specification format includes an access control string If an access control string is specified or if the process seeking to gain access to a remote file has a proxy login account on the remote node the specified remote process uses its access rights to locate the file If an access control string is not specified and a proxy account does not exist on the remote system the local process may use the default DECnet account if there is one to locate the file The following file specification format known as a foreign file specification is used to locate files on remote nodes that might have file specification formats that differ from those of the local node node foreign filespec The only action RMS takes with the foreign file specification is to translate the logical node name if applicable This format is especially useful when the remote system is not an OpenVMS system and the file specification does not conform to OpenVMS file specification syntax conventions Refer to the DECnet for OpenVMS Networking Manual for more information The following file specification format does not specify a file directly Instead it specifies a task on the remote system node task spec string For more
243. efining symbols to USEROPEN routine 5 23 DELETE attribute 7 3 DELETE command 10 25 Delete service 8 2 8 4 high level language equivalents 8 2 run time options 9 21 Design graphics mode 4 11 Design mnemonic 4 13 Device component 5 3 DID abbreviated directories 6 19 Direct access mode 1 2 Directories 6 11 DIRECTORY FULL command for checking RMS statistics status 3 29 Directory component 5 8 Directory specifications normal 6 11 to 6 13 rooted 6 14 to 6 18 Directory trees 6 12 DIRECTORY ENTRY attribute 4 32 Disconnect service 8 5 Disks See also CD ROM basic concepts 1 3 Disk structure Files 11 1 8 Double tape mark 1 22 Index 3 DOWN command 10 11 10 12 Dual format ISO 9660 CD and Files 11 CD 1 4 DUMP command 10 11 Duplicate keys null key processing 3 22 E EDIT ACL command 4 27 Edit FDL utility EDIT FDL 1 39 calculating bucket size 3 16 3 26 calculating extension size 9 7 commands 4 3 contiguous files 3 4 creating areas for index structures 3 24 creating FDL files 4 2 4 5 default value 4 11 invoking a script 4 4 optimization algorithms A 1 Optimize script 10 1 10 22 prompt 4 10 specifying run time options 9 1 to 9 5 Empty fixed length file cells effect on sequential search of relative files 2 3 End of tape markers See EOT markers EOF end of file label 1 22 EOT markers 1 22 EOV end of volume label 1 22 Equal or n
244. either by using the FDL attribute FILE ALLOCATION or by using the file access control block field FAB L_ALQ 3 2 1 2 Contiguity Use the FILE secondary attribute CONTIGUOUS to arrange the file contiguously on the disk if you have sufficient space If you assign the CONTIGUOUS attribute and there is not enough contiguous space on the disk RMS does not create the file To avoid this consider using the FDL attribute BEST TRY CONTIGUOUS instead of the CONTIGUOUS attribute The BEST TRY CONTIGUOUS attribute arranges the file contiguously on the disk if there is sufficient space or noncontiguously if the space is not available for a contiguous file You can make this choice by accepting the FDL default values for both attributes NO for CONTIGUOUS YES for BEST TRY CONTIGUOUS or by taking the RMS FAB V_CBT option in the FAB L_FOP field 3 2 1 3 Extending a File An extend operation file extend adds unused disk blocks to an RMS file when the free space within a file is exhausted If the unused disk blocks are not contiguous to the previously allocated disk blocks of the file the file becomes fragmented As a file becomes fragmented access time increases and processing performance can degrade Appropriate use of extend operations can minimize file fragmentation If you intend to add large amounts of data to a file over a short time using large extends will minimize file fragmentation and the overhead of extend operations Conversely if you
245. elds each identified by a symbolic offset value For instance the allocation quantity for a file is specified in a longword length field having a symbolic offset value of FAB L ALQ FAB L ALQ indicates the number of bytes from the beginning of the FAB to the start of the field To exchange record related information with RMS you use a control block called a record access block RAB You use the RAB to define the location type and size of the input and output buffers the record access mode certain tuning options and other information The symbolic offset values for the RAB fields have the prefix RAB to differentiate them from the values used to identify FAB fields The RAB symbolic offset values have the same general format where the letter following the dollar sign indicates the field length and the letters following the underscore are a mnemonic for the field s function For example the multibuffer count field MBF specifies the number of local buffers to be used for I O and has the symbolic offset value RAB B_MBF The value of RAB B MBF is equal to the number of bytes from the beginning of the RAB to the start of the field Where applicable RMS uses control blocks called extended attribute blocks XABs together with FABs and RABs to support the exchange of information with RMS For example a Key Definition XAB specifies the characteristics for each key within an indexed file The symbolic offset values for XAB fields have the common
246. elect the wait if locked option and the requesting service must wait to access the record it returns an alternate success status that indicates that it had to wait RMS OK WAT 7 2 3 3 Reading Regardless of Lock The third choice available to you for handling record locking conflicts involves using the read regardless of lock option This option allows the accessing service to ignore a lock that prohibits read access If a lock is granted under the specified record locking option access is granted and the service returns with the specified lock If the lock is denied the read regardless option allows the accessing service Get or Find to read the record regardless of the lock The service returns without a lock for all three file organizations but the returned status depends on the file organization e For sequential files the service returns RMS SUC e For relative and indexed files the service returns alternate success status RMS OK RRL An application program might use the read regardless option to avoid record locking conflicts when a coordinated view of a record is not necessary This option can also be used to continue sequential reads through a locked record Note that when you use the read regardless option with the wait if locked option and a wait timeout period RMS acts on the read regardless option only after the wait timeout expires 7 2 4 Miscellaneous Record Locking Options This section describes two miscella
247. eliminating the need for instance to specify the device specification for each file specification when all the files are located on the same device The related file specification provides defaults when a related file name block is present To use the related file specification the file access block must specify the address of the primary file s name block in the FAB L_NAM or FAB L_ NAML field and that name block must specify the address of the related file s name block in the NAM L_RLF or NAML L_RLF field The related files name block must specify the address of a valid file specification in the resultant string NAM L_RSA NAM B_RSS or NAML L_LONG_RESULT NAML L_LONG_ RESULT_ALLOC field Typically an RMS file service other than Parse places the file specification in the resultant string You can specify whether the related file is used as an input file specification or an output file specification by setting output file specification parsing or resetting input file specification parsing the output file parse FAB V_OFP bit in the file processing options FAB L_FOP field When an input file specification is being parsed you can have multiple related name blocks by specifying the second related file s name block address in the NAMS L RLF or NAML L_RLF field of the first related name block the address of the third related name block in the NAM L_RLF or NAML L_RLF field of the second name block and so forth The use of multiple
248. enVMS RMS hereafter referred to as RMS operation For example when an application needs data the disk controller must first search for the data on the disk The disk controller must then transfer the data from the disk to main memory After processing the data the program must provide for returning the results to mass storage via the I O subsystem One way to reduce I O time is to have the data in memory so that you can minimize search and transfer operations If data must be transferred to memory for processing you should consider design variables that reduce transfer time The first variable you might consider is the set of file attributes that may affect T O time e Initial file allocation e Default extension quantity e Bucket size for a relative or indexed file Performance Considerations 3 1 Performance Considerations 3 1 Design Considerations e Number of keys for an indexed file e Number of duplicate key values for an indexed file The second variable is the file size as measured by the number of records in the file File size affects the time it takes to scan a file sequentially or to access records using an index A third variable is the storage device on which your program and data files reside Crucial to I O performance are the type of device chosen moving head fixed head and so on and the amount of I O activity for that device within the system To make your applications run faster consider the following
249. ens to the originals In other words you need to back up your files Then if something does happen to your original data you can restore the duplicate files The Backup utility BACKUP allows you to create backup copies of files and directories and to restore them as well These backup copies are called save sets and they can reside on either disk or magnetic tape Save sets are also written in BACKUP format only BACKUP can interpret the data Unlike the DCL command COPY which makes new copies of files updating the revision dates and assigning protection from the defaults that apply BACKUP makes copies that are identical in all respects to the originals including dates and protection To use the Backup utility to create a save set of your file use the following command syntax BACKUP input filespec output filespec SAVE SET You have to use the SAVE SET qualifier only if the output file will be backed up to disk You can omit the qualifier for magnetic tape For more information about BACKUP see the description of the Backup utility in the OpenVMS System Management Utilities Reference Manual Maintaining Files 10 29 A Edit FDL Utility Optimization Algorithms This appendix lists the algorithms used by the Edit FDL utility to determine the optimum values for file attributes A 1 Allocation For sequential files with block spanning the Edit FDL utility allocates enough blocks to hold the specified number of record
250. ense from Compaq required for Il possession use or copying Consistent with FAR 12 211 and 12 212 Commercial Computer Software Computer Software Documentation and Technical Data for Commercial Items are licensed to the U S Government under vendors standard commercial license Module li Determine ODS Level C Abstract li Main sole module for a program to display the Il the on disk structure level e g ODS 2 ODS 5 of a disk device based on the ACP type identified Lis by the SYSSGETDVI system service li li The device is identified by name via the string deviceName specified below Ls li To Build OpenVMS Alpha li CC Determine ODS Level NODEBUG OPTIMIZE Hs LINK Determine ODS Level NODEBUG Il RUN Determine ODS Level NODEBUG Hs Include Header Files include lt descrip h gt include lt dvidef h gt include lib routines h define NEW STARLET 1 include lt starlet h gt include iosbdef h include lt stdio h gt include lt string h gt Structure Definitions pragma member alignment save pragma nomember alignment typedef struct item list 3 unsigned short bufflen unsigned short itemcode unsigned long buffaddr signed long retlenaddr unsigned int terminator ITEM LIST 3 pragma member alignment restore VMS descriptors SYSSGETDVI arguments lib signal for built in IO
251. ensure a read only global buffer cache operate on the file without record interlocking or disallow all other accessors from accessing the file You specify file sharing values using the SHARING primary attribute or the FAB B_SHR field Allows you to provide record locking for a shared file under user control By default RMS automatically locks records depending on the file access and file sharing values specified For additional information see Section 7 2 You specify the record locking values using the CONNECT primary attribute or using the record processing options RAB L_ROP field Indicates an option that can be specified for each record processing operation For more information see Section 9 3 9 2 2 File Specifications As described in Chapter 4 and Chapter 6 the program should specify the specification for the file being opened or created and can also specify default file specifications The file specifications are summarized in the following table File Specification Description Primary 9 6 Run Time Options Specifies the file specification to be used to locate the desired file s If any components of a file specification are omitted RMS applies defaults but you should specify the primary file specification e FDL FILE NAME e RMS FAB L FNA and FABS B FNS Run Time Options 9 2 Options Related to Opening and Closing Files File Specification Description Default Specifies the
252. ent record position effectively deleting the record at that location and all records following it so you need only use Put services to extend the file Note that you can truncate only sequential files In random access mode the Find or Get service and the Put service do not affect the next record position unless these services are used to add a record with a primary key value or a record number that lies between the corresponding values of the current record and the next record previous record for reverse search key options When this occurs the current record position is changed to reflect the location of the added record that is records are added after the current record not before the next record In sequential access mode the Put service initializes the next record position to the end of the file in a sequential file In a relative file the Put service initializes the next record position to the next record or record cell For sequential accesses to an indexed file the Put service does not define the next record position Record Processing 8 17 Record Processing 8 6 Current Record Context Regardless of access mode the Delete Update Free and Release services have no effect on the next record position For sequential and relative files the Rewind service establishes the next record position as the first record or record cell in the file regardless of the access mode For indexed files the Rewind service always establishe
253. ent that begins with a square bracket must end with a square bracket and a directory component that begins with an angle bracket must end with an angle bracket The directory component contains a series of subdirectory names separated by periods Examples of legal directory components are DLEVELO DLEVELO DLEVEL1 DLEVELO DLEVEL1 DLEVEL2 DLEVELO DLEVEL1 gt Note An alternate form of subdirectory name supported by RMS only on Alpha systems on both ODS 5 and ODS 2 disks is that of a directory ID referred to as DID This form is described in Chapter 6 5 8 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 2 File Specification Components A subdirectory name may contain a period To be distinguishable from the delimiter periods it must be specified to RMS as 5 2 7 The File Name Type and Version Components On Alpha systems RMS identifies the file name file type and file version components from the portion of a file specification that follows any node device root and directory components as follows The right most semicolon or period followed by legal version characters begins the version component semicolon unescaped followed by characters that are not legal for a version component is illegal The right most period to the left of the version if any begins the type component The characters to the left of the type are the file name Legal forms o
254. ently the access pattern exhibits temporal locality but because it adds records sequentially to the end of the file the access pattern also exhibits spatial locality When you add records to a relative file you might consider choosing the deferred write option FDL attribute FILE DEFERRED WRITE FAB L_FOP field FAB V DFW With this option the contents of the write buffer are not transferred from memory to disk until the buffer is needed for another purpose or until the file is closed Note however that the possibility of losing data during a system crash increases when you use the deferred write option To see what the current default buffer count is give the DCL command SHOW RMS DEFAULT To set the default buffer count use the DCL command SET RMS_DEFAULT RELATIVE BUFFER_COUNT n where n is the number of buffers 3 4 3 Global Buffer Option If several processes share a relative file you may want to specify that the file use the global buffer option A global buffer is an I O buffer that two or more processes can access If two or more processes simultaneously request the same information from a file each process can use the global buffers instead of allocating its own dedicated buffers Only one copy of the buffers resides at any time in memory although the buffers are charged against each process s working set size Using the global buffer option to form a memory cache may not reduce the number of I O operations necessary to proc
255. er Longest record access times Potential range of key values not physically present as in relative file organization Variety of data formats for keys Transparent data compression 2 26 Choosing a File Organization 3 Performance Considerations When you design a file your decisions regarding record access mode record format and file organization should be aimed at achieving optimum data processing performance for your application This chapter discusses general performance considerations and specific trade offs you can make in the design of your data files In Section 3 3 Section 3 4 and Section 3 5 these trade offs are discussed in the contexts of the three file organizations sequential relative and indexed 3 1 Design Considerations 3 1 1 Speed In designing files for optimum data processing performance you should emphasize the following performance factors e Speed You want to maximize the speed with which your program processes data e Space You want to minimize the space required to store data on disk and to process data in memory e Shared access You want your data to be simultaneously accessible to authorized users e Impact on application design You want to minimize the application design effort The first guideline you can apply to the design process is to decrease the amount of program I O time Storing data on and retrieving data from mass storage devices is the most time consuming Op
256. er interlocking SHARING USER INTERLOCK or FAB B SHR field FAB V UPI set Multistreaming SHARING MULTISTREAM or FAB B SHR field FAB V MSE set If other processes are limited to reading and locating records they are unable to modify or add records and record lock checking is not performed If other processes are allowed to delete add or modify records they can also read records however record lock checking occurs All record access functions use interlocked interprocess file sharing No access denies access to all accessors except the accessor who specifies the option This option might be used when a file is shared infrequently or when doing a major update When you use this option be sure to close the file promptly when other users are trying to access the file Choose this option or the user interlocking option when using block access To use the Queue I O Request system service specify the FILE USER FILE OPEN attribute FAB L FOP field FAB V UFO set The no access option does not allow file sharing and requires that your process have write file protection access User interlocking permits the user to maintain interlocking protection including maintaining the end of file mark For any other form of file sharing RMS controls the reading and writing of I O buffers to ensure the integrity of file and record structures This option is useful for nonshared sequential files and for block I O access using RMS or the Queue I O Request sys
257. er to the specified root directory or directories beneath it in the directory tree A reference to a top level directory refers to a subdirectory of the specified root directory when using rooted directory syntax This is consistent with the fact that the root directory appears as the MFD because a reference to directory 000000 refers to the root directory When you execute the SHOW DEFAULT and other direct commands the system displays the root directory as 000000 Note that the directory specification form 0 0 for the MFD is not valid when using rooted directory syntax For example assume the top level directory ROOT1 on disk DUA7 contains a subdirectory ROOT1 SUB The directory ROOT1 is defined as the root directory associated with the logical name BASE as follows DEFINE BASE DUA7 ROOT1 When you associate the root directory with the logical name base you can refer to the logical top level directory ROOT1 SUB using the syntax BASE SUBJ The following chart provides a summary of the actual directory accessed and the equivalent rooted directory syntax that applies to this example Actual Directory Rooted Syntax Comments DUA7 ROOT1 BASE 000000 ROOT1 appears as the MFD DUA7 ROOT1 SUB BASE SUB ROOT1 SUB appears as a top level directory The next example shows how to define the root logical name described in the previous chart and how to access a subdirectory of the specified root directory Note that
258. erred write option with sequential access because random accesses of the file usually result in several I O operations to bring in the single records Not all operations on indexed files can be deferred Any operation that causes a bucket split forces the writeback of the modified buckets to disk This forced writeback decreases the chances of lost information should a system failure occur Using the deferred write option improves performance if you are performing multiple I O operations on a bucket Consider the following example The indexed file has a single key and its records are 100 bytes long The bucket size is 3 blocks with a fill factor of 67 Thus there is an average of 10 records in each bucket A batch program reads each record and updates part of it beginning at the first record in the file and moving through the records sequentially Without the deferred write option 11 disk I O operations occur for every 10 records one to read the bucket and one to write the bucket for each record With the deferred write option only two disk I O operations occur for every 10 records one to read the bucket and one to write the bucket after the record operations are completed 3 28 Performance Considerations Performance Considerations 3 6 Monitoring RMS Performance 3 6 Monitoring RMS Performance You can improve file performance by gathering statistics on RMS activity Then you can use these statistics to fine tune the file When
259. erted You can also specify an FDL file CONV PASS OPTIONS Indicates the CONVERT qualifiers that you want to use You may specify any legal CONVERT option or you may accept the defaults CONV CONVERT Copies records from one or more source data files to an output data file The output file is not required to have the same file organization and format as the source files The routines must be called in this order Example 4 8 shows how to call the CONVERT routines from a Fortran program Creating and Populating Files 4 27 Creating and Populating Files 4 5 Populating a File Example 4 8 Using the CONVERT Routines in a Fortran Program ox o ook o BOR ook oot ok ot o oto ox w Ge OX 3 1000 This program calls the routines that perform the functions of the Convert utility It creates an indexed output file named CUSTDATA DAT from the Specifications in an FDL file named INDEXED FDL The program then loads CUSTDATA DAT with records from the sequential file SEQ DAT No exception file is created This program also returns the BRIEF CONVERT statistics Program declarations IMPLICIT INTEGER 4 A Z Set up parameter list number of options CREATE NOSHARE FAST LOAD MERGE APPEND SORT WORK FILES KEY 0 NOPAD PAD CHARACTER NOTRUNCATE NOEXIT NOFIXED CONTROL FILL BUCKETS NOREAD CHECK NOWRITE CHECK FDL and NOEXCEPTION i INTEGER 4 OPTIONS 19 1 18 1 0 1 0 0 1 2 0 0 0 0 0 0 0 0 0 1 0 Set up statistics
260. ervice As with the Put service your program must provide a buffer within the data portion of the program to hold the record that is to be updated When calling RMS directly the program must also supply the length of each record to be written This is a constant value when updating fixed length records but varies from record to record when updating variable length records or VFC records Note that some high level language compilers may automatically handle record buffer allocation and size specification or may supply a means to simplify its specification Your program must establish the current record position before it updates a record If the file is shared the service that establishes the record position should also lock the record When you update indexed file records take care not to alter the value of any key field that has been specified as unchangeable for example the primary key To change the value of a record s primary key you must replace the existing record with a new record having the desired primary key value You can do this using the Put and Delete services respectively or where applicable you may use the Put service with the update if RAB L ROP RAB V UIF option When updating indexed file records you do not have to specify the key of reference For more information about the Update service and record processing options refer to the OpenVMS Record Management Services Reference Manual 8 2 4 Deleting Records
261. ervice ignores the option and adds the record 7 12 File Sharing and Buffering File Sharing and Buffering 7 2 Record Locking 7 2 2 7 Summary This section provides two tables to summarize the information described in Sections 7 2 2 1 through 7 2 2 6 The record locking options that control record access exhibit varying degrees of compatibility Table 7 6 summarizes access control locking compatibility by comparing the type of access being requested by a record stream with the current lock held by another record stream The table does not take into account miscellaneous record locking options notably the read regardless option Table 7 6 Compatibility of Record Locking Options Current Lock Held by Another Record Stream Requested Access EXCLUSIVE WRITE READ None EXCLUSIVE NO NO NO YES WRITE NO NO NO YES READ NO NO YES YES NO LOCK NO YES YES YES 1RMS OK RLK is returned The next table lists record locking options that control record access and how you select each option through the FDL and RMS interfaces Option Interface How to Select Exclusive FDL This is the default when you do not select write locking locking RMS read locking or no locking Write locking FDL CONNECT LOCK ON WRITE RMS RAB L ROP RAB V RLK Read locking FDL CONNECT LOCK ON READ RMS RAB L ROP RAB V REA No locking FDL CONNECT NOLOCK RMS RAB L ROP RAB V NLK 7 2 3 Handling Record Locking Conflicts Application progr
262. ervices are also available For more information about both types of processing services and the options that apply to each see the OpenVMS Record Management Services Reference Manual 8 4 Record Access for the Various File Organizations To retrieve or insert a file record for a particular record stream your program must specify either sequential or random access Record Processing 8 5 Record Processing 8 4 Record Access for the Various File Organizations Sequential access can be used with all file organizations For sequential files sequential access implies that records are accessed according to their physical position in the file For relative files sequential access implies that records are accessed according to the ascending order of relative record numbers In indexed files sequential access implies that records are accessed according to a specified ordering of values for a particular key or keys Random access is defined as one of the following e Random access by key for indexed files implies that RMS uses the specified key value contained within the record itself to locate the desired record e Random access by relative record number for relative files and for sequential files having fixed length records implies that the specified relative record number is used to locate the desired record The relative record number does not necessarily reside in the record e Random access by RFA implies that the specified RFA is used
263. es the best use of buffers The two extremes of record access are when records are processed either completely randomly or completely sequentially Also there are cases in which records are accessed randomly but may be reaccessed random with temporal locality and cases where records are accessed randomly but adjacent records are likely to be accessed random with spatial locality In completely sequential processing the first record may be located randomly and the following records accessed sequentially records are usually not referenced more than once For best performance you should specify one buffer with a large bucket size unless you use the read ahead option which requires two buffers Large buckets hold more records so you can access a greater number of records before performing I O operations However a small multibuffer count such as the default of 1 buffer is sufficient When you want to improve sequential access performance you may get better results by tuning the bucket size rather than changing the number of buffers 3 16 Performance Considerations Performance Considerations 3 4 Tuning a Relative File Completely random processing means that records are not accessed again and adjacent records are not likely to be accessed You should use one buffer with a minimal bucket size You do not need to build a memory cache because the records are likely to be scattered throughout the file New requests for records most l
264. es the file If there are other writers of a shared sequential file then ACP truncation requests are ignored However the ACP truncation request of the last writer to close the file will be honored ACP truncation of a sequential file can be automatically requested by RMS if an auto extend has been done during this file access and no file default extend quantity exists to be used for the auto extend Using ACP truncation in this instance avoids wasting space when auto extending with a less precise extend quantity default such as the system default extend quantity 3 2 1 5 Units of I O Another file design consideration is to reduce the number of times that RMS must transfer data from disk to memory by making the I O units as large as possible Each time RMS fetches data from the disk it stores the data in an I O memory buffer whose capacity is equal to the size of one I O unit A larger I O unit makes more records immediately accessible to your program from the I O buffers In general using larger units of I O for disk transfers improves performance as long as the data does not have to be swapped out too frequently However as the total space used for I O buffers in the system approaches a point that results in excessive paging and swapping increasing I O unit size degrades system performance Performance Considerations 3 9 Performance Considerations 3 2 Tuning RMS performs I O operations using one of the following I O unit types
265. ess by key value key relative file The relative record number of each data record cell in a data file RMS uses the relative record numbers to identify and access data records in a relative file in random access mode See also relative record number local buffer A buffer that is dedicated to one process locate mode Technique used for a record input operation in which the data records are not copied from the I O buffer but a pointer is returned to the record in the I O buffer See also move mode move mode Technique used for a record transfer in which the data records are copied between the I O buffer and your program buffer for calculations or operations on the record See also locate mode multiblock An I O unit that includes up to 127 blocks Use is restricted to sequential files multiple extent file A disk file having two or more extents native mode The processor s primary execution mode in which the programmed instructions are interpreted as byte aligned variable length instructions that operate on the following data types byte word longword and quadword integers floating and double floating character strings packed decimals and variable length bit fields The other instruction execution mode is compatibility mode OpenVMS RMS See RMS Record Management Services primary key The mandatory key within the data records of an indexed file used to determine the placement of records within the file and
266. ess the file in all cases Regardless of how many global buffers you allocate RMS always allocates one I O buffer per process which provides efficient buffering capacity Performance Considerations 3 17 Performance Considerations 3 4 Tuning a Relative File If your application has several processes sharing the file and accessing the same records in a transaction sequence then you may benefit from allocating enough global buffers to cache these shared records 3 4 4 Deferred Write Option The deferred write option is a run time option that can improve performance It is the default operation for some high level languages and can be specified by clauses in other high level languages If there is no language support you can use a VAX MACRO subroutine to set the FAB V DFW bit in the FAB L_FOP field before opening the file When you select the deferred write option RMS delays writing a modified bucket to disk until the buffer is needed for another purpose or until another process needs to use the bucket This delay improves performance because it reduces the number of disk I O operations You achieve the largest performance gains using the deferred write option with sequential access file operations For example in a relative file with 100 byte records and 2 block buckets 10 records fit in one bucket Without the deferred write option writing records 1 through 10 in order results in eleven I O operations one for the initial file access
267. estion a range of acceptable values for example 50 100 or the value type for example Keyword YES NO and so forth in parentheses and the default answer in brackets One of the questions in the INDEXED script is shown as follows Number of Keys to Define 1 255 1 4 10 Creating and Populating Files Creating and Populating Files 4 1 File Creation Characteristics In this example the Edit FDL utility prompts you for the number of keys you want to define for an indexed data file The Edit FDL utility accepts any number from 1 to 255 If you do not specify a value it assumes that you want to define one key only the primary key To accept the default value press the Return key If the Edit FDL utility requires that you enter a value that is no default value is specified for the response it includes a dash within brackets When you specify the SEQUENTIAL script or the RELATIVE script the Edit FDL utility returns you to the main menu level after finishing the dialog When you specify the INDEXED script one of the prompts requests your choice of a design graphics display a Line Plot graph or a Surface Plot graph After finishing the dialog the Edit FDL utility displays the selected graph to help you make your final design choice The Line Plot graph plots bucket size against index depth All things equal the size of the buckets determines the number of levels in the index and the number of levels has a direct effect on t
268. et list file is listed in the MFD as VOLSET SYS 1 This file is used only on relative volume 1 of a volume set The file contains a list of the labels of all the volumes in the set and the name of the volume set 1 2 2 7 Continuation File The continuation file is listed in the MFD as CONTIN SYS 1 This file is used as the extension file identifier when a file crosses from one volume to another volume of a loosely coupled volume set This file is used for all but the first volume of a sequential disk save set 1 2 2 8 Backup Log File The backup log file is listed in the MFD as BACKUP SYS 1 This file is reserved for future use 1 2 2 9 Pending Bad Block Log File The pending bad block log file is listed in the MFD as BADLOG SYS 1 This file contains a list of suspected bad blocks on the volume that are not listed in the bad block file 1 10 Introduction Introduction 1 2 Disk Concepts 1 2 2 10 Security Profiles File VAX Only This file contains the volume security profile and is managed with the SET SHOW security commands 1 2 3 Files 11 On Disk Structure Level 1 Versus Structure Level 2 For reasons of performance and reliability Files 11 On Disk structure level 2 a compatible superset of structure level 1 is the preferred disk structure on an OpenVMS system At volume initialization time see the INITIALIZE command in the OpenVMS DCL Dictionary structure level 2 is the default On VAX systems structure level 1 should b
269. et splits because they use additional disk space and CPU time An extra I O operation is required to access a record in a split bucket when the program accesses a record by an alternate key or by RFA Alternate keys have a direct impact on I O operations CPU time and disk space The number of I O operations and the CPU time required for Put Update and Delete operations are directly proportional to the number of keys For example inserting a record with a primary key and three alternate keys takes approximately four times longer than inserting a record with only a primary key To update the value of an alternate key you have to traverse the alternate index structure twice and bucket splits are more likely to occur Randomly accessing an alternate key generally requires an extra I O operation over a comparable access by the primary key and extra disk space is required to store each alternate index structure Alternate keys are more likely than primary keys to have duplicate values For example the zip code is a common alternate key However allowing many duplicate values can have a performance cost Duplicate values can cause clustered record or pointer insertions in data buckets long sequential searches a large number of I O operations and loss of physical contiguity due to continuation buckets especially for the primary key Where possible you should validate record keys before inserting the record especially when you have primar
270. et the journaling parameters of the file KEY y attributes define the characteristics of key y RECORD attributes set the non key aspects of each record SHARING attributes set the run time sharing mode of the file SYSTEM attributes document operating system specific items TITLE is the header line for the FDL file Enter Desired Primary Keyword FILE CONNECT Legal CONNECT Secondary Attributes ASYNCHRONOUS yes no NOLOCK yes no BLOCK IO yes no NONEXISTENT RECORD yes no BUCKET CODE number READ AHEAD yes no CONTEXT number READ REGARDLESS yes no END OF FILE yes no TIMEOUT ENABLE yes no FAST DELETE yes no TIMEOUT PERIOD number FILL BUCKETS yes no TRUNCATE ON PUT yes no KEY GREATER EQUAL yes no TT CANCEL CONTROL O yes no 6 KEY_GREATER_THAN yes no TT PROMPT yes no KEY LIMIT yes no TT PURGE TYPE AHEAD yes no KEY OF REFERENCE number TT READ NOECHO yes no LOCATE MODE yes no TT READ NOFILTER yes no LOCK ON READ yes no TT UPCASE INPUT yes no LOCK ON WRITE yes no UPDATE IF yes no MANUAL UNLOCKING yes no WAIT FOR RECORD yes no MULTIBLOCK COUNT number WRITE BEHIND yes no MULTIBUFFER COUNT number Q Enter CONNECT Attribute Keyword LOCK ON WRITE CONNECT LOCK_ON_WRITE Enter value for this Secondary Yes No YES Resulting Primary Section coNNECT LOCK_ON WRITE yes Press RETURN to continue Z for Main Menu The following list describes the callouts used in Example 9 1 Q This menu is the Main Editor Function menu It d
271. ext key option 8 8 8 9 Equivalence strings 6 4 Erase service 5 22 Error checking 10 1 Exact key match 8 12 EXACT POSITIONING attribute 4 36 EXIT command 10 11 Expanded string 6 4 Expiration date field 1 30 Extend contiguity options and controls 3 8 Extended attribute blocks See XABs Extended character set 5 4 Extending a file 3 4 to 3 9 Extending RMS subdirectories 6 18 Extend operations 3 4 to 3 9 Extend placement controls for various file organizations 3 8 Extends See also Auto extends invoking by way of EXTEND service 3 5 placement and contiguity options 3 8 two methods 3 5 EXTEND QUANTITY qualifier 9 7 EXTENSION attribute 4 36 Extension size A 1 calculating 9 7 performance 9 7 9 8 Index 4 Extents 1 3 1 7 9 7 F FAB B_BKS field 3 25 4 32 7 20 7 21 FAB B_BLS field 4 32 FAB B_DNS field 9 7 FAB B_FAC field 9 6 options 7 3 FAB B_FNS field 6 5 9 6 FAB B FSZ field 4 33 FAB B ORG field 4 32 FAB B RAT field 4 34 FAB B RFM field 4 34 FAB B RTV field 9 8 9 9 FAB B SHR field 9 6 FAB V MSE option 7 24 FAB V SHRGET option 7 24 FAB V UPI option 7 6 list of options 7 4 FAB L ALQ field 4 35 FAB L DNA field 6 3 9 FAB L FNA field 6 3 6 5 9 6 FAB L FOP field 4 31 FAB V CBT option 4 35 FAB V CTG option 4 35 FAB V DFW option 3 17 3 18 3 27 3 28 7 21 7 22 9 8 FAB V MXV option 4 31 FAB V NAM option 6 5 FAB V NE
272. f a version component are lt decimal digit s gt lt decimal digit s gt Hil multiple character wildcard On ODS 2 and ODS 5 disks the numerals in a version component interpreted as a decimal number may not exceed 32767 Note that although RMS accepts a period as a version delimiter in output specifications RMS always uses the semicolon as the delimiter The following are some examples of name type and version Name Type Version Name Type Version A B 1 A B oul A B C A B C none A B C illegal A B 1 A B al A B 1 A B 1 A B 32767 A B 32767 A B A B none none A B C illegal A B 1234567 illegal Note that although RMS on Alpha systems allows periods in a file name files with such names can be created only on ODS 5 disks Note An alternate way of specifying a file within a directory supported by RMS only on Alpha systems on both ODS 5 and ODS 2 disks is that of a file ID referred to as FID This form is described in Chapter 6 On VAX systems and on Alpha systems with versions previous to OpenVMS V7 2 RMS identifies the file name file type and file version components from the portion of a file specification that follows any node device root and directory components as follows e A semicolon or the right most period followed by legal version characters begins the version component e A semicolon followed by characters that are not legal for a version is illegal e A
273. f the question Note too that the utility responds to an invalid response in the same manner that it responds to a question mark Ctrl Z is equivalent to the EXIT command if you use it at the main menu level If you use it from any other level Ctrl Z returns you to the main menu level Creating and Populating Files 4 3 Creating and Populating Files 4 1 File Creation Characteristics In most cases a command from the main menu brings up a second level menu For instance typing the ADD command displays the following menu Legal Primary Attributes ACCESS attributes set the run time access mode of the file AREA x attributes define the characteristics of file area x CONNECT attributes set various RMS run time options DATE attributes set the date parameters of the file FILE attributes affect the entire RMS data file KEY y attributes define the characteristics of key y NETWORK attributes set run time network access parameters RECORD attributes set the non key aspects of each record SHARING attributes set the run time sharing mode of the file SYSTEM attributes document operating system specific items TITLE is the header line for the FDL file Enter desired primary Keyword FILE One of the most important features of the Edit FDL utility is that it helps you create FDL files that define indexed relative and sequential data files To do this the Edit FDL utility provides seven scripts that guide you through an interactive session Y
274. fer cache When records are accessed randomly and adjacent records are apt to be accessed you should specify a single buffer However if your program is processing a file with small bucket sizes you should consider specifying more buffers When the file is likely to be accessed by several methods you should consider a compromise of the number of buffers and bucket sizes When adding records to a relative file consider choosing the deferred write option FDL attribute FILE DEFERRED WRITE FAB L_FOP field FAB V DFW With this option the buffer memory resident bucket into which the records have been moved is not written to disk until the buffer is needed for other purposes or until the file is closed Note that if you use the deferred write option there is a risk that data may be lost if a system crash occurs before the records are written to disk To see the current process default buffer count use the DCL command SHOW RMS DEFAULT To set the process default buffer count use the DCL command SET RMS DEFAULT RELATIVE BUFFER COUNT n where n is the number of buffers 7 3 5 Buffering for Indexed Files With indexed files buckets not blocks are the units of transfer between the disk and memory The bucket size is specified when the file is created although the bucket size of an existing file can be changed by converting the file see Chapter 10 The bucket size is specified by the FDL attribute FILE BUCKET SIZE VMS RMS control bloc
275. ferred Write Option 00 0 eee eeee Monitoring RMS Performance Enabling RMS Statistics Using RMS Statistics Processing in an OpenVMS Cluster Environment OpenVMS Cluster Shared Access 0 0 0 0 eee eee ees Locking Considerations T O Considerations Performance Recommendations 0 000 ce eee eee ee ees 4 Creating and Populating Files 4 1 4 1 1 4 1 1 1 4 1 1 2 4 1 2 4 1 2 1 4 1 2 2 4 1 3 4 2 4 2 1 4 2 2 File Creation Characteristics Using RMS Control Blocks File Access Block Extended Attribute Blocks Using File Definition Language 0 0 eee eee ees Using the Edit FDL Utility Designing an FDL File Using the FDL Routines Creating a File Using the Create Service Using the Create FDL Utility 3 10 3 10 3 11 3 11 3 12 3 12 3 13 3 13 3 13 3 13 3 14 3 14 3 15 3 15 3 16 3 16 3 17 3 18 3 18 3 18 3 18 3 20 3 22 3 22 3 23 3 24 3 25 3 25 3 26 3 27 3 28 3 28 3 29 3 29 3 30 3 32 3 32 3 33 3 33 3 33 4 1 4 3 4 1 4 2 4 2 4 3 4 10 4 13 4 15 4 15 4 16 4 2 3 Using the Convert Utility 0 0 0 0 ees 4 2 4 Using the FDL CREATE Routine 00 0c ce eee eees 4 3 Creating and Accessing Tagged Files l l eee eee 4 3 1 Programming Interface for File Tagging 000005 4 3 2 Accessing a Tagged File llle
276. fications Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concatenation You must access the files using rooted directory syntax whether or not a logical name is used for the rooted directory For example you can legally define the rooted directory logical name MYROOT to be DUAO D1 D2 D3 D4 D5 D6 and nest six subdirectories beneath it using the following directory syntax MYROOT D7 D8 D9 D10 D11 D12 You can also refer to it as the following DUAO D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 But if you try to access this file using the following directory syntax RMS returns a status code that indicates that the file specification is illegal DUAO D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 Note When you are choosing directory tree depths remember that the Backup utility as opposed to BACKUP IMAGE or BACKUP PHYSICAL has depth limits when it is doing file backups See OpenVMS System Manager s Manual Volume 1 Essentials and OpenVMS System Management Utilities Reference Manual A L for information about using the Backup utility 6 4 DID Abbreviated Directories Alpha Only To support Extended File Specifications RMS s user interface was extended to include capacities for the larger specifications that are sometimes necessary to access ODS 5 named files See the OpenVMS Record Management Services Reference Manual To take full advantage of all of the new features applications wou
277. fications 6 2 Understanding RMS Parsing Finally the program must provide the default specification that includes the search list DEF for the directory together with the file type component DEF DAT Given this information RMS looks for FILE DAT using the file specification data in the following order Primary File Default File Specification Specification Expanded String DISK1 BIG DISK1 BIG TEST DAT DISK2 BIG DISK2 BIG TEST DAT DISK1 BEST DISK1 BEST TEST DAT DISK2 BEST DISK2 BEST TEST DAT Now assume the program provides a related file specification with a search list for FILE DAT 1 RMS uses all combinations of the search list elements in the primary and default file specifications with the first component device of the related file specification 2 RMS uses all combinations of the search list elements in the primary and default file specifications with the second component directory of the related file specification 3 RMS repeats steps 1 and 2 with each search list element in the related file specification 6 2 3 2 Special Processing for a Related File Specification This section describes the special processing needed to implement sticky defaults when a search list is used in a related file specification for an input file parse The term sticky default means that file specification components from the first file specification are applied as defaults to the next file specification component
278. figuration llle 1 26 1 11 Blocked Fixed Length Records 0 0 00 e eee eens 1 32 1 12 Variable Length Records 0 0 eee eens 1 32 1 13 Using CONVERT to Create a Data File 02005 1 38 1 14 Using CREATE FDL to Create an Empty Data File 1 39 2 1 Sequential Access to a Sequential File 00005 2 3 2 2 Sequentially Retrieving Records in a Relative File 2 4 2 3 Sequentially Storing Records in a Relative File 2 5 2 4 Random Access by Relative Record Number usn 2 6 2 5 Random Access by Record File Address lllllllllsn 2 8 2 6 Comparison of Fixed and Variable Length Records 2 11 2 7 Writing a VFC Record toa File 0 2 0 0 eee 2 12 2 8 Retrieving a VFC Record 0 2 0 0 cee 2 13 2 9 Sequential File Organization leere 2 16 2 10 Relative File Organization llle eee 2 17 2 11 Variable Length Records in Fixed Length Cells 2 18 2 12 Single Key Indexed File Organization 000e eee 2 22 2 13 Multiple Key Indexed File Organization 005 2 23 3 1 RMS Index Str cture 2 veo aware fGen wx Ope PW er Y qe 3 21 7 3 8 1 10 1 10 2 10 38 10 4 10 5 10 6 10 7 10 8 Tables 1 1 1 2 1 3 1 4 1 5 1 6 2 1 0 5 2 3 2 4 2 5 4 1 4 2 6 1 6 2 7 1 7 2 7 3 7 4 7 5 7 6 8 1 8 2 8 3 10 1 Primar
279. file consists of a series of fixed length record positions or cells numbered consecutively from 1 to n that enables RMS to calculate the record s physical position on the disk The number referred to as the relative record number indicates the record cell s position relative to the beginning of the file RMS uses the relative record number as the key value to randomly access records in a relative file The preferred method of tracking relative record numbers is to assign them based on some numeric field within the record for example the account number See Section 2 1 1 2 for a description of random access by key Each record in the file may be randomly assigned to a specific cell For example the first record may be assigned the first cell and the second record may be assigned the third cell leaving the second cell empty Unused cells and cells from which records have been deleted may be used to store new records Figure 2 10 illustrates the relative file organization Figure 2 10 Relative File Organization Relative Cells First Second Third Fourth Fifth Record Record Record Record Record Written Written Written Written Written ZK 0743 GE In a relative file the actual length of the individual records may vary that is different size records can be in the same file up to the limits imposed by the specified cell length For example think of a relative file configured as shown in Figure 2 11 Choosing a File Organizati
280. file name in quotation marks on input the operating system parses the file name as an OpenVMS file name Input AB2 amp D FgHI k4 M 2 SEER RE DWDEVOP DAT VMS LONG FILENAME LONG FILETYPE Output to User Process AB2 amp D FGHI K4 M 2 win Le TOT eg v qr DWDEVOP DAT VMS LONG FILENAME LONG FILETYPE Output to HDR1 Label AB2 amp D FGHI K4 M Hee HH HH HE EEE HH HH panna n ogg DWDEVOP DATHHHEHEHE VMS LONG FILENAME Introduction 1 29 Introduction 1 3 Magnetic Tape Concepts File Set Identifier Field The 6 character file set identifier field denotes all files that belong to the same volume set The file set identifier for any file within a given volume set should always be the same as the file set identifier of the first file on the first volume that you mount The file set identifier is the same as the volume identifier of the first volume that you mount File Section Number and File Sequence Number Fields The file section number is a 4 character field that specifies the number of the file section The file sequence number is a 4 character field that specifies the number of the file in a file set Generation Number and Generation Version Number Fields The generation number a decimal number from 0001 to 9999 and generation version number a 2 digit decimal number fields store the file version number specified on input and written by the system on output The operating system does not increme
281. file specification used to access the file and its associated file identifier e Returns the length of each component of a file specification as well as other information about the file specification Some file services including the Open and Create services cannot process a file specification that contains wildcard characters If a file specification contains wildcard characters you must use the Search service to resolve the wildcard characters before you invoke the Open service or the Create service The Parse service determines whether wildcard characters or search lists are present and it initializes control block fields that are necessary to search for multiple files using the Search service To use the Search service a name block NAM or NAML must be present when the Parse service is invoked Locating and Naming Files on Disks 5 21 Locating and Naming Files on Disks 5 8 Introduction to File Parsing 5 9 Using Alternatively you can use the SYS FILESCAN system service scan string for file specification to scan a file specification for validity and optionally return the lengths of the individual file specification components without translating logical names or applying defaults Two Run Time Library routines LIB FIND_FILE and LIB FILE_SCAN perform functions that are similar to the SYS SEARCH system service For more information about how RMS parses a file specification see Section 6 1 For additional information about using
282. format Glossary 7 Glossary 8 track A collection of blocks at a single radius on one recording surface of a disk tuning The process of designing your files to achieve better processing performance user buffer A buffer within an application program variable length record format Property of a file in which record length may vary variable length with fixed length control field VFC record format Property of a file in which records of variable length contain an additional fixed length control field capable of storing data that may have no connection with the other contents of the record VFC record format is not applicable to indexed files VFC record format See variable length with fixed length control field VFC record format volume disk An ordered set of 512 byte blocks The medium that carries Files 11 On Disk Structure files volume magnetic tape A reel of magnetic tape which may contain a part of a file a complete file or more than one file volume set A collection of related volumes write behind processing A software option used for sequentially accessing sequential files using two buffers One buffer holds records to be written to the disk The other buffer awaits I O completion A Access See also Random access Record access direct 1 2 random 3 16 sequential 1 2 3 16 shared 10 28 in an OpenVMS Cluster 3 32 tofiles 1 31 to process permanent files 6 21 ACCESS at
283. g eae d rA ea Pa Ce hee d Making Archive Copies 0 0 00 ccc eee eee ees A Edit FDL Utility Optimization Algorithms A 1 A 2 A 3 A 4 A 5 Glossary Index Examples 2 1 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 AW OG ATION 25 0255 35 88 we Beers Lo Gi ado ares ee Bo Mao wk Gy oso he TT ITE WXtEnS1ON SIZE ceser ak ok eee ORS oe eh PW OES RES RAE FMR Dice pies B cket SIZE 52 55 59s ead wie Re Pah Dw a bsc DE cero A Oe EOD ees Global Butters is cece BORE DE OUR SEO Sows DERN SSA RODA RE EOL Index Depth o Seo bee Oe de ee Ie oe p ttu Roe On e Creating a File Containing Collated Keys sslslun Sample Edit FDL Utility Session 20 0000 cc eee ee Sample FDE Fil 4524 5 59 2 eh oo ta usce Mee ae doh eae ag dake es Using FDL Routines in a Pascal Program 200 Using the FDL CREATE Routine in a Fortran Program Using the FDL CREATE Routine from a COBOL Program Tagging a Eile 25 252205 8 poena a eoe abo he wie oO Se bar Accessing a Tagged File llllll elle Using the CONVERT Routines in a Fortran Program 9 13 9 14 9 14 9 15 9 18 9 20 9 21 9 22 2 25 4 5 4 9 4 14 4 17 4 18 4 21 4 24 4 28 4 9 Using the CONVERT Routines in a COBOL Program 4 29 5 1 Using Logical Names for Remote File Access 00005 5 19 5 2 Selecting the USEROPEN Option to Call a Routine 5 24 5 3 Using the
284. get record The current record position also facilitates sequential processing on disk devices for a stream The following list describes situations where the current record position is undefined e When a RAB is first connected to a FAB e When a record operation is unsuccessful e Following the successful execution of a service other than a Get service or Find service When the current record position is undefined RMS rejects the Update Delete Release or Truncate service A Get service using sequential record access mode and immediately preceded by the Find service operates on the record specified by the current record position If the Find service does not lock the record for relative and indexed files and the current record is deleted the Get service accesses the record at the next record position 8 16 Record Processing Record Processing 8 6 Current Record Context Following successful execution of the Get service or the Find service the current record position is set to the target record s RFA RMS also places the target record s address in the RFA field of the related RAB The results are as follows e After initialization the current record position reflects the RFA of the record that was the object of the most recent successful Get service or Find service unless a failure occurs on a different service e Unless it is modified the RAB W_RFA field always contains the address of the target current record If the ope
285. gh level languages include a clause that sets window size when a file is opened You can set the window size FAB B_RTV field at run time with a VAX MACRO subroutine or with the FDL attribute FILE WINDOW SIZE You can increase the default window size for a specific volume by using the DCL commands MOUNT and INITIALIZE However using additional window pointers increases system overhead The window size is charged to your buffered I O byte count quota and indiscriminate use of large windows may result in exceeding the buffered I O byte count quota or may exhaust the system s nonpaged dynamic memory You can use the Backup utility BACKUP to avoid having too many extents When you restore a file BACKUP tries to write the file in one section of the disk Although BACKUP does not necessarily create a contiguous copy of the file it does reduce the number of extents If you are regularly backing up the file the number of extents is probably reasonable For more information about BACKUP see the OpenVMS System Manager s Manual Where disk space is available you can reduce the number of extents by creating a new contiguous version of the file using either the Convert utility CONVERT or the DCL command COPY CONTIGUOUS If neither of these conditions apply a larger window size is the only option to use For file maintenance information see Chapter 10 9 2 3 3 Summary of Performance Options The following table summarizes the run time open an
286. gram at the expense of other File Sharing and Buffering 7 19 File Sharing and Buffering 7 3 Local and Shared Buffering Techniques application programs Have your system manager consult the Guide to OpenVMS Performance Management 1 When records are accessed sequentially a large buffer or buffers should be used Contiguous records in a file are read into memory in one or more blocks for sequential files or in buckets multiblock units for relative and indexed files After the blocks or buckets are read into the buffer area provided by RMS later access to adjacent records would access records in the same block or bucket in the buffer This eliminates additional I O and improves performance When a record is needed that is not in the current buffer cache one of the buffers is replaced by the blocks or the bucket that contains the new record When records in the file are repeatedly accessed using more than one buffer can hold the previously accessed records in memory longer and eliminate an I O operation when the program accesses the records again The buffers that the application program requests RMS to allocate for its use are referred to as a buffer cache and can be thought of as a buffer pool for your process RMS uses buffer caches to locate records first before attempting I O to the target device When many processes share a file the program can use a shared global buffer cache See Section 7 3 6 7 3 3 Buffering for Sequential
287. h control field VFC format e Stream format 2 8 Choosing a File Organization Choosing a File Organization 2 1 Record Concepts The fixed length and variable length record formats are supported for all three file organizations The variable length with fixed length control field VFC record format is supported only for sequential and relative files Note In relative files all records are in fixed length cells regardless of their format RMS supports the stream format for sequential files only At the VAX MACRO level you may specify the record format for a file directly by using the FAB B_RFM field in the FAB 2 1 2 1 Fixed Length Record Format When you specify fixed length record format all file records are the same length and each record begins on an even byte boundary For example when you specify 9 byte fixed length records each block can hold up to 51 records 512 10 not 56 records 512 9 When you accept the block span option the default the maximum fixed length record size for sequential files is 32767 bytes If you specify no block spanning the maximum fixed length record size is 512 bytes one block For additional information about selecting the block span option see the OpenVMS Record Management Services Reference Manual The record length set at file creation time cannot be changed It becomes part of the information that RMS stores and maintains for the file For the fixed length record for
288. h each top level directory you can create subdirectories referenced from the top level directory Advanced Use of File Specifications 6 11 Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concatenation Once the subdirectories are created you can create subdirectories referenced from each subdirectory You can create a large number of levels of subdirectories beneath a top level directory The subdirectories created beneath a directory and the subdirectories within the subdirectories and so forth are called collectively a directory tree The base point for normal directory syntax access can be relative to the current position in the directory tree or an absolute reference that explicitly or by default states any higher level directories or subdirectories needed to identify the appropriate directory or subdirectory An absolute directory reference begins with a directory name a relative directory reference begins with a hyphen or a period An absolute reference might include the name of the top level directory and one or more subdirectories relative directory reference relies on the use of the process default directory and device which are set using the DCL command SET DEFAULT Refer to the OpenVMS DCL Dictionary for additional information and examples A relative directory reference can be in one of several forms Assume the current directory position process default directory is SMITH JONES
289. h interleaving but ISO 9660 file extents may be interleaved That is ISO 9660 extents may consist of logical block groupings that are separated by interleaving gaps In order to make the OpenVMS file system compatible with interleaving the Files 11 C D ACP treats each of the interleaved logical block groups as an extent Undefined Record Format ISO 9660 CD ROMs may be mastered without a specified record format because the ISO 9660 media can be mastered from platforms that do not support the semantics of files containing predefined record formats See the OpenVMS System Manager s Manual for details about mounting media with undefined record formats Introduction 1 15 Introduction 1 2 Disk Concepts 1 2 5 4 Using DIGITAL System Identifiers on CD ROM When an ISO 9660 formatted CD ROM contains information written according to Compaq specifications affected records may include a DIGITAL System Identifier DSI in the associated extended attribute records XAR This section describes how DIGITAL System Identifiers are recorded on ISO 9660 media and how a DSI is used to encode OpenVMS formatted information on the media Figure 1 4 illustrates the DSI and FAT structures in an XAR On ISO 9660 media XARs include fields for specifying a system identifier in byte positions 85 to 116 see A Figure 1 4 Immediately preceding the DSI structure the XAR contains three fields containing record information If the area immediately following
290. h the file and area default extension quantities by specifying the appropriate values in the FAB or XABALL used as input to the CREATE service The FAB W DEQ field defines the file default extension quantity For indexed files with multiple areas individual area XABALLs with the XAB B AID field and the related XAB W_DEQ field set appropriately establish area default extension quantities 3 6 Performance Considerations Performance Considerations 3 2 Tuning If you use this method you can determine the default extension quantities using file and area specific information such as the average record size the number of records to be added to the file during a given period of time the number of records per bucket and the bucket size When both a FAB and a XABALL are present on the opening or creation of an RMS file the XABALL fields override equivalent FAB fields If the XABALL is present then the file default extension quantity is set from the XAB W DEG overriding any value in the FAB W_DEQ field In the case of an indexed file with multiple areas where multiple XABALLs might exist the file default extension quantity is set to the default extension quantity for Area 0 A single allocation XAB XABALL can also be specified on the creation of a relative or sequential file However there is no separate area default extension quantity maintained for these files The XABALL is used in this case to establish the file default extension
291. hange an existing index An interactive session is controlled by these Edit FDL utility scripts You can invoke a script in two ways e You can select the INVOKE command from the main menu and then choose your script When you answer the script questions the Edit FDL utility displays a list of FDL attributes and their assigned values At this point you 4 4 Creating and Populating Files Creating and Populating Files 4 1 File Creation Characteristics can use the Edit FDL utility commands to further modify the attribute values or to end the editing session e You can begin a script by entering a DCL command in the following form EDIT FDL SCRIPT script name This command bypasses the main menu to directly display the menu for the selected script Example 4 1 shows a sample session with the Edit FDL utility Example 4 1 Sample Edit FDL Utility Session OpenVMS FDL Editor Add to insert one or more lines into the FDL definition Delete to delete one or more lines from the FDL definition Exit to leave the FDL Editor after creating the FDL file Help to obtain information about the FDL Editor Invoke to initiate a script of related questions Modify to change existing line s in the FDL definition Quit to abort the FDL Editor with no FDL file creation Set to specify FDL Editor characteristics View to display the current FDL Definition O Main Editor Function Keyword Help INVOKE Script Title Selection Add Key modeling a
292. he checking of a user s access to a volume except as noted in the OpenVMS System Manager s Manual 1 3 1 5 2 VOL2 Label In addition to the first volume VOL 1 label described above OpenVMS systems provide a second volume VOL2 label the volume owner field The volume owner field contains the OpenVMS protection information that has been written on the magnetic tape A second volume label is written only if an OpenVMS protection scheme had been specified on either the MOUNT or INITIALIZE command The volume owner field also contains a value that incorporates the user identification code UIC with the OpenVMS protection code specified for a volume By default OpenVMS systems do not write a UIC to this field thus allowing all users READ and WRITE access Note however that EXECUTE and DELETE access are not applicable to magnetic tape volumes Also note that regardless of the protection code that you specify both system users and the volume owner always have READ and WRITE access to a volume The contents of the volume owner field depends on the OpenVMS protection code that you specify Introduction 1 27 Introduction 1 3 Magnetic Tape Concepts 1 3 1 6 Header Labels OpenVMS operating systems support four file header labels HDR1 HDR2 HDR3 and HDR4 The HDR3 and HDRA labels are optional The following sections describe and illustrate each file header label 1 3 1 6 1 HDR1 Label Every file on a volume has a HDR1 label which
293. he record to be written e FDL None e RMS RAB L_RBF Specifies the size of the record contained in the record buffer to be written e FDL None e RMS RAB W_RSZ Specifies a timeout period after which an error is returned when you choose the wait if locked option The number of seconds is specified by the CONNECT TIMEOUT_PERIOD or the RAB B_TMO field to eliminate a potential deadlock e FDL CONNECT TIMEOUT PERIOD e RMS RAB L_ROP RAB V_TMO and RAB B_TMO Run Time Options 9 19 Run Time Options 9 3 Summary of Record Operation Options Option Description Truncate on Put Update if Write behind Specifies that the file is truncated at the record being added Requires sequential record access and only applies to sequential files e FDL CONNECT TRUNCATE ON PUT e RMS RAB L ROP RAB V_TPT Turns the Put service into an update operation if the record already exists in the file Care must be taken when using this option with shared files and automatic record locking see Section 8 1 When using this option with indexed files note that the file must not allow duplicates for the primary key This option can only be used when random record access has been specified e FDL CONNECT UPDATE_IF e RMS RAB L ROP RAB V UIF Improves performance at the expense of additional memory for I O buffers Requires sequential record access and only applies to sequential files e FDL CONNECT WRITE_BEHIND e RMS RAB L_ROP
294. he beginning of the file to return the previous record whose key value is less than the current key of reference according to sort order Table 8 2 lists the search key types for each option combination Note that three of the listed combinations are not supported not allowed and result in the return of an error message Table 8 2 Search Key Types Search Key Option Settings Search Key Type Reverse Equal or Next Next Equal Off Off Off Equal or greater than Off On Off 1Default forward search key continued on next page Record Processing 8 9 Record Processing 8 4 Record Access for the Various File Organizations Table 8 2 Cont Search Key Types Search Key Option Settings Search Key Type Reverse Equal or Next Next Greater than Off Off On Not allowed Off On On Not allowed On Off Off Equal or less than On On Off Less than previous On Off On Not allowed On On On 2Default reverse search key If you use the reverse search key option with a set of records that has duplicate keys only the first record in the set is returned An application that needs to access all records having duplicate key values requires additional compiler or program logic On disk data structures are designed to provide optimum performance for forward searches Reverse search performance may be diminished especially for applications that process long chains of deleted records To take advantage of built in caching that i
295. he key labeled Ctrl while you press another key or a pointing device button PF1 x A sequence such as PF1 x indicates that you must first press and release the key labeled PF1 and then press and release another key or a pointing device button PF1 x A sequence such as PF 1 x indicates that you must first press and release the key labeled PF1 and then press and release another key or a pointing device button xiv Return O U bold text italic text UPPERCASE TEXT Monospace text In examples a key name enclosed in a box indicates that you press a key on the keyboard In text a key name is not enclosed in a box In the HTML version of this document this convention appears as brackets rather than a box A horizontal ellipsis in examples indicates one of the following possibilities e Additional optional arguments in a statement have been omitted e The preceding item or items can be repeated one or more times e Additional parameters values or other information can be entered A vertical ellipsis indicates the omission of items from a code example or command format the items are omitted because they are not important to the topic being discussed In command format descriptions parentheses indicate that you must enclose choices in parentheses if you specify more than one In command format descriptions brackets indicate optional choices You can choose one or more items or no items Do n
296. he records in the original bucket and transfer the remaining records to a newly created bucket buffer A memory area used to temporarily store data Buffers are generally categorized as being either user buffers or I O buffers cluster The basic unit of space allocation on a Files 11 On Disk Structure volume Consists of one or more contiguous blocks with the number being specified when the volume is initialized contiguous area A group of physically adjacent blocks count field A 2 byte field prefixed to a variable length record that specifies the number of data bytes in the record This field may be formatted in either LSB or MSB format cylinder The tracks at the same radius on all recording surfaces of a disk density The number of bits per inch bpi of magnetic tape Typical values are 800 bpi and 1600 bpi See also bits per inch directory A file used to locate files on a volume A directory file contains a list of files and their unique internal identifications directory tree The subdirectories created beneath a directory and the subdirectories within the subdirectories and so forth disk See volume disk extent One or more adjacent clusters allocated to a file or to a portion of a file FDL See File Definition Language file An organized collection of related items records maintained in an accessible storage area such as disk or tape File Definition Language FDL A special purpose language
297. he run time performance of an indexed file Fewer levels generally reduce the average number of keys searched when the index tree is traversed However fewer levels imply more records per data bucket and may cause longer data bucket search times Thus the Line Plot graph helps you decide on the best bucket size for your application Figure 4 1 shows a Line Plot graph Figure 4 1 Line Plot Graph Index Depth 9 8 7 6 5 4 4 3 33 3 3 3 2 22222222222222222222222222 1 t 1 5 10 15 20 25 30 32 Bucket Size Number of Blocks ZK 0980 GE As shown in Figure 4 1 a bucket size of 1 block results in an index with five levels Increasing the bucket size to 2 blocks reduces the number of index levels to four but an increase to 5 blocks does not reduce the number of index levels at all A bucket size of 7 blocks however reduces the number of index levels to three When you choose the bucket size remember that the graphs do not display the data level For example if you want three levels in the file then you must limit the number of index levels to two The Surface Plot graphics mode lets you choose a range of values to see their effects The Edit FDL utility prompts you to enter a lower and upper bound for one of the following values e Load fill percent e Key length e Record size Creating and Populating Files 4 11 Creating and Populating Files 4 1 File Creation Characteris
298. he set An efficient use of the Find service is to create a table of RFAs record file addresses to be used for rapidly accessing the records in the same file Record retrieval operations are typically used to repetitively read and process a set of records As part of this type of operation your program should check for an end of file condition after each Find or Get service For more information about the Find and Get services refer to the OpenVMS Record Management Services Reference Manual 8 2 2 Inserting Records The Put service adds a record to the file Within the data portion of your program you must provide a buffer for the record to be added When calling RMS directly the program must also supply the length of each record to be written This is a constant value with fixed length records but varies from record to record when adding variable length or VFC records When using high level languages however the language s compiler may automatically specify the record buffer size or supply a means to simplify its specification The current record position is especially important when adding records to a sequential file RMS establishes the current record position at the end of file for any record stream associated with a file opened for adding records To add records to a relative file or to an indexed file use random access by key or record number unless the program adds records sequentially by a specified ordering of primary ke
299. hed the data is consistent Note On VAX systems RMS record locking differs from RMS Journaling for OpenV MS record locking If your application program uses Recovery Unit Journaling see the RMS Journaling for OpenVMS Manual for details The operating system allows you to determine whether the application program or RMS provides record locking Processes accessing the file make this choice by specifying appropriate sharing attributes and access attributes in the FAB as described in Section 7 1 In general RMS enables record locking when record modifications are permitted in a shared file environment RMS provides record locking for all file organizations and uses the lock manager to keep conflicting record streams from updating a record simultaneously The rest of this section describes record locking File Sharing and Buffering 7 7 File Sharing and Buffering 7 2 Record Locking 7 2 1 Default Record Locking You can specify various record locking options in the RAB when you access a record by way of a record stream If you do not explicitly specify any record locking options when you access a record RMS uses default record locking to automatically and transparently lock and unlock shared records Default record locking does not require special handling of locks in the application program In a typical record locking scenario an application program calls a service to access and lock a record The application program then p
300. her OpenVMS software or by terminals is represented by an escape character followed by two hexadecimal digits xx Otherwise it is represented by its own character The following 8 bit values are output as an escape character followed by two hexadecimal digits 7F rubout 80 9F Cl control characters A0 nonbreaking space A0 nonbreaking space FF Latin small letter y diaeresis Locating and Naming Files on Disks 5 5 Locating and Naming Files on Disks 5 2 File Specification Components 5 2 4 4 Simple Characters The set of characters valid through the RMS interface in a file specification without any special escape character includes the following Note that these characters must not be preceded by the escape character e Upper and lowercase alphanumeric characters A Z a z 0 9 e Special ASCII 7 bit characters Dollar sign Minus sign Underscore _ e ISO Latin 1 graphic characters in the range hexadecimal AO to FF 5 2 4 2 Compound Characters Escape followed by a pair of hexadecimal digits is interpreted as a hexadecimal value for an arbitrary and otherwise legal 1 byte character For example 20 represents a space The ASCII code for space is hexadecimal 20 Escape followed by or by a space represents a space Escape followed by U followed by 4 hexadecimal digits is interpreted as a 2 byte Unicode character Escape followed by any of the following characters means that the cha
301. hows the routine Locating and Naming Files on Disks 5 23 Locating and Naming Files on Disks 5 9 Using One File Specification to Locate Many Files Example 5 2 Selecting the USEROPEN Option to Call a Routine TITLE PSECT LOCATE DATA WRT NOEXE EXTERNAL LIBSSIGNAL LIBSSTOP LIBSGET_INPUT LIBSPUT_OUTPUT EXTERNAL STRSGET1_DX SFABDEF SRABDEF i IFILE IFILED BLKB LONG ADDRESS ru OFILED WORD BYTE BYTE OFILE LONG Ld DFILED ASCID D PROMPT LOC P NULL P ARGS ASCID ASCID ASCID LONG ADDRESS ADDRESS ADDRESS ADDRESS ADDRESS ADDRESS ADDRESS LONG LONG BLKL BLKL WORD CTEXT NULL STV L UFLAGS LEN PSECT ENTRY MOVL MOVL BISL2 PUSHAL PUSHAL PUSHAL CALLS BLBC PUSHAL PUSHAL CALLS BLBC CALLG BLBC BRW PUSHL PUSHL CALLS BRW TERR ERR 80 80 IFILE 255 DSC K_DTYPE T DSC K CLASS D 0 DAT Enter the filespec Define FAB symbols Define RAB symbols Input filespec Filespec descriptor Filespec descriptor Specify character text Specify descriptor class Address set by STR GET1 DX Default filespec descriptor User prompt NOTE Global buffers EE x fed 7 IFILED OFILED CTEXT DFILED NULL STV L UFLAGS 0 0 1 1 255 CODE NOWRT EXE LOCATE M R6 R7 4 AP R6 8 AP R7 2 UFLAGS IFILED PROMPT IFILED 3 G LIBSGET INPUT RO TERR OFILED
302. ibuf return continued on next page 5 26 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 9 Using One File Specification to Locate Many Files Example 5 3 Cont Using the Parse and Search Services Loop for all files matching filespec while rms status sys search amp filfab amp STS M SUCCESS Output a row of asterisks the filename and other row of asterisks for i 0 i lt 80 i obuf i obuf 80 N0 puts obuf fbuf filnam nam b rsl 0 Add lt NUL gt terminator puts fbuf puts obuf if fil fopen fbuf r Try to open the file Process the file while fgets obuf MAXLINE fil if strstr obuf ibuf fputs obuf stdout fclose fil Done with this file putchar f Print FF between files if rms_status RMS FNF rms_status RMS NMF rms_ status SS NORMAL Handle expected errors return rms status An application may also need to process either one file or many files depending on the file specification that the terminal user enters or the logical name that is provided if the program uses a logical name in its file specification Each of these cases is discussed in the following sections 5 9 1 Processing One File When only a single file needs to be processed but more than one location for the file may need to be searched you can usually find the file by s
303. ication beginning with the primary file specification string indicated by the contents of the FAB L_FNA and FAB B_FNS fields or by the contents of the NAML L LONG FILENAME and NAML L LONG FILENAME SIZE fields A file specification may have one of three formats e The first file specification is in the following format node foreign filespec node task spec string RMS attempts to translate the node name so that it can determine whether a logical node name is present Only a logical or physical node name including an access control string if present is allowed if the translation is successful If a logical node name is found the translation is repeated When translation cannot be performed the file specification is copied directly into the expanded string The quoted string is not parsed except to determine if it refers to a file or a task on the remote system For additional information about these formats see the DECnet for OpenVMS Networking Manual e If the file specification contains only a name without a terminating period or colon RMS attempts to translate it as a logical name If the file name field is translated successfully the entire translation operation restarts using the equivalence string as input If the file name field is not translated successfully RMS uses it as the file name component e If the file specification is not in either of the formats described previously RMS assumes it to be in the following f
304. ich File Parameter Mnemonic refresh ZK 0950 GE During the final design phase the Edit FDL utility gives you an opportunity to supply values for such attributes as TITLE an optional primary that allows you to label the FDL file Most of these questions are also applicable to designing sequential and relative files When you have answered the questions the Edit FDL utility assigns the values to the FDL attributes and returns you to the main menu level to display the resulting FDL file At the main menu you can select the ADD command to assign values to any attribute the script omitted Remember that if an attribute does not appear in the FDL file it assumes the default value For a list of the default values for each attribute see the OpenVMS Record Management Utilities Reference Manual To modify an attribute use the MODIFY command and to delete an attribute use the DELETE command To create the displayed FDL file select the EXIT command To abort the session without creating an FDL file select the QUIT command 4 1 3 Using the FDL Routines You can also define file creation characteristics with the FDL utility routines The FDL routines provide you with the functions of the File Definition Language and they allow you to set file creation characteristics from within your application There are four FDL routines FDL CREATE Creates a file from an FDL specification and then closes the file See Section 4 2 4 for more inform
305. identifies and describes the file by supplying the OpenVMS MTAACP with the following information e File identifier e File set identifier e File section number e File sequence number e Generation and generation version numbers e File creation and expiration dates e Accessibility code e Implementation identifier File Identifier Field The file identifier field contains the first 17 characters of the file name you specify The remainder of the file name is written into the HDR4 label provided that this label is allowed If no HDR4 label is supported a file name longer than 17 characters will be truncated You may use either an ANSI magnetic tape file name or an OpenVMS file specification of the following format filename type version OpenVMS file specifications are a subset of ANSI magnetic tape file names However ANSI magnetic tape file names are valid only for magnetic tape volumes OpenVMS file specifications are valid for disk and tape volumes Both types of file specifiers are compatible with compatibility mode An OpenVMS file specification consists of a file name a file type and an optional version number Valid file names contain a maximum of 39 characters Valid file types consist of a period followed by a maximum of 39 characters The semicolon separates the version number from the file type Except for wildcard characters only the characters A through Z 0 through 9 and the special characters ampersand amp hy
306. ies If you are sure the information you supplied to the Edit FDL utility is valid the best values are those that lie along the left hand boundary next to the slash marks If you are not sure that your information is valid you should choose a value that lies more to the right of the slash boundary When you complete the dialog and the Edit FDL utility presents the graph you can make changes to certain attributes of the proposed data file The design is not complete until you specify FD for Finish Design at which point the Edit FDL utility asks a few more questions You then have the opportunity to return to the main menu to view the file attributes that the Edit FDL utility has created Figure 4 3 shows the attributes that you can alter when the Edit FDL utility displays the graph Note that each attribute has a 2 letter mnemonic To alter an attribute you specify the corresponding mnemonic To refresh the display press the Return key To begin the final design phase enter FD 4 12 Creating and Populating Files Creating and Populating Files 4 1 File Creation Characteristics Figure 4 3 Design Mnemonics PV Prologue Version 3 KT Key 0 Type String FD Final Design Phase DK Dup Key 0 Values No KL Key 0 Length 10 KP Key 0 Position 0 RC Data Record Comp 0 KC Data Key Comp 0 IC Index Record Comp 0 RF Record Format Variable RS Mean Record Size 256 LM Load Method Fast Conv IL Initial Load 50000 AR Added Records 5000 Wh
307. ies are not applicable to auto extending an indexed file 3 2 1 3 2 Establishing Auto Extend Default Quantities This section describes how to establish the auto extend default quantities for an RMS file Area and File Default Extension Quantities You can establish a file specific default called the file default extension quantity for all file organizations In the case of an indexed file with multiple areas you can also establish a separate area default extension quantity for each area of the indexed file The following list describes the methods for establishing file default extension quantities and where applicable area default extension quantities e The recommended method is to use the Edit FDL utility to permanently establish file and area default extension quantities when you create or convert a file The Edit FDL utility calculates these quantities using your responses to the script questions and it assigns the file default extension quantity using the FILE EXTENSION attribute For indexed files with multiple areas the Edit FDL utility assigns a default extension quantity to each area using the AREA EXTENSION attribute A subsequent CREATE service or use of the CONVERT utility using an FDL with these EXTENSION attributes permanently sets these defaults For a description of how the Edit FDL utility calculates default extension quantities see Appendix A e One alternative to using the Edit FDL utility is to permanently establis
308. ified command procedure is shown in Example 6 1 Example 6 1 Rooted Directory Syntax ON CONTROL Y THEN GOTO END GOTO ASK RETRY WRITE SYSSOUTPUT Enter a number from 1 to 4 for the type of part WRITE SYSSOUTPUT Select Parts Group 1 COMPUTER 2 TYPEWRITER 3 DESK 4 OTHER 5 END INQUIRE ANS IF ANS GT 5 OR ANS LT 1 THEN GOTO RETRY IF ANS EQ 5 THEN EXIT IF ANS EQ 1 THEN DEFINE TRANS CONCEAL IN DUA29 COMPUTER IF ANS EQ 2 THEN DEFINE TRANS CONCEAL IN DUA29 TYPEWRITER IF ANS EQ 3 THEN DEFINE TRANS CONCEAL IN DUA29 DESK IF ANS EQ 4 THEN DEFINE TRANS CONCEAL IN DUA29 OTHER RUN XYZPROG END EXIT With the enhanced command procedure none of the programs has to be modified recompiled or reassembled relinked or copied to a different directory 6 3 6 Using a Rooted Directory to Extend RMS s Subdirectory Limit On Alpha systems running OpenVMS versions prior to V7 2 and on VAX systems RMS limits the number of subdirectory levels that can be accessed to eight Rooted directory syntax can be used to allow access to subdirectories up to fifteen levels below the volume s MFD RMS allows up to seven levels in the root with eight in the normal non root directory 1 Alpha systems running OpenVMS versions V7 2 and later have a limit of 255 levels DID abbreviation allows access to all subdirectories on a volume regardless of depth 6 18 Advanced Use of File Speci
309. ikely result in an I O operation and caching extra buckets wastes space in your working set In random with temporal locality processing reaccessed records records are processed randomly but the same records may be accessed again You should use multiple small buffers to cache records that are to be reaccessed The bucket size can be small for this type of access because the records near the record currently accessed are not likely to be accessed Caching reaccessed records in large buckets wastes space in memory Multiple buffers allow the previously accessed records to remain in memory for subsequent access In random with spatial locality processing adjacent records records are processed randomly but the next or previous record has a good chance of being accessed You should use a large buffer and bucket size to improve the probability that the next record to be processed is in the same bucket as the record most recently processed One or two buffers should be sufficient If you process your data file with a combination of these patterns you should compromise between the processing strategies An application illustrating both temporal and spatial access uses the first record in the file as a pointer to the last record accessed The program reads the first record to find the location of the next record to be processed processes the record and updates the pointer in the first record Because the application accesses the first record frequ
310. ile For more information about CONVERT and BACKUP see Section 10 4 2 Section 10 5 and Section 10 6 Note If you believe that the software caused the error contact a Compaq support representative Supply the ANALYZE RMS FILE check report a copy of the data file and a description of what was done with the data file If possible also supply a version of the file prior to the corruption and the program or procedure which led to the corruption being able to reproduce the problem is of tremendous value Example 10 1 is a sample Check report of a file with the file specification DISK HERBER CUSTDATA DAT 2 Example 10 1 Using ANALYZE RMS FILE to Create a Check Report Check RMS File Integrity 14 JUN 1993 21 51 47 38 Page 1 DISK HERBER CUSTDATA DAT 2 FILE HEADER File Spec DISK HERBER CUSTDATA DAT 2 File ID 10044 39 1 Owner UIC 011 310 Protection System RWED Owner RWED Group RWE World RWE Creation Date 9 JUN 1993 22 30 24 78 Revision Date 9 JUN 1993 22 30 30 86 Number 4 Expiration Date none specified Backup Date none posted Contiguity Options none Performance Options none Reliability Options none Journaling Enabled none RMS FILE ATTRIBUTES File Organization indexed Record Format variable Record Attributes carriage return Maximum Record Size 80 Blocks Allocated 30 Default Extend Size 2 Bucket Size 1 File Monitoring disabled Global Buffer Count 0 continued
311. ile specification format node device root directory filename type version Advanced Use of File Specifications 6 5 Advanced Use of File Specifications 6 2 Understanding RMS Parsing Note that in the context of a file specification brackets do not imply optional components The only optional components are the node component and the root component RMS isolates the components checks them for proper syntax and copies them to the expanded string If a node name is present RMS attempts to translate it as a logical node name as described previously If a name in the device component is present and the node name is omitted RMS attempts to translate the device name as a logical name After translating a logical name RMS determines whether the translation contains a duplicate component If RMS finds a duplicate component in the primary file specification translation it signals an error Conversely if RMS finds a duplicated component in the default string file specification translation or in the related string file specification translation it ignores discards the duplicate component If the node name is omitted and the device component does not translate successfully RMS treats the name in the device component as a device name If the logical name translates successfully RMS makes several checks and then performs the appropriate task Checks the equivalence string to determine whether it refers to a process permanent fi
312. ile specifications even if wildcard characters were used 5 9 2 Processing Many Files To process many files using a single file specification you always need to use the Parse and Search services to locate the files The application requirements and the directory location of the files generally determine whether one or more search lists wildcard characters or search lists containing wildcard characters are used in the file specification When files must be accessed in nonalphabetical order use a search list To process multiple files using a single file specification invoke the Parse service or its equivalent once to interpret the file specification and to create the file specification pattern to be searched After the file specification is parsed you can invoke the Search service to locate each file that matches the original file specification In some cases you can examine or display the resultant file specification string returned by the Search service to determine if you or the interactive user want to process open the file If you want to list all file specifications that match a particular file specification and let the terminal user choose each file to be processed wildcard characters can be used safely possibly in a search list that contains wildcard characters in one or more of its file specifications To reduce the number of files that the user might choose to process use a search list without wildcard characters or re
313. iles can be shared across a cluster However only computers running OpenVMS Version 7 2 EFT1 or later can mount ODS 5 disks VAX computers running Version 7 2 EFT1 or later can see only files with ODS 2 style names Protected objects Supported Supported Supported Caching of file header blocks file identification slots and extent entries Supported Supported E means execute access Enhanced protection features supported Supported Note Future enhancements to OpenVMS software will be based primarily on structure levels 2 and 5 therefore structure level 1 volumes might be further restricted in the future However Compaq does not intend for ODS 5 to become the default OpenVMS file structure The principal use of ODS 5 will be when OpenVMS is a server for other systems such as Windows NT that have extended file names The default disk structure is Files 11 ODS 2 VAX systems also support Files 11 ODS 1 from earlier operating systems to ensure compatibility among systems Earlier operating systems include the RSX 11M RSX 11D RSX 11M PLUS and Micro RSX systems Introduction 1 5 Introduction 1 2 Disk Concepts 1 2 1 Files 11 On Disk Structure Concepts The term Files 11 On Disk Structure or simply ODS refers to the logical structure given to magnetic disks namely a hierarchical organization of files their data and the directories needed to gain access to them The file
314. ill Quantity 512 Segment Positions Segment Sizes 5 Data Type string Name PART NAME First Data Bucket VBN 13 continued on next page 10 4 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics Example 10 1 Cont Using ANALYZE RMS FILE to Create a Check Report KEY DESCRIPTOR 2 VBN 2 offset X 0066 Next Key Descriptor VBN 2 Offset X 00CC Index Area 5 Level 1 Index Area 5 Data Area 4 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 22 Key Flags 0 KEYSV DUPKEYS 1 1 KEYSV CHGKEYS 0 2 KEY V NULKEYS 0 3 KEYSV IDX COMPR 1 4 KEY V INITIDX 0 6 KEYSV KEY COMPR 1 Key Segments 1 Key Size 10 Minimum Record Size 19 Index Fill Quantity 512 Data Fill Quantity 512 Segment Positions 9 Segment Sizes 10 Data Type string Name SUPPLIER NAME First Data Bucket VBN 19 KEY DESCRIPTOR 3 VBN 2 offset X 00CC Index Area 7 Level 1 Index Area 7 Data Area 6 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 28 Key Flags 0 KEYSV DUPKEYS 1 KEY V CHGKEYS 2 KEYSV NULKEYS 3 KEY V IDX COMPR 4 KEY V INITIDX 6 KEYSV KEY COMPR Key Segments 1 Key Size 10 Minimum Record Size 29 Index Fill Quantity 512 Data Fill Quantity 512 rPOoOrRCOF Segment Positions 19 Segment Sizes 10 Data Type string Name COLOR First Data Bucket VBN 25 The analysis uncovered NO errors ANALYZE RMS FILE OUTPUT CUSTDAT
315. ime to identify those tasks that you routinely perform at your particular site Once you have isolated those tasks you can design command procedures to assist you in performing them For example if you are a system manager or an operator you must frequently perform data integrity tasks such as backing up media You could enter all of the commands parameters and qualifiers required to back up your media each time that you perform the backup operation or you can write a single command procedure containing that set of commands qualifiers and parameters that when executed would also perform the backup operation In order to familiarize yourself with the syntax used to design and execute command procedures see the OpenVMS User s Manual 1 34 Introduction Introduction 1 5 Volume Protection 1 5 Volume Protection The system protects data on disk and tape volumes to make sure that no one accesses the data accidentally or without authorization For volumes the system provides protection at the file directory and volume levels For tape volumes the system provides protection at the volume level only In addition to protecting the data on mounted volumes the system provides device protection coded into the home block of the disks and tapes See Section 1 2 for more information In general you can protect your disk and tape volumes with user identification codes UICs and access control lists ACLs The standard protection mecha
316. indexes provide your program with alternate record processing If you have one or more alternate indexes you can process data records using any of the alternate keys in addition to processing data with the primary key Note that a file with alternate indexes does require additional disk space The alternate index structure is similar to the primary index structure except that instead of containing data records alternate indexes contain secondary index data records SIDRs An SIDR includes an alternate key value from a data record in the primary index and one or more pointers to data records in the primary index SIDRs have pointers to more than one record only if you allow duplicate keys and there are duplicate key values in the database You do not need an SIDR for every data record in the database If a variable length record is not long enough to contain a given alternate key an SIDR is not created For example if you define an alternate key field to be bytes 10 through 20 and you insert a 15 byte record no SIDR is created in that alternate index structure When you create a file you can use null key values to improve performance for programs that use alternate keys When a secondary index has relatively few entries performance may diminish because RMS tries to treat the null entries typically blank keys as duplicates The resultant duplicate key processing is unnecessary and can be avoided by assigning a null key value for the index B
317. information about specifying a logical node name or using any of the file specification formats and their associated syntax rules refer to the OpenVMS User s Manual 5 2 2 The Device Component The device can be identified with either a physical name or a logical name You can terminate a physical device name or a logical device name with a colon and place one or more file specification components directory name file name file type and version after it A logical device name may translate to another logical name a physical device name or a physical device name with additional file specification components The logical name may translate to a combined device name which may be a logical name itself and root name The logical name can be a search list which specifies multiple file locations where the file can be found See Section 5 7 Locating and Naming Files on Disks 5 3 Locating and Naming Files on Disks 5 2 File Specification Components You have to include only the device name when specifying a record oriented device such as a terminal However if you choose to include other file specification components you must follow the naming conventions described previously See also section Section 5 3 The following file specification format is used only for ANSI formatted magnetic tape volumes device directory name quoted ascii a string nn The OpenVMS User s Manual lists the characters from the DEC Multinational chara
318. information about using global buffers refer to the Guide to OpenVMS File Applications In a mixed cluster environment where there may be high contention for specific buckets the Alpha nodes that are using read mode global bucket locking may dominate accesses to write shared files thereby preventing timely access by other nodes With the CONTENTION POLICY keyword qualifier to the SET RMS DEFAULT command you can specify the level of locking fairness at either the process or system level for environments that experience high contention conditions For more information about using the CONTENTION POLICY keyword qualifier refer to the OpenVMS DCL Dictionary File Sharing and Buffering 7 25 8 Record Processing This chapter describes record processing to help you use the run time record operations described in Chapter 9 This chapter provides information about the following subjects e Record operations appropriate to high level languages e Record operations for file organizations e Record environment as it relates to record positioning e Synchronous versus asynchronous record operations 8 1 Record Operations Record operations are performed by OpenVMS RMS hereafter referred to as RMS primary or secondary services Primary services have functional equivalents in high level language record operations whereas secondary services are specific to RMS functions Section 8 2 describes the five primary services For a brief descri
319. ing components and then attempts to locate the file If a node name is present RMS does not process the file specification on the local node Instead it merges any program specified defaults without translation and passes the defaulted untranslated file specification to the file access listener FAL at the remote node the operating system on the remote node interprets it With advanced file parsing a single file specification can be used to locate a single file or multiple files To locate a single file multiple file locations or file names can be searched to ensure that the file is found The multiple file locations or file names can be located in the same or in different directories on different devices on different nodes or a combination thereof Using wildcard characters and search lists you can locate multiple files with a single file specification When a wildcard character or a search list is included in a file specification the application program may need to preprocess the file specification before attempting to locate the file An RMS file service that operates on an unopened file such as the Create service and the Open service performs the following file parsing tasks e Examines a file specification for validity e Translates any logical names present e Applies defaults e Attempts to locate the file If a name block is present the service may also do the following file parsing tasks e Returns the actual complete
320. ing the dot ISO Latin 1 Unicode 32 767 limit version limits are supported Alpha 255 VAX 8 with rooted logical 16 Cannot be an ODS 5 volume 1RSX 11M RSX 11D RSX 11M PLUS and IAS systems do not support subdirectories and alphabetical directory entries 2Prior to OpenVMS Version 7 2 RMS limited directory levels to 8 or 16 1 4 Introduction continued on next page Table 1 4 Cont Comparison of ODS 1 ODS 2 and ODS 5 Levels Introduction 1 2 Disk Concepts Characteristic ODS 1 VAX only ODS 2 ODS 5 OpenVMS Cluster access Disk Disk quotas Multivolume files and volume sets Placement control Caches Clustered allocation Backup home block Protection code E Enhanced protection features for example access control lists RMS journaling Local access only files cannot be shared across a cluster Unprotected objects Not supported Not supported Not supported No caching of file header blocks file identification slots or extent entries Not supported Not supported E means extend for the RSX 11M operating system but is ignored by OpenVMS Not supported Not supported Files can be shared across a cluster Protected objects Supported Supported Supported Caching of file header blocks file identification slots and extent entries Supported Supported E means execute access Enhanced protection features supported Supported F
321. ing file instead of creating the new file The Create service allows you to set file creation characteristics and to create the file directly from your application program For more information about the Create service see the OpenVMS Record Management Services Reference Manual Creating and Populating Files 4 15 Creating and Populating Files 4 2 Creating a File 4 2 2 Using the Create FDL Utility Unlike the Create service using FDL to create a file is a two step process You must first create the FDL file using the Edit FDL utility and then use another RMS utility or your application program to create the data file One of the utilities you can use to create a file is the Create FDL utility CREATE FDL CREATE FDL creates an empty data file from the specifications in an existing FDL file This feature allows you to use the Edit FDL utility to create standard FDL files that describe commonly needed data files and then to use CREATE FDL to create the data files as they are needed For example to create an empty data file called CUSTRECS DAT from the specifications in an FDL file called INDEXED FDL enter the following DCL command CREATE FDL INDEXED FDL CUSTRECS DAT 4 2 3 Using the Convert Utility Another RMS utility that creates an output data file from the specifications in an FDL file is the Convert utility CONVERT However instead of being empty the new output file generally contains data records from the input file un
322. ing in an OpenVMS Cluster Environment 3 7 1 1 Locking Considerations The distributed lock manager allows several users to share files concurrently in an organized manner RMS uses the lock manager to control file access The lock mastering node controls the record and bucket locking for a given file for users on every node of the OpenVMS Cluster Initially it is the first node from which the file is opened However another node may become the lock mastering node when a node either joins or leaves the OpenVMS Cluster The lock mastering node may also change every time the file is opened When another process opens the file provided that the file was closed the node on which that process resides becomes the new lock mastering node for that file Lock requests issued by processes on the lock mastering node incur less cost than lock requests issued from other nodes Conversely the lock mastering node has the additional work of processing lock requests for that file for all other nodes The lock requesting node is any node in the OpenVMS Cluster other than the lock mastering node for a given file RMS locks buckets and records during record operations only if the file is open for shared writing Conversely RMS does no locking during record operations if the file is open for shared read only access or for exclusive access Lock requests for root locks top level or parent locks in an OpenVMS Cluster may be slightly slower than on a singl
323. ing run time option deleting 9 21 inserting 9 18 to 9 20 retrieving 9 14 to 9 18 updating 9 20 to 9 21 Record reference vector See RRV Records 1 1 See also Record formats adding 9 10 9 11 blocking 1 18 contents 2 1 deleting 8 4 9 21 format options 4 34 inserting 8 3 to 8 4 9 18 to 9 20 locating 8 2 to 8 3 locking 9 6 deadlock 7 17 use with update operation 8 3 retrieving 8 2 to 8 3 9 14 to 9 18 sequentially from an indexed file 2 5 updating 8 4 9 20 9 21 Record stream connection option See File opening options Record streams connecting to a file 7 2 definition 7 2 Record transfer mode locate 7 17 move 7 17 RECORD IO attribute 7 3 Related file position option 4 36 Relative file extend size initial value 3 5 maximized value 3 6 Relative files 2 17 advantages of using 2 18 allocating A 1 bucket sizes 3 10 3 16 7 20 A 1 buffering 7 20 to 7 21 deferred write option with 3 12 designing 3 15 to 3 18 disadvantages of using 2 18 examining 10 15 10 16 maximum record size 3 15 optimizing performance 3 15 to 3 18 organization 1 2 record access 8 7 to 8 9 8 14 tuning 3 15 to 3 18 with global buffers 3 17 RELATIVE qualifier 7 21 Relative record number 1 2 3 15 Release service 8 5 Index 12 Remote file access See also File specifications Fortran program example 5 18 Remote nodes 5 3 Rename service 5 22 Repeating characters in co
324. ing to sequential files See Chapter 2 e FDL CONNECT WRITE BEHIND e RMS RAB L ROP RAB V_WBH lIndicates an option that can be specified for each record processing operation For more information see Section 9 3 9 2 4 Record Access Options You can specify the record access for a record stream as sequential random by key or record number or random by RFA See Section 8 1 The selected record access can be changed for each record processing operation These options can be set using the RAB B_RAC field values RAB C_SEQ RAB C_KEY and RAB C_ RFA 9 2 5 Options for Adding Records When adding records to a file consider the open and connection options in the following table Option Description Default extension See Section 9 2 3 quantity Deferred write See Section 9 2 3 End of file After the record stream is connected the record context is positioned to the end of the file e FDL CONNECT END OF FILE e RMS RAB L ROP RAB V EOF Retrieval window See Section 9 2 3 size Revision data The revision date and time and the revision number can be specified to be a value other than the actual revision date and time and revision number when the file is closed These options must be set while the file is open and thus cannot be set using FDL e FDL Does not apply e RMS Revision Date and Time XAB lIndicates an option that can be specified for each record processing operation For more information see
325. ins a program fragment written in VAX MACRO that demonstrates one method of implementing a short pause between attempts to access a locked record Example 7 1 Designing a Pause Between Attempts to Access a Record Get the record Branch on success Record locked error Quit on other errors Pause for One second Quit on error Try again for record 10 SGET RAB INRAB BLBS RO GOT RECORD CMPL RO RMS RLK BNEQ ERROR PUSHAL ONE SECOND CALLS 1 G LIBSWAIT BLBC RO ERROR BRB 10 Se Me Me ne xe xe xe xe For more information about process control techniques see the OpenVMS System Services Reference Manual 7 14 File Sharing and Buffering File Sharing and Buffering 7 2 Record Locking 7 2 3 2 Waiting for Locked Records Another option for handling record locking conflicts is to use the wait if locked option to wait for the locked record to be released When you take this option the accessing service does not return until the record is released or until a specified wait period expires The optional wait period is established using the wait timeout period option in conjunction with the wait if locked option If the specified wait period expires before the requesting service obtains access to the locked record the requesting service discards the request The requesting service returns a completion status indicating that it waited for the locked record but was not granted access within the specified time period RMS TMO If you s
326. int in the file and continues sequentially through the file RMS begins accessing records at the start of the file unless you either specify the starting point explicitly or establish a starting point through a previous operation In the sequential access mode your program issues a series of requests to RMS to retrieve or store succeeding records in a file Before acting on these requests RMS checks the file organization to determine how to proceed The following sections describe how RMS handles sequential access for each of the three file organizations Sequential Access to Sequential Files In a sequential file records are stored adjacent to one other To retrieve a particular record within the file your program must open the file and successively retrieve all records between the current record position and the selected record Figure 2 1 shows a disk surface Each lettered section on the surface represents a record in a sequential file beginning with record A When the program requests sequential access to the file records RMS interprets each request in the context of the file s organization Because this particular file is sequential RMS complies with each request except for the first request by accessing the record immediately following the previously accessed record For example after RMS accesses record A it updates the current record position to record B in anticipation of the next request Figure 2 1 Sequential Access to
327. ion Function Create if Creates the file only if the directory does not contain a file with the same name If a file with the same name exists in the directory RMS opens the existing file instead of creating a new file e FDL FILE CREATE IF e RMS FABSL FOP FAB V CIF Maximize version Creates the file with the specified version number or a version number one greater than a file of the same name in that directory e FDL FILE MAXIMIZE VERSION e RMS FABS L FOP FAB V_MXV Supersede version Supersedes the file with the same name type and version number in the current directory e FDL FILE SUPERSEDE e RMS FAB L_FOP FAB V_SUP Creating and Populating Files 4 31 Creating and Populating Files 4 6 Summary of File Creation Options Name of Option Function Temporary Temporary delete Creates a temporary file which has no directory entry that is retained when the file is closed The file can be accessed only if its internal file identifier is known requires the use of a name block Name blocks provide additional fields for extended file specifications e FDL FILE DIRECTORY ENTRY e RMS FAB L_FOP FAB V_TMP Creates a temporary file which has no directory entry marked for deletion The file is deleted automatically when the file is closed e FDL FILE TEMPORARY e RMS FAB L_FOP FAB V_TMD 4 6 2 File Characteristics The creation time options that define file characteristics are described in the
328. ion when creating a file e FDL FILE MT CURRENT POSITION e RMS FAB L_FOP FAB V POS Directs that the tape volume be rewound before it opens or creates the file The rewind on open option overrides the current position option e FDL FILE MT OPEN REWIND e RMS FAB L_FOP FAB V_RWO Directs that the tape volume be rewound before it closes the file e FDL FILE MT_CLOSE_REWIND e RMS FAB L_FOP FAB V_RWC 9 2 10 Options for Nonstandard File Processing The following table lists the run time file open options that apply to nonstandard file processing Option Description Non file structured User file open Use this option when you want to process data from volumes created on systems other than Compaq systems e FDL FILE NON_FILE_STRUCTURED e RMS FAB L_FOP FAB V_NFS Use this option if you want to use RMS only to open the file and you intend to access the contents of the file using Queue I O Request system service calls The system returns the I O channel number in the FAB L_STV field e FDL FILE USER FILE OPEN e RMS FAB L_FOP FAB V UFO 9 3 Summary of Record Operation Options This section briefly describes the options associated with the record retrieval services Find and Get the record insertion service Put the record modification service Update and the record deletion service Delete 9 14 Run Time Options Run Time Options 9 3 Summary of Record Operation Options 9 3 1 Record Retrieva
329. iptor path contains the primary key structures and data records and any secondary key structures Figure 10 4 shows the structure following the area descriptor path Figure 10 4 Area Descriptor Path File Header File Attributes Area Key Descriptors Descriptor ZK 0329 GE Maintaining Files 10 17 Maintaining Files 10 1 Viewing File Characteristics Example 10 5 shows an examination of an area descriptor path from the PROLOG level Example 10 5 Examining an Area Descriptor Path ANALYZE DOWN AREA AREA DESCRIPTOR 0 VBN 3 offset X 0000 Bucket Size 1 Alignment AREASC NONE Alignment Flags 0 AREASV HARD 0 1 AREA V_ONC 0 5 AREASV CBT 0 7 AREASV CTG 0 Current Extent Start 1 Blocks 9 Used 7 Next 8 Default Extend Quantity 0 Figure 10 5 shows the structure following the key descriptor path As shown in the figure you can branch directly to the DATA BUCKET or you can branch to the INDEX ROOT BUCKET to begin examination of the index structure eventually reaching the DATA BUCKET structure Depending on whether you are examining the primary index structure or one of the alternate index structures there is a difference in the contents of the record structure The PRIMARY RECORD structure contains the actual data records the ALTERNATE RECORD structures contain secondary index data records SIDRs 10 18 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics
330. is allows records to be deleted rapidly but it may degrade the performance of processes that read the file later e FDL CONNECT FAST DELETE e RMS RAB L ROP RAB V_FDL Returns the first record with a key value equal to the key you specified when locating or reading records If RMS does not find a record with an equal key value it returns the record with the next higher key value when ascending sort order is specified When descending sort order is specified RMS returns the next record with the next lower key value e FDL CONNECT KEY_GREATER_EQUAL e RMS RAB L_ ROP RAB V_EQNXT Returns the record with the next higher key value when you specify ascending sort order when locating or reading records When you specify descending sort order RMS returns the next record with the next lower key value If you do not specify either this option or the equal or next key option RMS tries for a key match e FDL CONNECT KEY_GREATER_THAN e RMS RAB L_ROP RAB V_NXT lIndicates an option that can be specified for each record processing operation For more information see Section 9 3 9 12 Run Time Options Run Time Options 9 2 Options Related to Opening and Closing Files Option Description Key of reference Permits you to specify which key to use for the current record stream when you process an indexed file with multiple keys e FDL CONNECT KEY OF REFERENCE e RMS RABS B KRF Key buffer Specifies key buffer that must contai
331. is the optimized version of the original FDL file Conversion is the process of applying the optimized FDL file to the original data file You use the Convert utility to do this using a command with the following syntax CONVERT FDL optimized fdl file original data file new data file 10 4 Making a File Contiguous If your file has been used for some time or if it is extremely volatile the numerous deletions and insertions of records may have caused the optimal design of the file to deteriorate For example numerous extensions will degrade performance by causing window turn operations In indexed files deletions can cause empty but unusable buckets to accumulate If additions or insertions to a file cause too many extensions the file s performance will also deteriorate To improve performance you could increase the file s window size but this uses an expensive system resource and at some point may itself hurt performance A better method is to make the file contiguous again This section presents techniques for cleaning up your files These techniques include using the Copy utility the Convert utility and the Convert Reclaim utility 10 4 1 Using the Copy Utility You can use the COPY command with the CONTIGUOUS qualifier to copy the file creating a new contiguous version The CONTIGUOUS qualifier can be used only on an output file To use the COPY command with the CONTIGUOUS qualifier use the following command syntax
332. isplays the Edit FDL utility commands you can use The ADD command displays the Legal Primary Attributes menu The Legal Primary Attributes menu shows the primary attributes You can either add a new primary attribute or add a secondary attribute to an existing primary attribute Initially the FILE primary attribute is the default Run Time Options 9 3 Run Time Options 9 1 Specifying Run Time Options Q The selection of the CONNECT primary attribute displays the Legal CONNECT Secondary Attributes You could similarly select the ACCESS FILE or SHARING options instead of the CONNECT primary attribute to display the Legal Secondary Attributes for the selected primary attribute FDL file WRITE yes chosen e o 88 6 OQ This menu shows all the CONNECT secondary attributes you can add to your Select the proper CONNECT secondary attribute in this case LOCK ON The Edit FDL utility verifies that you have selected the secondary attribute Enter the value that you want the secondary attribute to have for instance The Edit FDL utility verifies the value for the secondary attribute you have Return to the main menu If you choose to add another secondary attribute you will notice that CONNECT is now the default The FDL file containing the CONNECT primary attribute with the WRITE BEHIND secondary attribute is shown in the following example IDENT 19 JUL 1994 14 57 37 SYSTEM SOURCE FILE ORGANIZATION RE
333. ity The performance associated with the previous algorithm effectively limited the maximum number of global buffers on large shared files With this change you may increase the number of global buffers on these files to the full limit of 32 767 to fully exploit large memory systems Concurrent Access RMS synchronizes access to the global section that is used for RMS global buffers by using inline atomic instruction sequences rather than distributive locking This change allows more concurrent access to the section particularly on symmetric multiprocessing machines SMP Greater scalability benefits those who wish to use very large global buffer counts Concurrent access to the global section helps any application using global buffers where contention on the global section itself is a bottleneck Note By increasing the number of global buffers on specific files you may need to increase the size of some of the system resources In particular you may need to increase the sysgen parameters GBLPAGES GBLPAGFILE or GBLSECTIONS In addition you may need to increase the process working set size and the page file quota 7 24 File Sharing and Buffering File Sharing and Buffering 7 3 Local and Shared Buffering Techniques Read Mode Bucket Locking Alpha Only RMS reduces locking for shared access to global buffers and improves performance with its implementation of read mode global bucket locking which has the following functiona
334. ization and use of your data files The recommended way to determine the optimum number of buffers for your application is to use the Edit FDL utility The number of I O buffers is a run time parameter you set with the FDL editor by adding the CONNECT secondary attribute MULTIBUFFER_COUNT to the definition file See Chapter 9 With a low level language you can set the value directly into the RAB B_MBF field of the record access block or you can set the count using the XAB MULTIBUFFER COUNT XABITM if you want to specify more than 127 buffers Alternatively the number of buffers may be specified for a process using the DCL command SET RMS_DEFAULT BUFFER_COUNT n where the variable n represents the desired number of buffers With this command you may set distinct values for your sequential relative and indexed files using the appropriate file organization qualifier If you omit the file organization qualifier sequential organization is assumed To examine the current settings for the process and system default multibuffer count use the DCL command SHOW RMS DEFAULT If none of the above methods is used RMS uses the system wide default value established by the system manager If the system wide default is either omitted or is set to 0 RMS uses a value of 1 for sequential and relative files and a value of 2 for indexed files Performance Considerations 3 11 Performance Considerations 3 2 Tuning For more details about using multiple
335. k field FAB B_BKS or XAB B_BKZ as described in Chapter 2 When accessing indexed files it is important to remember that the index portion of the file must be read by RMS to locate the desired record The algorithm used by RMS places a higher priority for the higher level buckets of the index in the buffer cache Thus the highest levels of the index remain in the buffer cache while the buffers that may have contained the actual data buckets and the lower level index buckets are reused to contain other buckets That is the buffers that are reused first contain either data or lower level index buckets which are the first to be discarded from the buffer cache When accessing indexed files the number of local buffers CONNECT MULTIBUFFER COUNT is specified at run time and recommended values can vary greatly for different application programs When records are processed randomly use as many buffers as your process working set can support to cache additional index buckets When records are accessed sequentially even after locating the first record randomly use a small multibuffer count such as the default of 2 buffers File Sharing and Buffering 7 21 File Sharing and Buffering 7 3 Local and Shared Buffering Techniques Many application programs access files using a mixture of completely random and completely sequential processing For such application programs a compromise of the above number of buffers is recommended When adding rec
336. ket VBN 0 Current Extent Start 16 Blocks 3 Used 1 Next 17 Default Extend Quantity 1 Total Allocation 3 STATISTICS FOR AREA 3 Count of Reclaimed Blocks 0 AREA DESCRIPTOR 4 VBN 3 offset X 0100 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 19 Blocks 3 Used 1 Next 20 Default Extend Quantity 1 Total Allocation 3 STATISTICS FOR AREA 4 Count of Reclaimed Blocks 0 AREA DESCRIPTOR 5 VBN 3 offset X 0140 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 22 Blocks 3 Used 1 Next 23 Default Extend Quantity 1 Total Allocation 3 STATISTICS FOR AREA 5 Count of Reclaimed Blocks 0 AREA DESCRIPTOR 6 VBN 3 offset X 0180 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 25 Blocks 3 Used 1 Next 26 Default Extend Quantity 1 Total Allocation 3 STATISTICS FOR AREA 6 Count of Reclaimed Blocks 0 continued on next page Maintaining Files 10 7 Maintaining Files 10 1 Viewing File Characteristics Example 10 2 Cont Using ANALYZE RMS FILE to Create a Statistics Report AREA DESCRIPTOR 7 VBN 3 offset X 01C0 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 28 Blocks 3 Used 1 Next Default Extend Quantity 1 Total Allocation 3 STATISTICS FOR AREA 7 Count of Reclaimed Blocks 0 KEY DESCRIPTOR 0 VBN 1 offset X 0000 Next Key Descriptor VBN 2 Offset X 0000 Index Area 1 Level 1 I
337. l Options The Find and Get services or the equivalent language statements can be used to locate and retrieve a record The options associated with the Find and Get services are summarized in the following table These options can be set for each Find or Get service if the program can access the appropriate RAB control block fields The RAB control block fields are preset by connect time values or defaults and as a result of previous service calls Option Description Asynchronous record Specifies that record I O for this record stream is done processing asynchronously e FDL CONNECT ASYNCHRONOUS e RMS RAB L_ROP RAB V_ASY Do not lock record Directs RMS not to lock the record for ensuing operations e FDL CONNECT NOLOCK e RMS RAB L_ROP RAB V NLK Key buffer Specifies key buffer that must contain the desired record s key when you are locating or reading records randomly e FDL None e RMS RAB L_KBF Key equal or next Returns the first record with a key value equal to the specified key when you are locating or reading records If RMS does not find a record with an equal key value it returns the record with the next higher key value when you specify ascending sort order When you specify descending sort order RMS returns the record with the next lower key value e FDL CONNECT KEY GREATER EQUAL e RMS RAB L_ROP RAB V EQNXT Next key Returns the record with the next higher key value when you specify ascending sort order
338. large indexed file yet the default number of buffers RMS provides is only two The CONNECT secondary attribute MULTIBUFFER COUNT establishes the number of local buffers but the FILE secondary attribute GLOBAL BUFFER COUNT FAB field FAB W_GBC specifies the number of global buffers as described in Section 7 3 6 Often the best way to achieve optimum buffering for a particular application program is to use combinations of buffer sizes and numbers of buffers One approach is to time each combination and measure the number of I O operations Then consider the amount of memory used before you choose the one that improved application program performance the most With buffering the goal is to use a buffer size and number of buffers that improves application program performance without exhausting the virtual memory resources of your process or system Keep in mind the trade offs between file I O performance and exhausting memory resources The buffers used by a process are charged against the process s working set You should avoid allocating so many buffers that the CPU spends excessive processing time paging and swapping For performance critical application programs consider increasing the size of the process working set and adding additional memory The system manager should monitor the paging and swapping activity of the application program s process and selected other processes to avoid improving the performance of the target application pro
339. ld have to be updated to use the interface extensions To provide extended capabilities such as access to deep directories to applications that continue to use the older interface RMS supports the generation and acceptance of file specifications with an abbreviated form of root or directory specification known as a DID for Directory ID abbreviation Note The DID abbreviation is used in file specifications and should not be confused with the numeric DID field of the NAM block The DID is an alternate form of subdirectory specification that is not relative to the MFD It takes the form for ODS 2 and ODS 5 disks of three decimal numbers separated by commas and can be used in the MFD position in a root or directory component specification Examples of valid root and directory components with DIDs are as follow DKA200 24 42 0 DKA200 1223 4 0 a DKA200 134 59 0 DKA200 1223 4 0 134 59 0 Advanced Use of File Specifications 6 19 Advanced Use of File Specifications 6 4 DID Abbreviated Directories Alpha Only A DID can also be used in place of a subdirectory in a root or directory component but subdirectories located to its left in the specification above it in the directory tree are elided by RMS as shown in the following example SET PROCESS PARSE STYLE EXTENDED SWRITE SYS OUTPUT FSPARSE DKA200 system test 134 59 0 DKA200 134 59 0 WRITE SYS OUTPUT F PARSE DKA200 system test
340. lde first file name character 5 10 TIMEOUT PERIOD attribute 7 14 TOP command 10 11 Track 1 12 3 16 Trailer labels 1 22 1 34 TRANSLATION ATTRIBUTES qualifier 5 20 6 14 Tree structures of indexed files 10 17 of relative files 10 15 of sequential files 10 12 TRUNCATE attribute 7 3 Truncate on put option access requirement 7 7 Truncate service 8 4 8 5 effect on next record position 8 17 Truncating a file access limitation 3 9 Truncation errors 3 9 Tuning 3 3 10 24 indexed files 3 18 relative files 3 15 sequential files 3 13 C IC based protection 4 26 ICs user identification codes 1 35 JNDEFINED format 2 13 P command 10 11 JPDATE attribute 7 3 7 4 pdate if option 8 3 to 8 4 pdate operation 3 13 pdate service 8 1 8 4 high level language equivalents 8 1 run time options 9 20 to 9 21 JPDATE IF attribute 8 7 ppercase letters 5 7 ser buffers address 9 17 size 9 18 User identification codes See UICs USER FILE OPEN attribute 7 4 USER INTERLOCK attribute 7 4 7 6 V qaqqcq SREE acg Variable length records 1 32 with D format 2 10 with V LSB format 2 9 with V MSB format 2 9 Variable with fixed length control field See VFC record format VAX BASIC See BASIC See BASIC USEROPEN routine VAX COBOL See COBOL VAX Fortran See Fortran VAX Pascal See Pascal Version numbers 1 29 VFC records format 1 2
341. le If the equivalence string refers to a process permanent file defaults are not needed so RMS stops processing the file specification and copies the logical name to the expanded string Process permanent files are described in Section 6 6 Checks the equivalence string to determine whether the logical name is a concealed device logical name If the logical name is a concealed device logical name and if no concealed device logical names have been encountered previously in the device file specification the source string is used as the device name Restarts the translation operation using the equivalence string as input if the equivalence string does not contain a process permanent file and does not have the terminal attribute If a node name is present RMS passes the entire file specification without the node name to the remote node for interpretation using the DECnet data access protocol DAP to communicate with the DECnet file access listener FAL at the remote node The logical name translation procedure reveals two conventions First if the file specification has been parsed previously by an RMS file service it uses the open by name block option to save processing time Second a logical device name must be placed at the beginning of a file specification unless it is preceded by a node name that indicates the node where the logical name should be translated 6 2 3 Special Parsing Conventions Additional parsing conve
342. le and Block I O Accessed File Extend Size The auto extend size used for sequential files is also used for all file organizations when accessed by block I O The extend size is selected from the following ordered list of default extension quantities Generally if a default extension quantity does not exist it is set to zero RMS processes this list until it finds a nonzero value e File default extension quantity e Process default extension quantity e System default extension quantity Note that if the selected value from this list is any value but the file default extension quantity the selected value is maximized against the volume default extension quantity In the case of a device full error RMS retries the extend requesting the minimum number of blocks to satisfy the user s write request No retries are done if a disk quota is exceeded a quota exceeded error is returned RMS Supplies a Minimal Extend Size RMS supplies a minimal extend size that is the smaller of twice the buffer size or 256 The buffer size in this calculation depends on the type of file access If the file is a sequential file that is opened for record I O access RMS uses the multiblock count If the file is opened for block I O access regardless of organization RMS uses the size of the user buffer supplied by the application to the WRITE service Relative File Extend Size A relative file can be viewed as an accessible series of fixed sized cells or records
343. le attributes and data from the RMS extension and block mode file attributes and data from the file Example 4 7 illustrates a BLISS 32 program that accesses a tagged file from an application program that does not use an RMS extension Creating and Populating Files 4 23 Creating and Populating Files 4 3 Creating and Accessing Tagged Files Example 4 7 Accessing a Tagged File MODULE TYPESMAIN IDENT X 1l MAIN MAIN ADDRESSING MODE EXTERNAL GENERAL BEGIN FORWARD ROUTINE MAIN NOVALUE Main routine INCLUDE FILES LIBRARY SYSSLIBRARY STARLET OWN NAM SNAM ITEM BUFF BLOCK XABSK SEMANTICS MAX LEN BYTE RETLEN T 7 FAB XABITM xabitm itemlist SITMLST UPLIT ITMCOD XABS STORED SEMANTICS BUFADR ITEM BUFF BUFSIZ XABSK SEMANTICS MAX LEN RETLEN RETLEN 7 mode SENSEMODE RAB ITEMLIST BLOCK ITM S ITEM 4 BYTE RAB XABITM SXABITM itemlist RAB ITEMLIST mode SETMODE FAB SFAB fnm TAGGED FILE TEST nam NAM fac lt GET PUT UPD gt xab FAB XABITM REC BLOCK 512 BYTE STATUS RAB SRAB xab RAB XABITM fab FAB rsz 512 rbf REC usz 512 ubf REC DESC BLOCK 8 BYTE INITIAL 0 ROUTINE MAIN NOVALUE BEGIN STATUS SOPEN FAB FAB IF NOT STATUS THEN SIGNAL STATUS RAB ITEMLIST ITM W BUFSIZ RETLEN RAB ITEMLIST ITM L BUFADR ITEM BUFF RAB ITEMLIST ITM W ITMCOD STATUS CONNECT RAB RA
344. length of a file specification string is 255 characters including all separator characters The following table lists the length limits for each of the component parts of a file specification Note that although the collective limit exceeds 255 characters the overriding limitation is on the length of the file specification Component Number of Characters Node Up to 59 bytes including an access control string physical node names are up to 6 bytes logical node names are up to 15 bytes Device Up to 15 bytes for a physical device name up to 64 bytes for a logical device name Root Up to 39 bytes for each root name Directory Up to 39 bytes for each subdirectory and subdirectory name Filename Up to 39 bytes Type Up to 39 bytes Version C to 5 digits which optionally may be preceded by a hyphen 5 12 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 4 File Specification and Component Length Limits 5 4 2 ODS 5 on Alpha Systems The maximum length of a file specification string is 4095 characters including all delimiters The following table lists the length limits for each of the component parts of a file specification Component Number of Characters Node Up to 59 bytes including an access control string physical node names are up to 6 bytes logical node names are up to 15 bytes Device Up to 15 bytes for a physical device name up to 64 bytes for a logical device name Root The sum of a
345. les in which the input file specification can provide default components for the output file specification The final default mechanism which is not provided by the program is for RMS to use the process default device and directory Table 6 1 describes the defaults that RMS uses to produce a complete file specification when these components device and directory cannot be obtained from the primary default and related file specifications Advanced Use of File Specifications 6 1 Advanced Use of File Specifications 6 1 How RMS Applies Defaults Table 6 1 File Specification Defaults File Specification Description Primary If the device field is a logical name RMS translates the logical device name to its component parts The resulting device name may be a physical device name a process permanent file name or another logical name Default If the device field is a logical name RMS translates it before defaults are applied If any of the fields in the file specification from the previous step are missing they are supplied from the corresponding fields in the translated default file specification where applicable Related If the device field is a logical name RMS translates it and applies the default values before it uses the related file specification to add missing component fields If fields contain wildcard characters the wildcard characters remain in the fields When RMS uses the related file specification to complete
346. less the input file was also empty Note that the Convert utility processes relative files by sequentially reading records from the input file then writing them to the output file As a result the relative record numbers RRN change when the input file contains deleted or unused records If you want to use CONVERT to change the characteristics of a particular file you can use a DCL command of the following form CONVERT FDL fdl file input file output file The CONVERT FDL command creates a new file named by the output file parameter and assigns the new file the characteristics specified in the FDL file For more information about populating data files with CONVERT see Section 4 5 4 2 4 Using the FDLSCREATE Routine You can also create data files according to your specifications with the FDL CREATE routine FDL CREATE is the FDL routine most likely to be called from a high level language It creates a file from an FDL specification and then closes the file The FDL CREATE routine performs the same function as the Create FDL utility but it allows you to create data files from your application However it allows you to use only the creation time features of RMS Example 4 4 shows how to call the FDL CREATE routine from a Fortran program 4 16 Creating and Populating Files Creating and Populating Files 4 2 Creating a File Example 4 4 Using the FDL CREATE Routine in a Fortran Program This program calls the FDLSCREATE routi
347. list as an array with the number of statistics that requested There are four number of files number of records exception records and good records in that order INTEGER 4 STATSBLK 5 4 0 0 0 0 Declare the file names CHARACTER IN FILE 7 SEQ DAT 1 OUT FILE 12 CUSTDATA DAT 1 FDL FILE 11 INDEXED FDL Call the routines in their required order STATUS CONV PASS FILES IN FILE OUT FILE FDL FILE IF NOT STATUS CALL LIBSSTOP VAL STATUS STATUS CONVSPASS OPTIONS OPTIONS IF NOT STATUS CALL LIBSSTOP VAL STATUS STATUS CONVSCONVERT STATSBLK IF NOT STATUS CALL LIBSSTOP VAL STATUS Display the statistics information WRITE 6 1000 STATSBLK I I 2 5 FORMAT 1X Number of files processed 15 1 lX Number of records 15 1 1X Number of exception records I5 1 lX Number of valid records I5 END 4 28 Creating and Populating Files Creating and Populating Files 4 5 Populating a File Example 4 9 shows how to call the CONVERT routines from a COBOL program Example 4 9 Using the CONVERT Routines in a COBOL Program 3 ee he He O3 O9 o eee ee He HSE EH HH SE He HH HE CONV COB This program calls the routines that perform the functions of the Convert utility It creates an indexed output file named CUSTDATA DAT from the Specifications in an FDL file named INDEXED FDL The program then loads CUSTDATA DAT with records from the sequential file SE
348. lity e Allows concurrent read access to the global buffers Accesses are no longer serialized waiting to acquire an exclusive lock for a read access e Caches the read mode lock as a system lock which is retained over accesses and only lowered to null when the lock is blocking an exclusive write request This functionality significantly reduces both local and remote lock request traffic the number of ENQ and DEQ system service calls as well as associated IPL 8 spinlock activity and System Communications Services SCS messages for a cluster e Does not increase lock resource names or the number of active system or process locks on the system e Is functionally compatible in mixed version clusters that include both Alpha and VAX computers This functionality applies to read operations using the GET and FIND services for all three file organizations sequential relative and indexed It also applies to a write operation using the PUT service for the read accesses used for index buckets the first time through an index tree for the write You do not need to change existing applications to implement the read only global bucket locks However global buffers must be set on a data file to take advantage of the enhancement Use the following DCL command where n is the number of buffers SET FILE GLOBAL BUFFER n filename For information about specifying the number of buffers refer to the OpenVMS DCL Dictionary For general
349. ll of the characters in all of the subdirectory names not counting the brackets or the delimiter periods should not exceed 512 compound characters In addition individual subdirectory names have the same constraints as those for the file name type and version components taking into account the fact that subdirectories are stored on disk in the form of files with the names subdirectory DIR 1 Directory The sum of all of the characters in all of the subdirectory names not counting the brackets or the delimiter periods should not exceed 512 compound characters In addition individual subdirectory names have the same constraints as those for the file name type and version components taking into account the fact that subdirectories are stored on disk in the form of files with the names subdirectory DIR 1 File Name Up to 255 bytes subject to the constraint on the sum of the lengths of the file name the file type and the file version as described below Type Up to 255 bytes subject to the constraint on the sum of the lengths of the file name the file type and the file version as described below Version Up to 5 digits which optionally may be preceded by a hyphen plus the delimiter subject to the constraint on the sum of the lengths of the file name the file type and the file version as described below RMS supports file names for which the sum of the lengths of the file name the file type and the fil
350. lock in the index file normally next to the bootstrap block that identifies the volume as a Files 11 On Disk Structure volume and provides specific information about the volume such as volume label and protection index The structure that allows retrieval of records in an indexed file by key value See also key indexed file index file A file on each Files 11 On Disk Structure volume that provides the means for identification and initial access to the volume Contains the access information for all files including itself on the volume bootstrap block home block file headers Glossary 3 Glossary 4 indexed file organization A file organization that allows random retrieval of records by key value and sequential retrieval of records in sorted order by key value See also key indexed file interrecord gap IRG An interval of blank space between data records on the recording surface of a magnetic tape The IRG enables the tape unit to decelerate stop if necessary and accelerate between record operations l O buffer A buffer used for performing input output operations IRG See interrecord gap key indexed file A character string a packed decimal number a 2 or 4 byte unsigned binary number or a 2 or 4 byte signed integer within each data record in an indexed file You define the length and location within the records RMS uses the key to build an index See also primary key alternate key and random acc
351. ly less on wildcard characters For example to locate all files in a directory tree on 5 28 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 9 Using One File Specification to Locate Many Files different devices with a file type of DAT you could define the search list TREE as follows DEFINE TREE DISK1 MYDIR DISK2 MYDIR The primary file specification that would be used for the Parse service would be TREE DAT A great number of files might match this For applications that will need to locate certain files search lists with limited use of wildcard characters might be needed Consider a file that contains a prefix of RESULTS followed by the date for which the data applies You could use the file name RESULTS JUN DAT to locate a record that was entered in the month of June by executing a Search service followed by an Open service for each file reading all records until the correct one is found and invoking the Close service after processing each file A search list should be used when a predefined group of files is processed by a program that is not intended to be interactive Using a search list is particularly desirable if the files have unrelated file names or if they are located on different directories or devices A search list also minimizes processing time by searching for a definite group of files 5 9 3 Processing One or Many Files For general purpose applications when the user enters a
352. ly time and at run time using the same control block The assembly time macros are placed in a data section of the program the run time macros are placed in a code section of the program Using VAX MACRO control blocks are allocated within the program space at assembly time and it may not be necessary to use the run time macros because the program can move values to the control block fields using the instruction set Other languages however may not allocate the control blocks within program storage If your program has access to the starting location of the control block a record access block for instance the VAX MACRO assembly time control block macro or the corresponding symbol definition DEF macro provides your program with certain symbolic offsets symbols that can be used to locate and identify the various fields in the control block Some languages provide a means of making these symbols available to your program For additional information about using the control block macros and control block fields refer to the OpenVMS Record Management Services Reference Manual 9 2 Options Related to Opening and Closing Files Before your program can access the records in a file it must open the file and connect a record stream When it finishes processing records and no longer requires access to that file your program should close the file The options available for opening files connecting record streams and closing files include file
353. ly to block I O processing and to record processing for nonshared sequential files residing on disk devices Two important options for shared files are the file access and file sharing options These options specify the type of record access that the sharing processes can perform They are specified by the FDL attributes ACCESS and SHARING and the FAB fields identified by the symbolic offsets FAB B_FAC and FAB B_SHR When creating or opening a file RMS compares the values of these fields to determine whether or not the requesting process may have access to the file In this manual the term accessor refers either to a process that accesses a file or a record stream that accesses a record The first process to access a file determines which operations other accessors can perform on the file which in practice determines whether or not subsequent users are allowed to access the file For example if your process requests a certain type of access that the first 7 2 File Sharing and Buffering File Sharing and Buffering 7 1 File Accessing accessor since the file was last closed has disallowed your process cannot access the file When choosing the access other processes may have to the file you can specify the type of file sharing to be used and indicate whether or not other processors can access the file simultaneously In an OpenVMS Cluster environment processes can access shared files on the same or different nodes See Section 3 7
354. ly to record processing and to opening and closing a file can usually be preset by file open and record stream connection values Some options can be selected after you open a file and connect a record stream Note that run time options discussed in previous sections are only summarized in this chapter Most of the material in this chapter relates to options not previously described in this document 9 1 Specifying Run Time Options This section describes the way you use the Edit FDL utility to specify run time options that are available to your program through the FDL PARSE and FDL RELEASE routines It also describes the use of language statements and OpenVMS RMS hereafter referred to as RMS to specify control block values You select RMS options by setting appropriate values in RMS control blocks within the data portion of your program In many cases you can select these values by using keywords available to you in the language OPEN statement for your application or by taking suitable default values The values may be selected using keywords in your record and file description statements or they may be selected directly within the OPEN statement If your application is written in a language that does not provide keywords for the various features you can usually select the options using the File Definition Language FDL Predefined FDL attributes can be supplied to your program at run time using the FDL PARSE routine This routine also
355. m to the ISO 9660 standard at implementation level 2 and interchange level 3 This section describes how Files 11 C D resolves incompatibilities between the OpenVMS file system and the ISO 9660 standard The incompatibilities include the following e The ISO 9660 requirement for handling blocks that exceed 512 bytes e Partial extents e Interleaved data e Undefined record formats Logical Blocks Greater Than 512 Bytes OpenVMS device drivers are designed to handle files made up of 512 byte blocks that are uniquely addressable The ISO 9660 standard supports logical blocks that are greater than 512 bytes The Files 11 C D ACP solves this incompatibility by converting ISO 9660 logical block size requests into OpenVMS block size requests at the file system level Partial Data Blocks Any logical block in an ISO 9660 file extent may be partially filled with data RMS assumes that all file blocks are filled with data with the possible exception of the final block When RMS finds a data block that is not filled it attempts to start end of file processing To prevent RMS from misinterpreting a partially filled block as the final file block the Files 11 C D ACP uses I O operations that combine adjacent ISO 9660 logical blocks into full 512 byte logical blocks Interleaving Interleaving is used to gain efficiency in accessing information by storing sequential information on separate tracks The OpenVMS file system is not natively compatible wit
356. magnetic tape format for this configuration Introduction Introduction 1 3 Magnetic Tape Concepts Figure 1 8 Single File on Multiple Tape Volumes eer voL HDR1 HDR2 HORS M First Section of First File Continuation Volume e erm voL Hort HDR2 HORS M Second Section of File When the driver encounters an EOT marker during a write operation the MTAACP writes the appropriate trailer labels and performs a volume switch if necessary ZK 0347 GE Figure 1 9 Multifile Single Volume Configuration e voL HR HDR2 HORS i EOF1 EOF2 Eora mu on HDR2 HDR3 Second File ZK 0345 GE TM Introduction 1 25 Introduction 1 3 Magnetic Tape Concepts Figure 1 10 Multifile Multivolume Configuration First Volume e er voL HDR1 HDR2 HORS m First File When the driver encounters an EOT marker during a write operation the MTAACP writes the appropriate trailer labels and performs a volume switch if necessary ZK 0348 GE 1 26 Introduction Introduction 1 3 Magnetic Tape Concepts 1 3 1 5 Volume Labels The sections that follow describe the first volume VOL1 and second volume VOL2 labels 1 3 1 5 1 VOL1 Label The 80 character volume label VOL 1 is the first label written on an ANSI magnetic tape volume It defines the label type name and owner of the volume Although there are many fields in a VOLI label this section describes only those fields
357. mand BLOCKSIZE qualifier 1 32 RECORDSIZE qualifier 1 33 window size and 9 8 MTACP magnetic tape ancillary control process 1 20 MT BLOCK SIZE attribute 4 32 MT PROTECTION attribute 4 33 Multiblocks 3 13 count for calculating auto extend 3 5 count to establish global buffer size in shared sequential file operations 7 24 definition 3 10 option 2 1 restriction for use 3 10 MULTIBLOCK COUNT attribute 7 20 Multibuffer count 3 14 3 27 MULTIBUFFER COUNT attribute for sequential file 7 20 record access type and 7 21 Multifile multivolume configuration 1 24 Multiple areas advantages 3 24 Multiple files on a single tape volume 1 24 Multiple File Versions 5 7 Multiple services for retrieving records 8 3 MULTISTREAM attribute 7 4 N NAMS B RSS field NAM L_ESA field NAM L_RLF field NAM L_RSA field NAM T DVI field 6 5 NAM W_DID field 6 5 NAM W_FID field 6 5 NAMDEF macro 5 23 Name blocks See NAMs NAML L FNB field 6 11 NAML L LONG RESULT field 6 8 6 8 9 7 6 8 8 4 3 3 D2AD Index 9 NAML L LONG RESULT ALLOC field 6 8 NAML L RLF field 6 8 NAMLs long name blocks 5 21 NAMs name blocks 5 25 address field 5 22 resulting file specification and 5 21 search list in 5 22 Search service and wildcards 5 21 support by FDL 5 23 support by languages 5 23 wildcard character in 5 22 NEXT command 10 11 to 10 15 Next key optio
358. mat each record occupies the same amount of space in the file and the specified length must be able to accommodate the longest record in the file If any record fields are not used your program must be able to detect them and provide appropriate error processing If you specify the block span option records are limited to 512 bytes 2 1 2 2 Variable Length Record Format When you specify the variable length record format each record is as long as the data within it requires except that all records are padded to an even number of bytes The number of bytes is encoded in a 2 byte count field prefixed to the record The field may be coded in either LSB least significant byte or MSB most significant byte format The count field for each record begins on an even byte boundary and contains the number of bytes in the record RMS builds the count field from information in your program and treats it separately from the associated record data field RMS uses the following types of variable length record formats V LSB format Applies to variable length records in disk files RMS prefixes the data portion of each variable length V LSB record with a 2 byte binary count field in LSB format that specifies the length of the record in bytes excluding the count field itself Choosing a File Organization 2 9 Choosing a File Organization 2 1 Record Concepts V MSB format Applies to variable length records in disk files RMS prefixes the dat
359. mation specified by the processes that access the file Magnetic tape files cannot be shared because magnetic tape drives are sequentially operated devices However disk files can be shared by any combination of readers and writers without restriction Your program provides the information that enables file sharing You control the degree of sharing File Sharing and Buffering 7 1 File Sharing and Buffering 7 1 File Accessing by providing an explicit file sharing specification when your program opens or creates a file This specification indicates the types of file operations that are permitted for application programs that share the file When a program creates or opens a disk file it gives two pieces of information needed to determine if and how the file may be shared First it states the types of operations it intends to perform on the file such as read write or update RMS later checks this information to protect against unauthorized file access Second the program specifies the types of operations other concurrently active programs can perform on the file When the sharing specification of one program is compatible with the sharing specification of another both programs can gain access to the file simultaneously To ensure that multiple programs can access the file simultaneously you may have to do some schedule planning 7 1 1 Types of File Sharing and Record Streams A single process can access the same file using multiple reco
360. more processes are requesting the same information from a file I O can be minimized because the data is already in the global buffer This is especially true for program sequences in which all of the processes are reading data For shared sequential file operations the first accessor of the file uses the multiblock count to establish the global buffer size for all subsequent accessors Note that RMS also provides each process with local I O buffers to attain efficient buffering capacity 3 14 Performance Considerations Performance Considerations 3 3 Tuning a Sequential File 3 3 5 Read Ahead and Write Behind Options Specifying the read ahead and write behind options for sequential files can improve performance The read ahead and write behind options require at least two I O buffers and the multibuffer attribute Note that using more than two I O buffers usually does not improve performance See Section 3 3 3 Most languages incorporate the read ahead and write behind options by default With some languages you must specify the read ahead and write behind options explicitly using a clause in the language If an OpenVMS language does not have a clause for specifying the read ahead and write behind options you must use a VAX MACRO routine to select these options when you open the file At the VAX MACRO level you can select these options by setting the RAB V_ RAH bit in the RAB L_ROP field for read ahead processing and the RAB V_ WBH
361. move files from one directory tree to another directory tree that is not as deep as the first one e If you specify an output directory with a trailing ellipsis for example A B RMS substitutes the entire wild subdirectory from the related file specification This substitution permits you to move entire subdirectory trees e The related name block must have the appropriate file name status bits set in the NAM L_FNB or NAML L_FNB field set according to the resultant string to allow RMS to identify the wild portion of the resultant string 6 3 Directory Syntax Conventions and Directory Concatenation One of the components of a file specification is the directory specification RMS supports two conventions or types of directory specifications one of which is used more often than the other When RMS applies defaults to a directory specification in a file specification the rules differ depending on what type of a directory specification is present Two directory syntax conventions are available to access directories normal and rooted The default directory access is normal syntax That is you can specify the directory desired using the directory syntax described in the OpenVMS DCL Dictionary 6 3 1 Using Normal Directory Syntax There is a master file directory MFD on each volume Within each MFD top level directories are cataloged using the DCL command CREATE DIRECTORY or equivalent record management services Beneat
362. mployee name in an employment record file Figure 2 13 illustrates the general structure of an indexed file in which the primary key and one alternate key are defined The primary key is the name of the employee the alternate key is the employee badge number in an employment record file Choosing a File Organization 2 21 Choosing a File Organization 2 2 File Organization Concepts Figure 2 12 Single Key Indexed File Organization 39 Sv 0 MZ Jexong Jed pjooei euo seuinssy eyoN SpJooeH ejeq a 7 ZLLSE LSANId SWVGV LS NIYIN NVNAM Qu LIOH HLINS eureN ee Kojdui3 xepu AW NOLLINIJ3Q A3 2 22 Choosing a File Organization Choosing a File Organization 2 2 File Organization Concepts Figure 2 13 Multiple Key Indexed File Organization 39 9v20 4Z f vSecc 1s NIV spuooey ea veZ6l 18 NIV S 62 vc n i I3Av M3 L Mav1o p 22222222222222222222222222222222222222222222 d4 24 TM C ecococcocoscocoecoecoe ccce cocos coco cocco cL T2 62 vc 00012 NVAAM HOTAVL NY ION HLIINS S3NOF Mavio NOLLINIJ3Q A3 Choosing a File Organization 2 23 Choosing a File Organization 2 2 File Organization Concepts 2 2 3 4 Specifying Sort Order RMS lets you specify either ascending sort order or
363. mponent parts of the file specification are referred to as strings For example the device component is referred to as the device string the name component is the name string and so forth Furthermore as components are added to a file specification the expanded file specification is referred to as the expanded string Finally the resultant file specification is called the resultant string Table 6 2 shows the sequence in which defaults are applied to a file specification primary file specification string and the resulting file specification resultant string In Table 6 2 the program specifies the primary file specification string FILE omitting all other components of the file specification The default file specification string DAT provides the file type component The related file specification string does not provide any component strings but the default device 6 2 Advanced Use of File Specifications Advanced Use of File Specifications 6 1 How RMS Applies Defaults string logically SYS DISK provides the device string DISK1 and the directory string INV C is provided by the default directory string Finally because the resultant string is used to specify a new file RMS applies the version number 1 to complete the new file specification Table 6 2 Example of Applying Defaults String Name String Applied Expanded String Primary file specification FILE FILE Default file specification DAT FILE DAT Related file s
364. mpression 3 19 REST command 10 11 10 12 10 15 Restrictions tilde 5 10 Restriction with extended file names 5 10 Retrieval pointer 9 7 Retrieving records sequentially from an indexed file 2 5 Return key interactive mode 10 11 Reverse search key options 8 9 8 17 REVISION attribute 4 32 Revision data 9 10 Rewind service 8 5 effect on next record position 8 18 RFAs record file addresses 1 2 8 14 9 17 10 28 access 10 28 created by CONVERT 3 19 use of table for rapid access 8 3 RMS 1 20 1 31 1 32 1 35 allocating buffers 3 14 3 17 attributes 1 33 1 34 bucket splits 3 24 calculating extension size 3 13 connect time options 4 2 control blocks 1 36 4 13 creation time options 4 2 4 15 data structures 1 36 deferred write operation 3 18 3 28 image activation 5 17 in indexed files 3 18 MACRO parameter 3 15 option selection 9 1 overflow into PO 7 18 placing file information in prologs 3 18 statistics cache display 3 31 determining when enabled 3 29 displaying 3 30 enabling gathering 3 29 example of using 3 30 impact on resources associated with global sections 3 29 restrictions to gathering 3 29 using to improve performance 3 30 truncation error 3 9 requesting 3 9 use with large extends 3 9 use of multiblocks 3 14 using with languages 1 35 utilities ANALYZE RMS FILE 1 37 RMS utilities contd CONVERT 1 38 CONVERT RECLAIM 1 38
365. mproves performance when retrieving successive previous records specify full key sizes and select the next key option The following C program demonstrates the use of the search key option The program reads the last and the next to last records in a file REVERSE SEARCH The file is defined by the logical INFILE and has record and key sizes defined below include lt rms gt defines rabs and fabs include lt stdio gt defines printf include lt string gt defines strlen include lt stdlib gt defines exit include lt starlet gt defines sys open et al define RECORD SIZE 80 define KEY SIZE 10 char INPUT NAME INFILE struct FAB infab struct RAB inrab error exit code value long code long value void lib signal lib signal code value exit 0 main char record RECORD SIZE 1 record buffer char key KEY_SIZE 1 key buffer long status 8 10 Record Processing Record Processing 8 4 Record Access for the Various File Organizations Set up input fab infab cc rms fab infab fab b fac FABSM GET FAB M PUT FAB M UPD FAB M DEL infab fab b shr FABSM SHRGET FABSM SHRPUT FAB M SHRUPD FABSM SHRDEL read write sharing z infab fab l fna INPUT NAME logical name INFILE infab fab b fns sizeof INPUT NAME 1 Set up input rab inrab cc rms rab inrab rab 1 fab amp infab inrab rab
366. n 8 8 8 9 Next record position 8 18 use with sequential access 8 17 Next Volume service 8 5 Node component 5 2 local 5 2 remote 5 2 Nodes lock mastering 3 33 lock requesting 3 33 NOLOCK attribute 7 13 NONEXISTENT RECORD attribute 7 16 8 8 Nonstandard file processing run time options 9 14 No query locking 7 10 Normal directory syntax 6 11 to 6 13 Null keys for improving performance 3 22 O ODS 1 comparing with ODS 2 1 4 comparing with ODS 2 and ODS 5 1 4 ODS 1 disks 3 29 ODS 2 comparing with ODS 1 and ODS 5 1 4 ODS 2 on Alpha and VAX systems 5 12 ODS 5 on Alpha systems 5 13 ODS 5 on VAX systems 5 12 On disk components 5 4 character set 5 4 On disk representation 5 5 Open by name block option 5 22 6 5 performance and 6 6 Open service 5 22 for process permanent files 6 22 OpenVMS Cluster environments 3 32 locking considerations 3 33 Optimization Edit FDL utility A 1 of indexed files 10 26 ORGANIZATION attribute 4 32 OWNER attribute 4 33 Index 10 P PO region used for RMS buffers 7 18 Parity bit 1 18 Parse service 5 21 to 5 25 Parsing file specifications 6 4 See also File specification parsing Pascal program example calling FDL PARSE and FDL RELEASE routines 4 13 Pending bad block log file 1 10 Performance 3 1 asynchronous processing and 9 8 buffers 9 9 deferred write option 3 28 9 8 effect of compression 3
367. n is in progress because the results are unpredictable If you issue a second record operation request for the same stream before a previous request is completed you receive an RMS RSA or RMS BUSY error status code indicating that the record stream is still active This can also occur when an AST level routine attempts to use an active record stream the original I O request may be synchronous or asynchronous An additional error RMS BUSY can be encountered by attempting an operation using the same record stream RAB from an error or success routine when the main program is awaiting completion of the initial operation In all cases it is your responsibility to recognize this possibility and prevent the problem Most problems can be prevented by using a Wait service When the Wait service concludes it returns control to your program Note that the Connect operation may be performed asynchronously If the RAB V ASY option is set a Wait service should follow the Connect service to synchronize with the completion of the Connect service Another technique is to use the Connect service synchronously and set the RAB V_ASY option at run time after the Connect service Record Processing 8 19 9 Run Time Options This chapter describes the way you specify run time options and summarizes the run time options available to you when opening files connecting record streams processing records and closing files The run time options that app
368. n marks is part of the name string rather than a delimiter Embedded spaces also are valid characters but embedded tabs are not Lowercase characters are not in the ASCII a character set but if you specify them OpenVMS systems convert them to uppercase characters If you do not specify a file type or version number on input OpenVMS systems supply a period the default file type and a semicolon the default version number However the period and semicolon will not be written to this field on the tape Although the operating system considers version numbers for ANSI magnetic tape file names and OpenVMS file names to be part of the file name specification the version number of a file is not written to the file identifier field but is mapped to the generation number and generation version number fields as described in Generation Number and Generation Version Number Fields Examples below display ANSI magnetic tape file names The input is the format that you specify The output shown displays the OpenVMS format returned to your process and the format written to the label The number sign in the examples indicates a space character In the last example an OpenVMS file name is enclosed in quotation marks like an ANSI magnetic tape file name on input However the operating system returns the file name to the process as an OpenVMS file name rather than as an ANSI magnetic tape file name Therefore when you enclose a valid OpenVMS
369. n next page 10 20 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics Example 10 6 Cont Examining a Primary Record PRIMARY DATA RECORD VBN 4 offset X 000E Record Control Flags 2 IRC V DELETED 0 3 IRC V RRV 0 4 IRCSV NOPTRSZ 0 Record ID 1 RRV ID 1 4 Byte Bucket Pointer 4 Key 7 65 4 3 2 10 01234567 31 30 30 30 30 30 0000 000001 ANALYZE gt DOWN RRV BUCKET HEADER VBN 4 Check Character X 00 Area Number 0 VBN Sample 4 Free Space Offset X 0104 Free Record ID Range 4 255 Next Bucket VBN 4 Level 0 Bucket Header Flags 0 BKT V LASTBKT 1 1 BKT V ROOTBRT 0 Figure 10 7 displays the structure of the alternate records Figure 10 7 Structure of Alternate Records Alternate eee Record SIDR SIDR eee Pointer ZK 0333 GE Maintaining Files 10 21 Maintaining Files 10 1 Viewing File Characteristics Example 10 7 shows an examination of an alternate record Example 10 7 Examining an Alternate Record ANALYZE DOWN SIDR RECORD VBN 6 offset X 000E Control Flags 4 IRC V NOPTRSZ 0 Record ID 1 Key 7 65 4 3 2 1 0 01234567 31 36 30 33 30 0000 03062 ANALYZE gt DOWN sidr pointer control flags 2 IRC V DELETED 0 5 IRC V KEYDELETE 0 sidr pointer record id 1 4 byte record VBN 4 10 2 Generating an FDL File from a Data File You can use the Analyze RMS File utility to create an FDL file generally called an analysis file
370. n the selected record s key when you are locating or reading records randomly e FDL None e RMS RAB L_KBF Key size Specifies that only a portion of the key be used to locate the selected record when you are locating or reading records with a string data type key e FDL None e RMS RAB B_KSZ Limit key Returns an alternate success status if the record key exceeds the specified key when you are locating or reading records sequentially e FDL CONNECT KEY LIMIT e RMS RAB L ROP RAB V LIM Load buckets Uses the fill factor specified when the file was created When you are adding records to an index file By default RMS fills buckets completely e FDL CONNECT FILL BUCKETS e RMS RAB L_ROP RAB V LOA l Indicates an option that can be specified for each record processing operation For more information see Section 9 3 9 2 9 Options for Magnetic Tape Processing The run time file open and close options that apply to magnetic tape processing are listed in the following table Option Description Not end of file Adds a record to a location other than at the end of the file e FDL FILE MT_NOT_EOF e RMS FAB L_FOP FAB V_NEF Run Time Options 9 13 Run Time Options 9 2 Options Related to Opening and Closing Files Option Description Current position Rewind on Open Rewind on Close Positions the tape to the location immediately following the most recently closed file when you select this opt
371. nation e You can refer to the default directory explicitly by specifying an empty directory specification at the DCL prompt This feature is useful when you want to use a single DCL command to perform directory operations in your default directory and one other directory For example assume you have a directory on device USERDISK named CUSTOMERS LOCAL that contains three files ABERCROMBIE FITCH and GOULD Another directory named CUSTOMERS INTERNATIONAL also contains three files MERRILL LYNCH and PIERCE Assume that your default directory is CUSTOMERS LOCAL but you need a directory listing that contains the sizes of all customer files You can list both directories using the following command line DIRECTORY SIZE CUSTOMERS INTERNATIONAL DCL responds to this command with the following display Directory USERDISK CUSTOMERS INTERNATIONAL MERRILL 1100 LYNCH 155 PIERCE 645 Directory USERDISK CUSTOMERS LOCAL ABERCROMBIE 230 FITCH 100 GOULD 355 Total of 6 files 2585 blocks A directory name at the leftmost end of a directory specification is interpreted as a top level directory or an absolute directory reference The syntax shown for the following specification refers to a top level directory named GREEN regardless of the current default directory GREEN Conversely a period or a hyphen before a directory name is always associated with a relative directory reference Note that because only one direct
372. nce Conversely avoid the fast delete option for most read only indexed files and for indexed files that are infrequently updated For more information about the Delete service refer to the OpenVMS Record Management Services Reference Manual 8 3 Secondary Services This section provides very brief descriptions of the secondary services Note that each of the services performs a specialized function with few options Connect Allows you to connect to a single record stream or to multiple record streams Disconnect Allows you to disconnect a record stream This is done implicitly when a file is closed but when using multiple record streams you may want to disconnect one record stream but not others Flush Writes modified I O buffers and file attribute information maintained in memory to the file Free Releases all record locks established by the current record stream Next Volume Continues the next volume of a magnetic tape volume set This service applies only to sequential files Release Releases the record lock on the current record Rewind Positions the record stream context to the first record of the file Truncate Truncates a file beginning with the current record effectively deleting it and all remaining records This service applies only to sequential files Wait Awaits the completion of an asynchronous record operation or Connect service In addition to the record processing services a variety of file processing s
373. nd ANALYZE RMS FILE display a more easily remembered mnemonic for the DDIF tag instead of the hexadecimal value Assigning a name to the tag also aids in using the SEMANTICS qualifier with the DCL SET FILE command when you want to tag a file from the DCL interface For example you can use a command like the following SET FILE SEMANTICS DDIF MY FILE To assign a tag a name you must have privileges to make appropriate entries in two system tables RMS SEMANTIC TAGS and RMS SEMANTIC OBJECTS Creating and Populating Files 4 19 Creating and Populating Files 4 3 Creating and Accessing Tagged Files For example the following DCL commands have been included in the system startup command file to assign the mnemonic DDIF to the hexadecimal value for a DDIF tag DEFINE TABLE RMS SEMANTIC TAGS DDIF 2B0C8773010301 DEFINE TABLE RMS SEMANTIC OBJECTS 2B0C8773010301 DDIF With the appropriate DEFINE commands you can assign mnemonics for other tags including tags used with international program applications You can tag files through the DCL interface the FDL interface or from your program by way of the RMS interface This section describes the implementation of tagged files through the RMS interface including e Tagging files e Accessing tagged files e Preserving tags 4 3 1 Programming Interface for File Tagging You can tag a file from the RMS interface by using the Create service in conjunction with an item XAB XABITM See O
374. nd RMS s Subdirectory Limit 6 18 6 4 DID Abbreviated Directories Alpha Only llle 6 19 6 5 FID Abbreviated Names Alpha Only 0 00 0 eee 6 20 6 5 1 Restrictions on FID Abbreviated Names 0000000 6 21 6 6 Using Process Permanent Files 0 0 00 cece eee eens 6 21 7 File Sharing and Buffering 7 1 Fil Accessin mereri gosh a ies Sor e ruo e SR OC ue e PR RUF NL Oe 7 1 7 1 1 Types of File Sharing and Record Streams uun 7 2 7 1 2 Interlocked Interprocess File Sharing 00005 7 5 7 1 3 User Interlocked Interprocess File Sharing 05 7 6 7 2 Record locking ue ae koe ha ee a Tam go e EP de 7 7 7 2 1 Default Record Locking 0 0 0 00 eens 7 8 7 2 2 Record Locking Options l l 7 8 7 2 2 1 Exclusive Locking 0 0 ccc eee eee 7 9 7 2 2 2 Write Lockingz 6 6 i840 3 ack as ae REA RP RUE es 7 9 7 2 2 3 Read Locking 22 4229 E Chee EG AERE Yd d i 7 10 7 2 2 4 No Locking Query Locking llle eee 7 10 7 2 2 5 No Query Record Locking Option Alpha Only 7 10 7 2 2 6 Put Service Considerations 0 00 eee eee eens 7 12 7 2 2 7 UM MALY 2309 506 Sue ie a Mae hag aO ae ae OT e ew ee ta 7 13 7 2 3 Handling Record Locking Conflicts 0 0 7 13 7 2 3 1 Handling the Record Locked Error 000000 7 14 7 2 3 2 Waiting for Locked Records 00000 e eee eee eens
375. nd addition of a new index s parameters Delete Key removal of the highest index s parameters Indexed modeling of parameters for an entire Indexed file Optimize tuning of all indexes parameters using file statistics Relative selection of parameters for a Relative file Sequential selection of parameters for a Sequential file Touchup remodeling of parameters for a particular index Editing Script Title Keyword INDEXED Target disk volume Cluster Size 1 1Giga 3 3 Number of Keys to Define 1 255 1 1 Line Bucket Size vs Index Depth as a 2 dimensional plot Fill Bucket Size vs Load Fill Percent vs Index Depth key Bucket Size vs Key Length vs Index Depth Record Bucket Size vs Record Size vs Index Depth Init Bucket Size vs Initial Load Record Count vs Index Depth Add Bucket Size vs Additional Record Count vs Index Depth Graph type to display Keyword Line LINE Number of Records that will be Initially Loaded into the File 0 1Giga 100000 10 Fast Convert NoFast Convert RMS Puts Initial File Load Method Keyword Fast FAST Number of Additional Records to be Added After the Initial File Load 0 1Giga 0 0 key 0 Load Fill Percent 50 100 100 100 D Fixed Variable Record Format Keyword Var VARIABLE Mean Record Size 1 32229 80 continued on next page Creating and Populating Files 4 5 Creating and Populating Files 4 1 File Creation Characteristics Example 4 1 Cont Sample Edit
376. nd of file Put relative file Sequential None Next record position Put indexed file Sequential None Undefined continued on next page Record Processing 8 15 Record Processing 8 6 Current Record Context Table 8 3 Cont Record Access Stream Context Service Access Mode Current Next Put Random None Unchanged Find Sequential Old next New current record record 1 Find Random New Unchanged Update Not applicable None Unchanged Delete Not applicable None Unchanged Truncate Not applicable None End of file Rewind Not applicable Unchanged First record Free Not applicable None Unchanged Release Not applicable None Unchanged Notes to Table 8 3 1 Except for the Truncate service RMS establishes the current record position before establishing the next record position 2 The notation 1 indicates the next sequential record as determined by the file organization For indexed files the current key of reference is part of this determination 3 The Connect service on an indexed file establishes the next record to be the first record in the index represented by the RAB key of reference RAB B_ KRF field 4 The Connect service leaves the next record as the end of file for a magnetic tape file opened for Put services unless the FAB V_NEF option in the FAB L_FOP is set 8 6 1 Current Record Position For the Update Delete Release and Truncate services the current record position reflects the location of the tar
377. ndency for index file data buckets to be placed into local buffers even when a large global buffer cache is present By varying the number of local buffers and re examining these statistics you can pick an optimal number of local buffers As always you should check that any buffering changes do not result in additional paging I Os Performance Considerations 3 31 Performance Considerations 3 6 Monitoring RMS Performance There are other MONITOR utility screens that display information on the rate of various RMS operations being done by the application the data transfer size per operation and the locking rates associated with RMS operations The locking rate screen also displays the number of bucket splits occurring for an indexed file To display all monitor RMS statistics screens use the following command MONITOR MONITOR RMS FILE DATABASE DAT ITEM ALL For more information about using the SET FILE STATISTICS command see the OpenVMS DCL Dictionary The OpenVMS System Manager s Manual provides detailed information about using the Monitor utility For more information on performance management see Guide to OpenVMS Performance Management and A Comparison of System Management on OpenVMS AXP and OpenVMS VAX 3 7 Processing in an OpenVMS Cluster Environment This section discusses designing file applications for an OpenVMS Cluster and the performance you can reasonably expect from the OpenVMS Cluster environment Note In this do
378. ndex Area 1 Data Area 0 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 10 Key Flags 0 KEY V DUPKEYS 3 KEYSV IDX COMPR 4 KEYSV INITIDX 6 KEY V KEY COMPR 7 KEY V REC COMPR Key Segments 1 Key Size 4 Minimum Record Size 4 Index Fill Quantity 512 Data Fill Quantity 512 Segment Positions Segment Sizes 4 Data Type string Name ID NUM First Data Bucket VBN 4 Wo rc c0 cc STATISTICS FOR KEY 0 10 8 Maintaining Files Number of Index Levels 1 Count of Level 1 Records 1 Mean Length of Index Entry 6 Count of Index Blocks 1 Mean Index Bucket Fill 4 Mean Index Entry Compression 0 Count of Data Records 10 Mean Length of Data Record 33 Count of Data Blocks 1 Mean Data Bucket Fill 90 Mean Data Key Compression 0 Mean Data Record Compression 2 Overall Space Efficiency 2 continued on next page 29 Maintaining Files 10 1 Viewing File Characteristics Example 10 2 Cont Using ANALYZE RMS FILE to Create a Statistics Report KEY DESCRIPTOR 1 VBN 2 offset X 0000 Next Key Descriptor VBN 2 Offset X 0066 Index Area 3 Level 1 Index Area 3 Data Area 2 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 16 Key Flags 0 KEYSV DUPKEYS 1 1 KEYSV CHGKEYS 0 2 KEY V NULKEYS 0 3 KEYSV IDX COMPR 0 4 KEY V INITIDX 0 6 KEYSV KEY COMPR 0 Key Segments 1 Key Size 5 Minimum Record Size 9 Index Fill Quantity 512
379. ndex levels of the file in an area on a separate disk Then there is little or no competition for the disk head on the disk that contains the index structures One strategy is to allocate a separate area for level 0 of a primary index the data level These buckets are the only ones referenced when you access the records sequentially by their primary key so keeping them in a separate area optimizes that type of operation Do not allocate separate areas for level 1 of an index and the other index levels if the index has just one level In such a case you force RMS to create an additional level in the index structure In most cases you should allocate at least one area for each alternate index structure By default EDIT FDL creates two areas in an indexed file for each index structure one for the data level and one for all of the index levels You can allocate up to 255 areas so with most applications you can set up enough areas to handle all alternate index structures It is possible to set up a separate area for each of the following e Primary index level 0 the data records e Primary index level 1 the lowest index level e Primary index levels 2 the rest of the index levels e Alternate index level 0 the secondary index data records e Alternate index level 1 the lowest index level e Alternate index levels 2 the rest of the index levels Be sure to allocate sufficient space for each area and to specify area contiguity
380. ndom access by key This procedure can be used to return all records that match a specified duplicate key for a key that allows duplicates An alternative to checking the characters is to specify an ending key value and set the key limit option when the record access mode is changed to sequential When accessing an indexed file randomly by key the key value must reside in the area of memory identified by the control block offset RAB L_KBF When using string keys you should specify the key length in the location identified by control block offset RAB B_KSZ 8 4 4 Access by Record File Address RFA Random access by RFA is supported for all disk files Whenever RMS successfully accesses a record an internal representation of the record s location is returned in the 6 byte RAB field RAB W_RFA When a program wants to retrieve the record using random access by RFA RMS uses this internal data to retrieve the record One way to use RFA access is to establish a record position for later sequential accesses Consider a sequential file with variable length records that can only be accessed randomly using RFA access Assume the file consists of a list of transactions sorted previously by account value Because each account may have multiple transactions each account value may have multiple records for it in the file Instead of reading the entire file until it finds the first record for the desired account number it uses a previously saved RFA v
381. ne It creates an indexed output file named NEW MASTER DAT from the specifications in the FDL file named INDEXED FDL You can also supply a default file name and a result name which receives the name of the created file The program also returns all statistics IMPLICIT INTEGER 4 A Z EXTERNAL LIBSGET LUN FDLSCREATE CHARACTER IN FILE 11 INDEXED FDL 1 OUT FILE 14 NEW MASTER DAT 1 DEF FILE 11 DEFAULT FDL 1 RES FILE 50 INTEGER 2 FIDBLK 3 0 0 0 I 1 STATUS FDL CREATE IN FILE OUT FILE DEF FILE RES FILE FIDBLK IF NOT STATUS CALL LIB STOP VAL STATUS STATUS LIB GET LUN LOG UNIT OPEN UNIT LOG UNIT FILE RES FILE STATUS OLD CLOSE UNIT LOG UNIT STATUS KEEP WRITE 6 1000 RES FILE WRITE 6 2000 FIDBLK I I 1 3 1000 FORMAT 1X The result filename is A50 2000 FORMAT 1X FID NUM I5 1 1X FID SEQ I5 I lX FID RVN I5 END Example 4 5 shows how to call the FDL CREATE routine from a COBOL program Creating and Populating Files 4 17 Creating and Populating Files 4 2 Creating a File Example 4 5 Using the FDL CREATE Routine from a COBOL Program FDLCR COB This program calls the FDLSCREATE routine It creates an indexed output file named NEW MASTER DAT from the specifications in the FDL file named INDEXED DAT You can also supply a default file name and a result name that receives the name of the created file The program also returns the F
382. neous record locking options the manual unlocking option and the lock nonexistent record option in a relative file 7 2 4 4 Manual Unlocking Option The manual unlocking option gives the application program explicit control over releasing a record lock established by the Get service the Find service or the Put service as described in Section 7 2 1 Even if you select the manual unlocking option RMS unlocks affected records when a record stream is disconnected Disconnect service or when a file is closed Close service Other record operations including operations that result in errors do not unlock the record To manually release record locks the application program can invoke the Free service to unlock all record locks held by a record stream or it can invoke the Release service to selectively release record locks using the record s RFA File Sharing and Buffering 7 15 File Sharing and Buffering 7 2 Record Locking Manual unlocking is useful when you have to modify multiple records as part of a single transaction For example assume the application program must modify two related but separate records Assume too that the modified first record must not be accessed by another record stream until modifications to the second record are completed While the program modifies the first record it uses the manual unlocking option to hold the lock on the modified first record It then proceeds to modify the second record while still
383. ng nodes 3 33 Lock root 3 33 LOCK ON READ attribute 7 13 LOCK ON WRITE attribute 7 13 Logical block position option 4 36 Logical names concealed attribute 5 20 concealed device 6 14 parsing 5 11 5 21 rooted device 6 14 sample program 5 17 5 18 search lists 5 20 6 7 6 8 translation 5 20 6 5 6 6 types of 5 20 LOGICAL option 4 36 Lowercase letters 5 7 M MACRO language 3 15 3 18 3 28 4 2 RMS and 9 5 Magnetic tape ancillary control process See MTACP Magnetic tape dating year 2000 readiness 1 30 Magnetic tapes basic concepts of 1 18 processing run time options 9 13 to 9 14 9 track drive 1 20 MANUAL UNLOCKING attribute 7 16 Master File Directories See MFDs MAXIMIZE VERSION attribute 4 31 Maximum record number option 4 33 Maximum record size indexed file 3 23 Maximum record size option 4 33 MAX RECORD NUMBER attribute 4 33 Memory cache 3 14 3 16 3 17 nonpaged system dynamic 9 8 releasing with the FDL RELEASE routine 4 13 MFDs master file directories 1 10 6 11 Modes interactive 10 11 locate performance 9 9 MODIFY command 10 25 Edit FDL utility A 1 Modifying records in occupied cells 2 4 MONITOR command for displaying all RMS statistics screens 3 32 Monitoring RMS performance using RMS statistics 3 29 Monitor utility MONITOR analyzing RMS cache statistics display 3 31 for sampling RMS statistics 3 30 MOUNT com
384. nism is UIC based protection Access control lists permit you to customize security for a file or a directory UIC based protection is determined by an owner UIC and a protection code whereas ACL based protection is determined by a list of entries that grant or deny access to specified files and directories Note You cannot use ACLs with magnetic tape files When you try to access a file that has an ACL the system uses the ACL to determine whether or not you have access to the file If ACL does not explicitly allow or refuse you access or if the file has no ACL the system uses the UIC based protection to determine access See the OpenVMS Guide to System Security for additional information about system security For detailed information about protecting your files directories or volumes see Section 4 4 1 6 RMS Record Management Services OpenVMS Record Management Services OpenVMS RMS or simply RMS is the file and record access subsystem of the OpenVMS operating systems RMS allows efficient and flexible data storage retrieval and modification for disks magnetic tapes and other devices You can use RMS from low level and high level languages If you use a high level language it may not be easy or feasible to use the RMS services directly because you must allocate control blocks and access fields within them Instead you can rely on certain processing options of your language s input output I O statements or
385. nitial accessor can specify multiple SHARING values a subsequent accessor whose ACCESS values match one some or all of the initial accessor s SHARING values is allowed access however when the subsequent accessor specifies an ACCESS value that the initial accessor did not specify as a SHARING value an exception is SHARING GET which is implied access is denied to the subsequent accessor In addition to comparing the file access values that subsequent accessors specify with the file sharing values specified by the initial accessor the values that subsequent accessors specify must be compatible with values specified by the initial accessor Table 7 4 shows the file sharing values that subsequent accessors must specify to access the file Table 7 4 Initial File Access and Subsequent File Sharing Initial Accessor Access Subsequent Accessor Sharing ACCESS GET SHARING GET ACCESS DELETE SHARING DELETE ACCESS PUT SHARING PUT ACCESS UPDATE SHARING UPDATE 1May be implied a related operation Because the initial accessor can specify multiple ACCESS values a subsequent accessor whose SHARING values match all of the initial accessor s ACCESS values is allowed access however when the subsequent accessor specifies a SHARING value that the initial accessor did not specify as an ACCESS value an exception is ACCESS GET which is implied access is denied 7 1 3 User Interlocked Interprocess File Sharing User interlocked inte
386. nitiated Whether the program regains control before the record operation finishes depends on several factors For example the required record may already reside in the I O buffer or the operating system may schedule another process thus possibly allowing a necessary I O operation to be completed before the original program is rescheduled One factor to consider in the use of asynchronous record operations is that you must include a separate completion routine or a wait request in the issuing program This routine or wait request is required to determine when the record operation is completed because the results of the operation are not available and the next record operation for that stream cannot be initiated until the previous operation is concluded 8 7 1 Using Synchronous Operations To declare a synchronous operation you must clear the RAB V_ASY option in the RAB L_ROP field Normally you do not have to clear this option because it is already cleared by default However if the RAB V_ASY option had been set previously then you must explicitly clear it Normally you do not use success and error routines with synchronous operations Instead you test the completion status code for an error and change the flow of the program accordingly However if you use these routines they are executed as asynchronous system traps ASTs before the service returns to your program unless ASTs are disabled 8 18 Record Processing Record
387. nnected Disconnect service e The file is closed Close service e The record stream is positioned to the beginning of the file Rewind service e A new record is added to the file Put service e The record lock is explicitly removed Release service or Free service e An error occurs during a record operation Note that a sequential Get service immediately following a Find service does not unlock the record because it accesses the same record 7 2 2 Record Locking Options Record locking options can be divided into three groups e Options that specify the access allowed by other record streams e Options that control record conflicts between record streams e Miscellaneous options 7 8 File Sharing and Buffering File Sharing and Buffering 7 2 Record Locking All record locking options are specified by RAB input to the accessing service All record locking options apply to the Get service and the Find service and most record locking options apply to the Put service You can specify a different set of record locking options each time the record stream accesses a record This section describe the types of record access allowed by each record locking option It also provides some examples of when an application program might select a particular record locking option The following five record locking options control record access by other record streams e Exclusive locking e Write locking e Read locking e No locking e No que
388. nt the version number of a file even when the version of the specified file already exists on the volume Therefore if the file that you specify has the same file name and version number as an existing file you will have at least two files with the same version number on the same volume set On input OpenVMS systems compute the version number by using this calculation version number generation number 1 100 generation version number 1 Version numbers larger than 32 767 are divided by 32 768 the integer remainder becomes the version number On output the generation number is derived from the version number with this calculation generation number version number 1 100 1 If there is a remainder after the version number is divided by 100 the remainder becomes the generation version number It is not added to 1 to form the generation number Creation Date and Expiration Date Fields The creation date field contains the date the file is created The expiration date field contains the date the file expires The system interprets the expiration date of the first file on a volume as the date that both the file and the volume expire The creation and expiration dates are stored in the Julian format This 6 character format YYDDD permits the symbol to consist of either an ASCII space or an ASCII zero with the YYDDD consisting of a year and day value If an ASCII space is indicated it is assumed that 1900 is adde
389. ntions for advanced file specifications include search lists related file specifications and the way RMS handles directory specifications 6 6 Advanced Use of File Specifications Advanced Use of File Specifications 6 2 Understanding RMS Parsing 6 2 3 1 Parsing Conventions for a Search List RMS uses several conventions when processing a search list logical name When RMS encounters a search list it searches internally for the file using search list file specifications previously specified RMS treats each file specification in the search list as a new file specification That is RMS does not use components of one file specification element in the search list as the default for subsequent elements in the search list When it uses search lists RMS ignores the following errors Invalid device name RMS DEV Device not ready or not mounted RMS DNR Directory not found RMS DNF File not found RMS FNF Privilege violation RMS PRV All other errors terminate search list processing When a search list is embedded nested in another search list all file specifications of the nested search list are processed before the file specifications in the next higher search list level Therefore RMS permits iterative substitution in nested search lists as it does with other logical names For example consider the following search lists X and Y DEFINE X DISKl RED DISK2 WHITE DEFINE Y X DISKl BLUE The following search
390. o Count of Data Records Mean Duplicates per Data Record Mean Length of Data Record Count of Data Blocks Mean Data Bucket Fill Mean Data Key Compression 21 SON 0 4 amp 1 tbN OmbrDp oo Co N O m oo KEY DESCRIPTOR 3 VBN 2 offset X 00CC Index Area 7 Level 1 Index Area 7 Data Area 6 Root Level 1 Index Bucket Size 1 Data Bucket Size 1 Root VBN 28 Key Flags 0 KEY V DUPKEYS 1 KEY V CHGKEYS 2 KEYSV NULKEYS 3 KEY V IDX COMPR 4 KEYSV INITIDX 6 KEY V KEY COMPR Key Segments 1 Key Size 10 Minimum Record Size 29 Index Fill Quantity 512 Data Fill Quantity 512 Segment Positions 19 Segment Sizes 10 Data Type string Name CHARGES First Data Bucket VBN 25 STATISTICS FOR KEY 3 omob ooo Number of Index Levels Count of Level 1 Records Mean Length of Index Entry Count of Index Blocks Mean Index Bucket Fill Mean Index Entry Compression me C oo Count of Data Records Mean Duplicates per Data Record Mean Length of Data Record Count of Data Blocks Mean Data Bucket Fill Mean Data Key Compression 34 Co r2 U ORE PO ILS 5 oe N N oi e oo The analysis uncovered NO errors ANALYZE RMS FILE OUTPUT INDEX STATISTICS INDEX DAT 10 10 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics 10 1 3 Using Interactive Mode The INTERACTIVE qualifier begins an interactive session in which you can examine the structu
391. o the index root bucket to determine which bucket at the next lower level is the next link in the bucket chain seek time The time required to position the read write heads over the selected track sequential file organization The arrangement of records in a file in one after the other fashion Records appear in the order in which they were written sequential record access mode Record storage or retrieval that starts at a designated point in the file and continues in one after the other fashion through the file That is records are accessed in the order in which they physically appear in the file shared access A file management technique that allows more than one user to simultaneously access a file or a group of files stream An access window to a file associated with a record access control block RAB supporting record operation requests stream record format Property of a file specifying that the data in the file is interpreted as a continuous sequence of bytes without control information except for terminators that are recognized as record separators Stream record format applies to sequential files only synchronous record operation An operation in which your program does not regain control until after the completion of a record retrieval or storage request See also asynchronous record operation terminator Special characters or character sequences used to delimit the records in files using the stream record
392. olume including default file values The following information is included within the home block The volume name Information to locate the remainder of the index file The maximum number of files that can be present on the volume at any given time The user identification code UIC of the volume owner Volume protection information specifies which users can read and or write the entire volume The home block identifies the disk as a Files 11 ODS volume Initially the home block is the second block on the volume Files 11 ODS volumes contain several copies of the home block to ensure that accidental destruction of this information does not affect the ability to locate other files on the volume If the current home block becomes corrupted the system selects an alternate home block e Alternate home block The alternate home block is a copy of the home block It permits the volume to be used even if the primary home block is destroyed e Alternate index file header The alternate index file header permits recovery of data on the volume if the primary index file header becomes damaged e Index file bit map The index file bit map controls the allocation of file headers and thus the number of files on the volume The bit map contains a bit for each file header allowed on the volume If the value of a bit for a given file header is 0 a file can be created with this file header If the value is 1 the file hea
393. on 2 17 Choosing a File Organization 2 2 File Organization Concepts Note that because the records are variable length records each is prefixed by 3 bytes the 2 byte count field described in Section 2 1 2 2 and a 1 byte field that indicates whether or not the cell is empty a delete flag These bytes are used only by RMS you need not be concerned with them except when planning the files space requirements Figure 2 11 Variable Length Records in Fixed Length Cells Fixed Length Cells 256 Bytes 256 Bytes 256 Bytes ee A Record 1 Record 2 Record 3 192 Bytes Used 128 Bytes Used All 253 Bytes Used Legend E RMS Control Information Bytes E Unused Bytes ZK 0744 GE Some advantages and disadvantages of relative file organization are outlined in Table 2 4 Table 2 4 Relative File Organization Advantages and Disadvantages Advantages Disadvantages Random access in all languages Restricted to disk devices Allows deletions File contains a cell for each cell number between first and last record in file limits data density Allows random Get and Put operations Program must know relative record number or RFA before it can randomly access the data no generic access as in indexed file organization Random and sequential access with low Interactive access can be awkward if you do overhead not access records by relative record number Can be write shared You can only insert records into unused record cells
394. on disk has a unique file address the record file address RFA that provides another way to randomly retrieve records in all types of file organizations Note RFA mode provides the only means of randomly accessing variable length records in a sequential file An important feature of the RFA is that it remains constant as long as the record is in the file RMS returns the RFA to your program each time the record is retrieved or stored Your program can either ignore the RFA or keep it as a random access pointer to the record for subsequent accesses Figure 2 5 contains two illustrations The first shows that when a record is stored its RFA is returned to the program The second shows that when the program wants to access the record randomly it provides RMS with the RFA Choosing a File Organization 2 7 Choosing a File Organization 2 1 Record Concepts Figure 2 5 Random Access by Record File Address User Program Write Record B Record File Address User Program Read Record by RFA Record File Address ZK 0751 GE 2 1 2 Record Formats Except for the key values that are part of the records in indexed files RMS is less concerned with the record content than with the record s format that is the way the record physically appears on the recording surface of the storage medium RMS supports four record formats e Fixed length format e Variable length format e Variable length with fixed lengt
395. on next page 10 2 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics Example 10 1 Cont Using ANALYZE RMS FILE to Create a Check Report FIXED PROLOG Number of Areas 8 VBN of First Descriptor 3 Prolog Version 3 AREA DESCRIPTOR 0 VBN 3 offset X 0000 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 1 Blocks 9 Used 4 Next 5 Default Extend Quantity 2 Total Allocation 9 AREA DESCRIPTOR 1 VBN 3 offset X 0040 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 10 Blocks 3 Used 1 Next 11 Default Extend Quantity 1 AREA DESCRIPTOR 2 VBN 3 offset X 0080 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 13 Blocks 3 Used 1 Next 14 Default Extend Quantity 1 Total Allocation 3 AREA DESCRIPTOR 3 VBN 3 offset X 00C0 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 16 Blocks 3 Used 1 Next 17 Default Extend Quantity 1 Total Allocation 3 AREA DESCRIPTOR 4 VBN 3 offset X 0100 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 19 Blocks 3 Used 1 Next 20 Default Extend Quantity 1 Total Allocation 3 AREA DESCRIPTOR 5 VBN 3 offset X 0140 Bucket Size 1 Reclaimed Bucket VBN 0 Current Extent Start 22 Blocks 3 Used 1 Next 23 Default Extend Quantity 1 Total Allocation 3 AREA DESCRIPTOR 6 VBN 3 offset X 0180 Bucket Size 1 Reclaimed Bucket
396. one appendix and a glossary Chapter 1 provides general information on file disk and magnetic tape concepts and brief overviews of available media RMS FDL and resource requirements Chapter 2 describes the file organizations and record access modes to help you choose the correct file organization for your application Chapter 3 discusses general performance considerations and specific decisions you can make in the design of your application Chapter 4 describes procedures necessary to create files populate files with records and protect files Chapter 5 describes file specifications and the procedures needed to use them Chapter 6 describes the rules of file specification parsing and advanced file specification use Information about rooted directories is also provided Chapter 7 describes file sharing and buffering including record locking and the use of global buffers Chapter 8 describes aspects of record processing including record access modes synchronous and asynchronous record operations and retrieving inserting updating and deleting records Chapter 9 describes how to specify run time options and summarizes the run time options available when a file is opened and closed and when records are retrieved inserted updated and deleted Chapter 10 describes procedures needed to maintain properly tuned files with the emphasis on efficiently maintaining indexed files Appendix A describes the algorithms used by th
397. onvert utility CONVERT and the Edit FDL utility EDIT FDL FDL files created with ANALYZE RMS FILE contain special analysis sections for each area and key which are called ANALYSIS OF AREA and ANALYSIS OF KEY The Edit FDL utility uses these sections in the Optimize script to tune the file s structure 10 1 1 Performing an Error Check To check a file s structure for errors use the following command syntax ANALYZE RMS FILE CHECK filespec By default with a command of this format the Check report is displayed on the terminal SYS OUTPUT Maintaining Files 10 1 Maintaining Files 10 1 Viewing File Characteristics If you receive any error messages the file has been corrupted by a serious error If you have had a hardware problem such as a power failure or a disk head failure then the hardware probably caused the corruption If you have not had any hardware problems then a software error may have caused the corruption Note that the CHECK qualifier does not find all types of file corruption however In either case you can try using the Convert utility to fix the problem by using the file specification as both the input filespec and the output filespec Note that if you are processing a relative file containing deleted or unused records the conversion process changes relative record numbers RRN in the output file If the conversion does not correct the problem use the Backup utility BACKUP to bring in the backup copy of the f
398. or information about language statements and their keywords Consult the OpenVMS Record Management Utilities Reference Manual for information about the FDL Editor and refer to the OpenVMS Utility Routines Manual for information about the FDL PARSE and FDL RELEASE routines For detailed information about RMS control blocks and services see the OpenVMS Record Management Services Reference Manual 6 2 Understanding RMS Parsing In the following text the term expanded string buffer refers to the user allocated buffer that is pointed to by the NAM block expanded string address field NAM L ESA by the NAML block short expanded string address field NAML L_ESA or by the NAML block long expanded string address field NAML L LONG EXPAND As it processes each program supplied file specification RMS identifies each specification s component parts Components present in the primary default or related and process default file specifications are used to form the expanded file specification The expanded file specification can then be used to locate one or more files If a name block NAM or NAML is present and the address and size of the expanded string buffer are specified the file specification is copied into the expanded string buffer Note that the Parse service operates differently from other services with regard to the expanded string With the Parse service the expanded string contains all wildcard characters present in the file specifica
399. ord User Action Count Fixed Control Area Process Data Separate Record Data Portion User Action Fixed Control Area Portion ZK 0756 GE 2 1 2 4 Stream Record Format There are four variations of stream record format Special characters or character sequences called terminators delimit the records in files using the first three variations STREAM CR This variation uses a carriage return as the terminator STREAM LF This variation uses a line feed as the terminator STREAM This variation ignores leading zeros and uses a terminator from a limited set of special characters the line feed LF the carriage return line feed combination CR LF the form feed FF or the vertical tab VT UNDEFINED This variation has no terminator The length of each record is determined by the size of the user buffer maximum 65 535 bytes or the end of file RMS supports the stream record format for sequential files on disk devices only In a stream formatted file RMS treats the data as a continuous stream of bytes without control information Stream records are always permitted to span block boundaries 2 2 File Organization Concepts The terms file organization and access mode are closely related but they are distinct from each other nonetheless You establish the physical arrangement of records in the file the file organization when you create it The organization of a file cannot be changed unless you use a utility
400. ord Processing 8 4 Record Access for the Various File Organizations Note The string data type keys include STRING DSTRING COLLATED and DCOLLATED keys RMS uses this information to return the first record with a key value that begins with these characters and meets the specified sorting order requirement This is useful when attempting to locate a record when only part of the key is known or for applications in which a series of records must be retrieved when only the initial portions of their key values are identical Generic key match is available for string keys only For example if the program specifies the next key option with a generic match on the three characters RAM using ascending sort order RMS returns records with key values RAMA RAMBO and RAMP in that order A record having the same key value RAM is not returned If you specify the next key option and descending sort order RMS returns records with key values RAMP RAMBO and RAMA in that order When a generic key match is used with various approximate key match options the results can vary as shown in the following example Consider using a key value of ABB to access records having key values of ABA ABB and ABC respectively e Ifthe program elects to use the equal or next key option with ascending sort order and a 3 character generic match RMS returns the record containing the key ABB e Ifthe program uses the next key option with ascending sort order
401. ord position in an indexed file and then retrieve records sequentially by a specified sort order Note however that changing modes in this manner requires program access to the RAB B_RAC control block field at run time The record access mode in conjunction with the file organization is what determines the manner in which a record is selected In the following sections the sequential and random access modes are discussed in the context of the applicable file organizations Random access by RFA is discussed separately because it applies to disk files regardless of file organization 8 6 Record Processing Record Processing 8 4 Record Access for the Various File Organizations The following discussion of record access modes is directed primarily toward services that insert records and services that retrieve records For additional details about these services see the OpenVMS Record Management Services Reference Manual 8 4 1 Processing Sequential Files A program can read sequential files on both tape and disk devices using the sequential record access mode If the file resides on disk the random access by RFA mode can be used to read records and if the file uses the fixed length record format the random access by relative record number mode is permitted You can add records only to the end of a sequential file All record access modes permit you to establish a new current record position in a sequential file using the Find servi
402. ords to an indexed file consider choosing the deferred write option FDL attribute FILE DEFERRED WRITE FAB L_FOP field FAB V DFW With the deferred write option the buffer into which the records have been moved is not written to disk until the buffer is needed for other purposes or until the file is closed This option however may cause records to be lost if a system crash should occur before the records are written to disk To see the current process default buffer count use the DCL command SHOW RMS DEFAULT To set the process default buffer count use the DCL command SET RMS_DEFAULT INDEXED BUFFER_COUNT n where n is the number of buffers 7 3 6 Using Global Buffers for Shared Files Two types of buffer caches are available using RMS local and global Local buffers reside within process program memory space and are not shared among processes even if several processes access the same file and read the same records Global buffers which are designed for application programs that access the same files and perhaps the same records do not reside in process memory space If several processes share a file you should specify that the file uses global buffers A global buffer is an I O buffer that two or more processes can access in conjunction with file sharing If two or more processes request the same information from a file each process can use the global buffers instead of allocating its own process local buffers Figure 7 3 illustra
403. ory CD ROM discs and CD ROM readers used with computers are very similar to the CD ROMs and CD ROM readers used for audio applications and may incorporate the same hardware The major difference is that CD ROM disc readers used with computers have a digital interface that incorporates circuitry which provides error detection and correction logic to improve the accuracy of the disc data CD ROMs provide the following advantages when used to store data e Direct access of data allowed e Typically less expensive than other direct access media e Large storage capability Currently you can store approximately 650 megabytes 1 27 million blocks of data on a CD ROM e Easier to store and handle off line 1 2 5 1 CD ROM On Disc Formats CD ROM media may be formatted according to one or more media formats to incorporate a volume and file structure that is compatible with OpenVMS file system processing OpenVMS supports CD ROM access based on the following media formats e Files 11 ODS 2 OpenVMS On Disk Structure Level 2 e ISO 9660 A volume and file structure standard for information interchange on CD ROMs e High Sierra Working paper of the CD ROM Advisory Committee 1 2 5 2 Volume Structure CD ROM media is divided into logical sectors that are assigned a unique logical sector number Logical sectors are the smallest addressable units of a CD ROM Each logical sector consists of one or more consecutively ascending physical sec
404. ory can be directly above any other directory you can use a hyphen without explicitly naming the next higher directory But because many directories can be directly beneath the current directory you must explicitly specify the directory at the next lower level by following the period with the name of the selected directory If the program omits either the device or the directory component in a file specification RMS accepts the value of the current device and directory from the logical translation of SYS DISK Therefore any directory fields yielded by translation of SYS DISK override the process default directory If translation of SYS DISK does not yield the directory element RMS uses the process default directory Note that you can change the process default directory with the SET DEFAULT command or by invoking the SYS SETDDIR system service Advanced Use of File Specifications 6 13 Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concatenation 6 3 2 Rooted Directory Syntax Applications Rooted directory syntax allows you to refer to directory trees as logical devices and top level directories A reference to a top level directory actually accesses existing subdirectories without program modification thus rooted directory syntax extends the flexibility associated with logical names Similarly rooted directory syntax can reduce the number of top level directories needed for a volume Rooted directory s
405. ot type the brackets on the command line However you must include the brackets in the syntax for OpenVMS directory specifications and for a substring specification in an assignment statement In command format descriptions vertical bars separate choices within brackets or braces Within brackets the choices are optional within braces at least one choice is required Do not type the vertical bars on the command line In command format descriptions braces indicate required choices you must choose at least one of the items listed Do not type the braces on the command line This typeface represents the introduction of a new term It also represents the name of an argument an attribute or a reason Italic text indicates important information complete titles of manuals or variables Variables include information that varies in system output Internal error number in command lines PRODUCER name and in command parameters in text where dd represents the predefined code for the device type Uppercase text indicates a command the name of a routine the name of a file or the abbreviation for a system privilege Monospace type indicates code examples and interactive screen displays In the C programming language monospace type in text identifies the following elements keywords the names of independently compiled external functions and files syntax summaries and references to variables or identifiers introduced in an ex
406. ou can choose one of these scripts at the start of a session or you can instruct the Edit FDL utility to automatically invoke a particular script each time that you enter the EDIT FDL command Table 4 2 lists the seven scripts Table 4 2 Edit FDL Utility Scripts Script Function ADD KEY Allows you to model or add to the attributes of a new index DELETE KEY Allows you to remove attributes from the highest level index of your file INDEXED Begins a dialog in which you are prompted for information about the indexed data file you want to create from the FDL file The Edit FDL utility supplies values for certain attributes OPTIMIZE Helps you redesign an FDL file using an analysis file from the Analyze RMS File utility ANALYZE RMS FILE FDL The FDL file itself is one of the inputs to the Edit FDL utility In effect this script allows you to tune the parameters of your indexes using the file statistics from the FDL ANALYSIS sections produced by ANALYZE RMS FILE RELATIVE Begins a dialog in which you are prompted for information about the relative data file to be created from the FDL file The Edit FDL utility supplies values for certain attributes SEQUENTIAL Begins a dialog in which you are prompted for information about the sequential data file to be created from the FDL file The Edit FDL utility supplies values for certain attributes TOUCHUP Begins a dialog in which you are prompted for information about how you want to c
407. pecification None FILE DAT Default device SYS DISK DISK1 DISK1 FILE DAT Default directory INV C DISK1 INV_C FILE DAT Resultant string DISK1 INV_C FILE DAT 1 RMS appends the version number to the expanded string to convert it into the resultant string The resultant string is the resultant file specification that RMS uses to locate the file When coding the file specification information in a program you can use the language keyword for the OPEN or CREATE statement Then you use the FDL Editor to enter the file specification characteristics Finally you call the FDL CREATE routine to create a file or you call the FDL PARSE routine and the FDL RELEASE routine to open a file Alternatively you can set the appropriate control block fields and call the RMS services directly perhaps as part of a USEROPEN routine or a USER ACTION routine Consider a program that does not explicitly specify the device and directory in any of the file specifications and does not have a related file specification RMS adds the current process default device and the current process default directory to the expanded string after it applies components provided by the default file specification However if the program looks for a data file that is not in the current process default device and directory it does not find the file In this case the solution is to specify the data file s device and directory either in the primary file specification the
408. pecifying a file specification that contains a search list For example consider the case of a directory that contains the file PAY DAT and a backup copy of the file named PAY BUP DAT You could specify a file name of PAY DAT in the file specification and invoke the Parse service once and the Search service once to locate either of the two files this method will locate PAY DAT before PAY BUP DAT A potential problem arises if the file PAY DAT has been deleted or renamed In this case unless the program determines that the file specification is one of several that are acceptable any file named PAY that has the file type DAT could be accessed for example PAY ACC DAT You can avoid such problems by defining a search list logical name that specifies a search for PAY DAT and PAY BUPDAT A search list named SEARCH could be defined as follows for the directory SMITH DEFINE SEARCH SMITH PAY DAT SMITH PAY BUP DAT To locate the file specify SEARCH as the primary file specification Locating and Naming Files on Disks 5 27 Locating and Naming Files on Disks 5 9 Using One File Specification to Locate Many Files When the file locations to be searched reside in different directories of a directory tree you can use the ellipsis wildcard character in the directory field to search all subdirectories Alternatively you could define a search list that searches for the file PAY DAT in one directory the same file name in a subdirectory and
409. penVMS Record Management Services Reference Manual for more information about using the XABITM macro Example 4 6 illustrates a BLISS 32 program that tags a DDIF file through the RMS interface The tag value shown is a 7 byte hexadecimal number representing the code for the DDIF tag The RMS program interface accepts only hexadecimal tag values To write to a tagged file the application program must use a XABITM macro to specify access semantics that match the file s stored semantics as established by a XABITM macro As shown in the example the Create service tags the file and the Connect service specifies the appropriate access semantics 4 20 Creating and Populating Files Creating and Populating Files 4 3 Creating and Accessing Tagged Files Example 4 6 Tagging a File MODULE TYPESMAIN IDENT X 1 MAIN MAIN ADDRESSING MODE EXTERNAL GENERAL BEGIN I FORWARD ROUTINE MAIN NOVALUE Main routine I INCLUDE FILES LIBRARY SYSS LIBRARY LIB OWN NAM SNAM RETLEN DDIF TAG BLOCK 7 BYTE INITIAL BYTE X 2B X 0C X 87 X 73 X O0l X 03 X 01 FAB XABITM T xabitm itemlist ITMLST_UPLIT ITMCOD XAB STORED SEMANTICS BUFADR DDIF TAG BUFSIZ ALLOCATION DDIF_TAG mode SETMODE RAB XABITM E xabitm itemlist ITMLST UPLIT ITMCOD XAB ACCESS SEMANTICS BUFADR DDIF TAG BUFSIZ ALLOCATION DDIF TAG yr mode SETMODE FAB SFAB fnm TAGGED FI
410. phen underscore and dollar sign are valid for OpenVMS file names and types The period and semicolon are the only other valid special characters and they are always separators ANSI magnetic tape file names do not have a file type field An ANSI magnetic tape file name consists of a 17 character name string a period a semicolon and an optional version number You can specify a name string consisting of a maximum of 17 ASCII a characters but you must enclose the string in quotation marks as in for example file name When you specify fewer than 17 characters the string is padded on the right with spaces to the 17 character maximum size If you specify a file name that has trailing spaces OpenVMS systems truncate them when the file name is returned In addition the space padded field prevents you from specifying a unique file name that consists of spaces Although you can specify longer file names up to 79 characters only the first 17 characters of the file name will be used in interchange 1 28 Introduction Introduction 1 3 Magnetic Tape Concepts The quotation mark character requires special treatment because it is both the file name delimiter and a valid ASCII a character that can itself be embedded in the name string You must specify two quotation marks for each one that you want the operating system to interpret The additional quotation mark informs the operating system that one of the quotatio
411. process of looking through the disk directories to find the file If you create a new version of an image but do not install it as a known image and do not remove the old version of the image from the known file list the new image will not run Similarly when you use a search list to specify the image the known file lookup takes precedence Until a lookup is successful or until the search list is exhausted RMS executes a known file lookup for each element on the search list that does not include a file version delimiter If it exhausts the search list RMS uses the search list again this time trying to locate and open the image file on disk If an older version of the image is included in the search list and if RMS finds the older version first it will execute the older version and never look for the new version Be sure to consider this when using search lists 5 6 Sample Use of Logical Names Regardless of the programming language you can use a logical name to provide components of a file specification The following program example shows how to access a remote file You access a remote file in the same way that you access a local file except that the remote file specification includes a node name Locating and Naming Files on Disks 5 17 Locating and Naming Files on Disks 5 6 Sample Use of Logical Names Example 5 1 is a simple Fortran program that transfers a remote file on node TRNTO to the line printer on node BOSTON using th
412. ption is selected If your application program does its own wait and retry handling the deadlock will occur but the lock manager will not detect it The amount of time that lapses before RMS takes action on the deadlock depends on the value specified in the DEADLOCK WAIT system parameter The default value for this system parameter is 10 seconds For further details about how this parameter is set see the OpenVMS System Manager s Manual 7 2 5 1 Record Locking Options to Control Deadlock Detection RMS uses the distributed lock manager ENQ system service for record locking To help prevent false deadlocks the distributed lock manager uses the following flags for lock requests Flag Purpose LCK M NODLCKWT When set the lock management services do not consider this lock when trying to detect deadlock conditions LCK M_NODLCKBLK When set the lock management services do not consider this lock as blocking other locks when trying to detect deadlock conditions lImproper use of these flags can result in the lock management services ignoring genuine deadlocks For complete flag information see the ENQ section of the OpenVMS System Services Reference Manual A GETUAI In previous releases to OpenVMS Version 7 2 1H1 RMS did not set these flags in its record lock requests With OpenVMS Version 7 2 1H1 you can optionally request that RMS set these flags in record lock requests by setting the corresponding options RAB V_
413. ption of the secondary services refer to Section 8 3 and for more detailed descriptions of the secondary services refer to the OpenVMS Record Management Services Reference Manual 8 2 Primary Services This section describes the five services that are functionally similar to related high level language operations The following table provides a brief description of each of these services and cites the similarities to high level languages Find The Find service locates an existing record in the file It does not return the record to your program instead it establishes the record s location as the current record position in the record stream The Find service when applied to a disk or magnetic tape file corresponds to the FIND statement in BASIC and Fortran the START statement in COBOL the FIND and LOCATE statements in Pascal and the READ statement with the SET keyword for PL I Get The Get service returns the selected record to your program The Get service when applied to a disk or magnetic tape file corresponds to is used by the GET statement in BASIC the READ statement in COBOL Fortran and PL I and the GET statement and others in Pascal Put The Put service inserts a new record in the file The Put service when applied to a disk or magnetic tape file corresponds to the PUT and PRINT statements in BASIC the WRITE statement and others in COBOL the WRITE statement in Fortran and PL I and the PUT and WRITELN statements
414. query locking option which requests that RMS take out a lock to probe for status and not hold the lock for synchronization If the lock is not granted exclusive lock held and the read regardless RAB V_RRL option is not set the record access fails with an RMS RLK status Otherwise the record is returned with one of the following statuses e RMS SUC No other writers e RMS OK RLK Record can be read but not written e RMS OK RRL Exclusive lock is held lock request denied but the read regardless RAB V_RRL option is set When only the RAB V_NLK option is specified record access can be denied When both the RAB V_NLK and RAB V_RRL options are specified an application can guarantee the return of any record with a success or alternate success status The OpenVMS Version 7 2 1H1 introduces the no query record locking option which allows applications to read records using GET or FIND services without any consideration of record locking This option e Does not make a call to the lock manager e Is equivalent to both RAB V_NLK and RAB V_RRL being set except that the RMS OK RLK or RMS OK RRL status will not be returned This functionality applies to all three file organizations sequential relative and indexed Three alternate methods for specifying the no query record locking option are outlined in Table 7 5 Note the following The first method allows the option to be enabled externally potentially wi
415. r RMS creates the file the application program must consider these record characteristics when storing retrieving and modifying records See Chapter 4 for information about creating files populating files with records and protecting files See Chapter 8 for information about record processing including record access modes synchronous and asynchronous record operations and retrieving inserting updating and deleting records The maximum size of an RMS file has no built in limitation other than the 32 bit virtual block number VBN In terms of blocks a single file is limited to a VBN that must be described in 32 bits So the maximum size of an RMS file is about 4 2 billion 4 294 967 295 blocks In terms of bytes this is equivalent to 2 terabytes 1 2 Disk Concepts This section describes disk concepts as an aid to understanding how a disk may be configured to enhance data access for improved performance Disk structures may be defined as either logical or physical and the two types interact with each other to some degree That is you cannot manipulate a logical structure without considering the effect on a corresponding physical structure RMS disk files reside on Files 11 On Disk Structure ODS disks Files 11 is the name of the disk structures supported by the operating system Files 11 disk structures are further characterized as being either on disk structures or CD ROM volume and file structures The Files 11 structure is a
416. r delimiter check use of Special characters 1 The only way to delete this file when the parsing style is TRADITIONAL is to use wildcards and for safety you should use the CONFIRM qualifier with the DELETE command However it is safer to change the parsing style to EXTENDED For example SSET PROCESS PARSE_STYLE EXTENDED SDELETE A B C 1 SSET PROCESS PARSE_STYLE TRADITIONAL 5 3 Logical Names and Parsing RMS translates a logical name present in a file specification at run time The use of logical names can be desirable for several reasons including program simplification device independence file independence and ease of use You can specify the file specification at compile or assembly time or the program can prompt for it at run time By specifying a logical name when you compile a program you eliminate having to program a terminal input request and you preserve the flexibility of being able to specify the input file at run time Locating and Naming Files on Disks 5 11 Locating and Naming Files on Disks 5 3 Logical Names and Parsing Device independence is more readily attainable if a logical name is used for the device name component By using a logical name rather than explicitly specifying a physical device an alternate device usually containing a recent backup copy of the device can be substituted by changing the definition of the logical name Typically device independence can reduce or eliminate the downtime ca
417. racter is to be used as part of a file name rather than as a character that has a special meaning in a file specification For the period and tilde the escape character is required only under some circumstances detailed in their respective footnotes Period l Comma Semilcolon Left bracket Right bracket Percent Circumflex Amperesand amp Exclamation point Pound sign Apostrophe Left parenthesis Right parenthesis Plus sign Atsign Grave accent Left brace l Right brace Equal sign Tilde 2 The escape character is required before a period in a directory name is optional before a period in a file name and must not be used for the period that delimits the file type A period is not permitted in a file type The tilde that is the leading character in a file name or directory may require an escape character 2 5 6 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 2 File Specification Components The following characters may be preceded by an escape but need not be on input to RMS Period l Dollar sign Minus sign Tilde 2 Sequences consisting of the escape character followed by any character not mentioned previously are reserved Spaces not preceded by the RMS escape character are removed from the specification by RMS on Alpha and VAX Note that the extended character set applies only to
418. ration fails the RFA is undefined Table 8 3 summarizes the effect that each successful record operation has on the context of the current record 8 6 2 Next Record Position RMS uses the next record position for doing sequential record access For sequential record processing the next record position is the location of the target record for the next Find service Get service where appropriate or Put service In a relative file the target record is the record that occupies the next nonvacant cell The ability to look ahead significantly decreases access time for sequential processing RMS uses its internal knowledge of file organization and structures to determine the next record position for each record service The Connect service initializes the next record position to one of the following locations e The first record in a sequential file or the first cell in a relative file The first record in the collated sequence of the specified key of reference in an indexed file e The end of a file on disk if the RAB L_ROP field RAB V_EOF option is set e The end of a write accessed ANSI magnetic tape file unless the FAB V_NEF option is set in the FAB L_FOP field In any record access mode the Get service establishes the next record position as either the next record or the next record cell in the file This is also true for the Find service in sequential access mode The Truncate service establishes the end of the file at the curr
419. rd streams A record stream is the access environment in which file records may be read written deleted or updated Important elements of the access environment are the current record position if any the access mode established for the current record the sequential next record position and the state of locks on other records in the file The Connect service creates a record stream and associates it with a file opened or created by the appropriate service The connection between a record stream and a file is explicitly terminated by the Disconnect service or is implicitly terminated by closing the file Record streams are connected to a file in one of three ways e Within one process or across several processes multiple FABs can be connected to a shared file One or more record streams may then be connected to each FAB This form of sharing is known as interlocked interprocess file sharing and is associated with reading or writing records not blocks e Within one process multiple record streams can be associated with one FAB to read and write records not blocks This form of sharing is known as multistreaming e Within one process or across several processes multiple FABs can be connected to a file One record stream RAB is connected to each FAB and users provide their own synchronization This form of file sharing is known as user interlocked interprocess file sharing User interlocked interprocess file sharing usually applies on
420. re of an RMS file ANALYZE RMS FILE imposes a hierarchical tree structure on the internal RMS file structure Each data structure in the file is a node with a branch for each pointer in the data structure The file header is always the root node Each of the three file organizations sequential relative and indexed has its own tree structure To examine a file you enter commands that move the current position to particular structures within the tree The utility displays the current structure on the screen Table 10 1 summarizes the ANALYZE RMS FILE commands Table 10 1 ANALYZE RMS FILE Command Summary Command Function AGAIN Displays the current structure again DOWN branch Moves the structure pointer down to the next level If the current node has more than one branch the branch keyword must be specified If a branch keyword is required but not specified the utility will display a list of possibilities to prompt you You can also display the list by specifying DOWN DUMP n Displays a hexadecimal dump of the specified block EXIT Ends the interactive session FIRST Moves the structure pointer to the first structure on the current level The structure is displayed For example if you are examining data buckets and want to examine the first bucket this command will put you there and display the first bucket s header HELP keyword Displays help messages about the interactive commands NEXT Moves the str
421. read locked record using the read locking option or the no locking option the accessing service returns a success status Typically an application program uses the read locking option when it wants the record to remain in a consistent state while reading the record but does not intend to modify the record 7 2 2 4 No Locking Query Locking The no locking option specifies that the requesting record stream does not want to lock the record This locking option permits the requesting record stream to have access to all locked records except for records that are locked for exclusive access It also permits other record streams to apply any type of lock to the record Using this option minimizes contention but unlike the no query record locking option does not avoid a call to the lock manager By implication a record stream that uses the no locking option can only access the record for reading When a record stream uses the no locking option to access a record the invoked service returns with the record unlocked Note that when a record stream selects the no locking option RMS momentarily locks the record to query whether or not the record is already locked by another record stream This is required in order to determine if access is allowed If the record is not locked the requesting service returns a completion status indicating a successful access If the record has an exclusive lock the access is denied and the requesting service returns a
422. reated e FDL AREA VOLUME e RMS XABS W VOL For the list of the run time options that are common to creating and opening a file see Chapter 9 4 36 Creating and Populating Files Creating and Populating Files 4 6 Summary of File Creation Options For more information about the options listed above see Chapter 2 For more detailed information about the programming aspects of these options refer to the OpenVMS Record Management Services Reference Manual Creating and Populating Files 4 37 5 Locating and Naming Files on Disks When creating or opening a file your program must identify it with an appropriate file specification Typically high level languages require a file specification argument for an OPEN statement that names a file being created or locates a file being opened The most direct way for an application to provide a file specification is to accept a complete specification from the user and to pass it to the OPEN statement Another way is to have the application program supply specifications to RMS so that RMS can combine these as defaults with a partial user specification to compose a fully qualified file specification Or to have RMS resolve a partial specification by searching the disk for an existing file that matches the specification This chapter describes the components that make up a complete file specification and how RMS is used to name and locate files on disks Chapter 6 describes in more det
423. ree file organizations but the deferred write option is restricted to use with relative and indexed files The record processing options include the multiple buffer option the read ahead option and the write behind option The multiple buffer option may be used with all three file organizations but the read ahead option and the write behind option may be used only with sequential files This section summarizes the options Section 3 3 through Section 3 5 describe the options in the context of tuning files For additional information about buffering see Chapter 7 3 2 2 1 Multiple Buffers When a program accesses a data file it transfers the file from disk into memory using I O units of blocks multiblocks or buckets The I O units are subsequently placed in memory I O buffers sized to be compatible with the I O units If you do not have enough buffers excessive I O transfers may degrade the performance of your application On the other hand if you have too many buffers performance may degrade because of an overly large working set As a rule however increasing the size and number of buffers can improve performance if the data read into the buffers will soon be processed and if your working set can efficiently maintain the buffers In fact changing the size and number of buffers is the quickest way to improve the performance of your application when you are processing localized data The optimum number of buffers depends on the organ
424. returns the address of the record access block RAB to let your program subsequently change RAB values Some RAB options are not available in FDL and can be set only by directly accessing RAB fields and subfields at run time To invoke options after record stream connection your program must have direct access to RMS control block fields using the address of the RAB and symbolic offsets into it 9 1 1 Using the Edit FDL Utility You can use the Edit FDL utility to specify run time attributes such as adding a CONNECT attribute that is used to set a control block value when the FDL PARSE and FDL RELEASE routines are called by your program These attributes preset the values available for opening a file and connecting a record stream Run Time Options 9 1 Run Time Options 9 1 Specifying Run Time Options The following original FDL file was created with the Edit FDL utility IDENT 19 JUL SYSTEM FILE RECORD AREA 0 AREA 1 KEY 0 Because the Edit FDL utility does not include run time attributes you must add them to the FDL definition You can specify run time attributes by specifying the ACCESS CONNECT and SHARING attributes For example if you want to add the CONNECT secondary attribute LOCK ON WRITE you use the EDIT FDL 1994 14 57 37 OpenVMS SOURCE ORGANIZATION CARRIAGE CONTROL FORMAT SIZE ALLOCATION BEST TRY CONTIGUOUS BUCKET SIZE EXTENSION ALLOCATION BEST TRY CONTIGUOUS BUCKET SIZE EXTENSI
425. ristics of a key in an indexed file including key size starting position key type bucket fill size and key options e FDL KEY attributes e RMS Key Definition XAB fields Defines the maximum number of records for the file Applies only to relative files e FDL FILE MAX RECORD NUMBER e RMS FABSL MRN Defines the maximum record size for all records in the file Maximum record size refers to the size of all records in a file with fixed length records the size of the largest record with variable length records or the size of the variable length portion of VFC records A value of 0 with variable length records means that there is no limit on the record size except for magnetic tape files for which a value of 0 sets an effective maximum record size equal to the block size minus 4 Variable length records and VFC records must conform to certain physical limitations see the OpenVMS Record Management Services Reference Manual e FDL RECORD SIZE e RMS FAB L_MRS Creating and Populating Files 4 33 Creating and Populating Files 4 6 Summary of File Creation Options Name of Option Function Record attributes Record format Defines the following control information for each record Records can use one of the following carriage control conventions Each record is preceded by a line feed and terminated by a carriage return FDL attribute RECORD CARRIAGE RETURN This is the default Each record contain
426. rocess is limited to reading and locating records it should have read access to the file If your process is deleting adding truncating or updating records it must have write access to the file RMS permits any process that may delete add truncate or modify records to also locate and read records because write access to a file also implies read access You can perform block I O operations using the Read Space and Write services Block I O is usually only used by applications written in VAX MACRO or other low level languages Note that when ACCESS BLOCK IO is specified the application program must also specify either SHARING USER INTERLOCK or SHARING PROHIBIT File Sharing and Buffering 7 3 File Sharing and Buffering 7 1 File Accessing Different types of record operations can be specified to define the type of access to be allowed for other processes as shown in Table 7 2 Table 7 2 File Sharing Record Operations Function Service FDL and RMS Options Read records Get SHARING GET specified or FAB B_SHR field FAB V SHRGET set Locate records Find SHARING GET specified or FAB B_SHR field FAB V SHRGET set Delete records Delete SHARING DELETE specified or FAB B_SHR field FAB V SHRDEL set Add new records Put SHARING PUT specified or FAB B_SHR field FAB V SHRPUT set Modify records Update SHARING UPDATE specified or FAB B FAC field FAB V SHRUPD set No access SHARING PROHIBIT or FAB B SHR field FABSV NIL set Us
427. rocesses the locked record When it finishes processing the record the application program calls the appropriate service to finish processing and unlock the record The following scenario illustrates processing an existing record 1 The application program invokes the Get service to access the record lock the record for exclusive access and return the record to the application program 2 The application program modifies the locked record Other record streams that try to access the record using default record locking get a record locked error This prevents the locked record from being accessed and modified before the application program finishes modifying it 3 The application program invokes the Update service to store the modified record in the file and remove the lock on the modified record thereby making the record available to other record streams When RMS provides record locking the Get Find and Put services apply locks The Get service and the Find service normally return with a record locked but the Put service returns with the record unlocked unless you specify the manual unlocking option When the application program uses default record locking RMS automatically unlocks the locked record when one of the following events occurs e Another record is accessed Get service and Find service e The current record is updated Update service e The current record is deleted Delete service e The record stream is disco
428. rom 4 29 calling FDL CREATE from 4 17 Command procedures 1 34 Completion status code field 5 25 Compound characters 5 6 Compound documents 4 19 Concurrent Access global section 7 24 Connect service 8 5 asynchronous operations and 8 19 effect on next record position 8 17 Contiguity 10 27 FAB and XAB fields 3 8 CONTIGUOUS attribute 3 24 4 35 Contiguous best try option 4 35 Contiguous best try request 3 8 Contiguous option 4 35 Contiguous request 3 8 CONTIN SYS file 1 10 Continuation files 1 10 CONTROL FIELD SIZE attribute 4 33 Convert Reclaim utility CONVERT RECLAIM 1 38 3 19 using with Prolog 3 files 3 20 10 28 Convert utility CONVERT 1 37 9 8 creating data files 4 15 4 16 making a file contiguous 10 28 populating a file 4 27 reorganizing files 10 28 reorganizing noncontiguous files 3 27 10 28 using with Prolog 3 files 3 20 with corrupted files 10 1 10 2 with FDL files 4 2 with Prolog 1 and Prolog 2 files 3 19 COPY command CONTIGUOUS qualifier 9 8 10 27 Core image file 1 10 CORIMG SYS file 1 10 Count field for variable length records 2 9 Create FDL utility CREATE FDL 1 39 4 2 4 16 maintaining files 10 1 Create if option 4 15 4 31 5 22 CREATE qualifier 4 10 Create service 4 15 5 22 for process permanent files 6 22 CREATE IF attribute 4 31 Creation date field 1 30 zero creation date 1 31 Creation time options con
429. rprocess file sharing allows one or more application programs to write records to a sequential file residing on a disk device or to a file on a disk device that is open for block I O processing It cannot be used with relative and indexed files opened for record access For record access to relative and indexed files RMS transparently controls the reading and writing of buffers to the file and always maintains current end of file information All sequential files that reside on disk devices may be write shared with user provided interlocks To use this feature you must specify SHARING USER INTERLOCK set the FAB B_SHR field FAB V UPI bit Note that when this option is specified RMS does not attempt to control the reading and writing of I O 7 6 File Sharing and Buffering File Sharing and Buffering 7 1 File Accessing buffers across processes nor does it maintain end of file information Thus you must use the Flush service or language equivalent if any to force the writing of modified I O buffers and to rewrite the record attributes including end of file information in the file header Processes that open the file after that point obtain the new end of file information Note also that record attributes are rewritten whenever a file is closed The last write accessor to close the file must also be the last accessor to have extended the file If not end of file information is written by another write accessor Read accessors of a shared
430. rue e OpenVMS RMS statistics have not been enabled e The file has not been opened or connected e A restriction listed previously in Section 3 6 has been ignored From the programming interface you can determine whether RMS statistics are enabled by using an appropriately configured XABITM You can interactively determine whether RMS statistics are enabled by using the DCL DIRECTORY FULL command If RMS statistics are enabled the DIRECTORY FULL display includes the following line RMS attributes File statistics enabled Note that RMS creates a global page file section when you initially open a file marked for statistics gathering Excessive use of statistics gathering might exhaust resources associated with global sections and if RMS cannot create the global page file section the OPEN service returns an error See the OpenVMS System Services Reference Manual A GETUAI for information about system parameters associated with global sections Performance Considerations 3 29 Performance Considerations 3 6 Monitoring RMS Performance See the OpenVMS DCL Dictionary for details about using the DCL interface to enable statistics gathering for a file The OpenVMS Record Management Utilities Reference Manual provides details about enabling RMS statistics for a file through the FDL interface Instructions for gathering RMS statistics through the program interface are provided in the OpenVMS Record Management Services Reference Manual 3 6
431. ry Consider an application made up of several programs that refer to the same file using a file specification IN INVENTORY FILE DAT Assume that all of the programs invoke the following command procedure to define the logical name IN as device DUA29 Advanced Use of File Specifications 6 17 Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concatenation ON CONTROL Y THEN GOTO ENDIT DEFINE IN DUA29 RUN XYZPROG ENDIT EXIT The programs show the current inventory level and the stockroom used for a particular item and are dispersed among many users in the company As the business grows the number of items in the inventory grows and the number of inventory records makes the file extremely large and difficult to access Because the items can be classified as belonging to one of four groups the data management department decides to split the file into four parts A special purpose program reads each record in the master file determines the record type and routes the record to the appropriate file group All output files are named FILE DAT but each is distinguished by putting it in a top level directory associated with the appropriate group category For example computer supplies files are cataloged in the directory COMPUTER INVENTORY This is done by modifying the command procedure to conditionally define the value of IN to be a rooted device logical name with four subdirectories The mod
432. ry and then resume working speed before the next record operation Each IRG is approximately 0 6 inch in length Writing an 80 character record at 1600 bpi requires 0 05 inch of space The IRG therefore requires twelve times more space than the data with a resultant waste of storage space RMS can reduce the size of this wasted space by using a record blocking technique that groups individual records into a block and places the IRG after the block rather than after each record A block on disk is different from a block on tape On disk a block is fixed at 512 bytes on tape you determine the size of a block However record blocking requires more buffer space for your program resulting in an increased need for memory The greater the number of records in a block the greater the buffer size requirements You must determine the point at which the benefits of record blocking cease based on the configuration of your computer system Figure 1 5 shows how space can be saved by record blocking Assume that a 1600 bpi tape contains 10 records not grouped into record blocks Each record is 160 characters long 0 1 inch at 1600 bpi with a 0 6 inch IRG after each record this uses 7 inches of tape Placing the same 10 records into 1 record block uses only 1 6 inches of tape 1 inch for the data records and 0 6 inch for the IRG 1 18 Introduction Introduction 1 3 Magnetic Tape Concepts Figure 1 5 Interrecord Gaps Without Record Blocking
433. ry locking To update or delete a record a record stream must have an exclusive lock or a write lock on the record 7 2 2 1 Exclusive Locking By default RMS performs exclusive locking With exclusive locking only the initial record stream is permitted to access the record for reading or writing until the lock is released Any other record stream that tries to read or write the record by applying a lock is denied access When a record stream is denied access because of a locked record the requesting service returns a locked record status RMS _RLK A record stream can read an exclusively locked record only with the read regardless option see Section 7 2 3 3 Most application programs use exclusive locking because it requires minimal programming and provides maximum protection when modifying and reading records Note however that contention is apt to be greatest when a record stream uses the exclusive locking option See Section 7 2 1 for an example of how RMS uses exclusive locking for an application program that is modifying a record 7 2 2 2 Write Locking The write locking option allows the record stream that locks a record to modify the record This option prohibits other record streams from having write lock access or exclusive lock access both of which imply an intent to modify the record The write locking option also denies read lock access to other record streams because a read lock access is incompatible with a record s
434. s 0 0 0 0 cece eee eee pensi 2 2 1 Sequential File Organization 000s 2 2 2 Relative File Organization 0 0 ccc cece eee eee 2 2 3 Indexed File Organization 0 0 00 cece eee 2 2 3 1 Sequentially Retrieving Indexed Records 2 2 3 2 Index Keys ra 5 2o ovest tev alan oe awed ae a Bae ears 2 2 3 3 Other Key Characteristics llle 2 2 3 4 Specifying Sort Order seess sers han epee ee o 2 2 3 5 Using Collated Keys elles 2 2 3 6 Summary of Indexed File Organization 4 3 Performance Considerations 3 1 Design Considerations ses ressens da tarr EENI EEES EERI VEES EENIA 3 1 1 Peed cie vues ua GERM Pe RC ER TEN GNDERESIUS S RR E TU etre 3 1 2 PACH wana Ge pere E NE cm Em pb aa ed d red S 3 1 3 Shared ACCESS auos eso doce kerd t howe ww doa Res i pue does Enhi 3 1 4 Impact on Applications Design llle 3 2 UTS osse oe yc eom x SOR ae CHOR Dope HOS De ear Oe oes 3 2 1 File Design Attributes llle 3 2 1 1 Initial File Allocation 252 2 rr RR yy 3 2 1 2 Contig lly 5 2242 22449 ter EEr errr ebrea ETE E ES 3 2 1 3 Extending a File 3 ose sch ee irt rins Ss Rcx RR OS NUR CP CR Oe C 3 2 1 3 1 Auto Extend Size Selection 0 00 3 2 1 3 2 Establishing Auto Extend Default Quantities 3 2 1 3 3 Placement and Contiguity of Extends LL 3 2 1 4 Truncating File n gs5 24 ack waa br Peed Ok NEE EE ORES
435. s RMS currently supports three distinct prologs Prolog 1 Prolog 2 and Prolog 3 but RMS normally creates a Prolog 3 indexed file However you can specify a previous prolog version typically for compatibility with RMS 11 2 2 3 4 Sequentially Retrieving Indexed Records To sequentially retrieve indexed records your program must specify the key for the first access RMS then uses the index for that key to retrieve successive records For example assume an index file with three records having primary keys of A B and C respectively To retrieve these records sequentially in ascending sort order your program must provide the key A on the first access RMS accesses the next two records without further key inputs from your program To randomly retrieve records in an index file your program must provide the appropriate key value for each access Now assume an index file with three records having primary keys A B and C that are retrieved in C A B order On the first access your program must provide the key C on the next access the key A and on the final access the key B Choosing a File Organization 2 19 Choosing a File Organization 2 2 File Organization Concepts 2 2 3 2 Index Keys In an indexed file each record includes one or more key fields or simply keys that RMS uses to build related indexes Each key is identified by its location its length and whether it is a simple or a segmented key A simple key may be any one of
436. s a Fortran carriage return FDL attribute RECORD FORTRAN Each record is in print format where the two byte fixed length control field VFC record format of each record contains the carriage return information FDL attribute RECORD PRINT No carriage control provided FDL attribute RECORD NONE Records can be prevented from crossing block boundaries FDL attribute RECORD BLOCK SPAN For variable length records the byte count field may be formatted in LSB least significant byte format default or in MSB most significant byte format FDL attribute RECORD MSB RECORD LENGTH FDL RECORD BLOCK SPAN RECORD MSB_ RECORD LENGTH RMS FAB B RAT Defines the record format Fixed length record format Variable length record format VFC record format Stream record format Undefined record format sequential files only FDL RECORD FORMAT RMS FAB B RFM 4 6 3 File Allocation and Positioning You can specify file allocation and positioning options with either the FAB control block or an allocation XAB XABALL control block Note that any value specified in the XABALL control block overrides the corresponding value in the FAB The creation time options described in the following table apply to file allocation and positioning 4 34 Creating and Populating Files Creating and Populating Files 4 6 Summary of File Creation Options Name of Option Function Allocation quantity Areas Contiguous
437. s of each section are written consecutively in ascending order section n 1 is written immediately following section n file sections of other files are not interspersed Each of the file and volume configurations is illustrated in the sections that follow Introduction 1 23 Introduction 1 3 Magnetic Tape Concepts 1 24 Figure 1 7 Single File on a Single Volume e er voL HR HDRe HORS mM First File Scratch EOF1 EOF2 EOF3 Tape ZK 0346 GE Single File Residing on a Single Tape Volume A single file on a single tape volume configuration consists of one file on one volume The components of the ANSI magnetic tape format for this configuration are illustrated in Figure 1 7 Single File Requiring Multiple Tape Volumes A single file multivolume configuration consists of one file that spans two or more volumes in a volume set Figure 1 8 illustrates the components of the ANSI magnetic tape format for this configuration Multiple Files on a Single Tape Volume A multifile single volume configuration consists of two or more files on a single volume It is the most common file and volume configuration Figure 1 9 illustrates the components of the ANSI magnetic tape format for this configuration Multifile Multivolume Configuration A multifile multivolume configuration consists of two or more files that span two or more volumes in the same volume set Figure 1 10 illustrates the components of the ANSI
438. s of mean size If you do not allow block spanning the Edit FDL utility factors in the potential wasted space at the end of each block For relative files the Edit FDL utility calculates the total number of buckets in the file and then allocates enough blocks to hold the required number of buckets and associated overhead The Edit FDL utility calculates the total number of buckets by dividing the total number of records in the file by the bucket record capacity The overhead consists of the prolog which is equal to one block and is stored in VBN 1 For indexed files the Edit FDL utility calculates the depth to determine the actual bucket size and number of buckets at each level of the index It then allocates enough blocks to hold the required number of buckets Areas for the data level Level 0 have separate allocations from the areas for the index levels of each key In all cases allocations are rounded up to a multiple of bucket size A 2 Extension Size For sequential files the Edit FDL utility sets the extension size to one tenth of the allocation size and truncates any fraction For relative files and indexed files the Edit FDL utility extends the file by 25 percent rounded up to the next multiple of the bucket size A 3 Bucket Size Because most records that the Edit FDL utility accesses are close to each other it makes the buckets large enough to hold 16 records or the total record capacity of the file whichever is smaller
439. s only written to disk after it is completely filled Deferred write processing is a default run time option for some high level languages and can be specified by using clauses in other languages You can activate this option through FDL by adding the FILE attribute DEFERRED_ WRITE From a low level language you can activate the deferred write option by setting the FAB V_DFW bit in FAB L_FOP field 3 2 2 3 Global Buffers If several processes are to share a file you may want to provide the file with global buffers l O buffers that two or more processes can access With global buffers processes may access file information without allocating dedicated buffers If you do not allocate dedicated buffers you can conserve buffer space and buffer management overhead You gain this benefit at the cost of additional system resources as described in the OpenVMS Record Management Services Reference Manual When you create a file you can assign the desired number of global buffers by using the FDL editor to set the value for the FILE secondary attribute GLOBAL BUFFER COUNT From a low level language you can optionally set the value directly into the FAB W_GBC field Alternatively you may use the DCL command SET FILE GLOBAL BUFFERS to set the global buffer count Global buffers are not used directly to retain modified information when the deferred write option is enabled If a global buffer is modified and the deferred write option is enabled th
440. s the next record position as the location of the first record for the current key of reference Any unsuccessful record operation has no effect on the next record 8 7 Synchronous and Asynchronous Operations Your program can handle record operations on a file in one of two ways synchronously or asynchronously When operating synchronously the program issuing the record operation request regains control only when the request is completely satisfied Most high level languages support synchronous operation only In asynchronous operations the program can regain control before the request is completely satisfied You can specify record operations and file operations to be either synchronous or asynchronous for each record stream For instance when reading a record from a file synchronously the program regains control only after the record is passed to the program In other words the program waits until the record returns no other processing for this program takes place during this read and return cycle On the other hand when reading a record asynchronously the program might be able to regain control before the record is passed to the program The program can thus use the time normally required for the record transfer between the file and memory to perform some other computations Another record operation cannot be started on the same stream until the previous record operation is complete However record operations on other streams can be i
441. s the program to specify access semantics with the Connect service RMS returns the file attributes including the stored semantics attribute tag value to the program as part of the Open service When the program subsequently invokes the Connect service RMS uses the specified operations mode to determine its response If the program specified FAB V BRO with the Open service and then specifies block I O RAB V BIO when it invokes the Connect service RMS does not associate the RMS extension with the file access But if the program specifies record access or FAB V_BRO when it opens the file and then decides to use record I O when it invokes the Connect service RMS compares the access semantics with the file s stored semantics to determine whether to associate the RMS extension with the file access If the access semantics match the stored semantics RMS does not associate the RMS extension with the file access If the access semantics do not match the stored semantics RMS associates the RMS extension with the file access In this case the program must use the Display service to obtain the modified file attributes If RMS cannot find the appropriate RMS extension the operation fails and the Connect service returns the EXTNOTFOU error message If the application program senses the file s stored semantics RMS allows mixed mode operations In this case mixed block and record operations are permitted because the application gets record mode fi
442. s with leading hyphens Although you can create files with such names it is not recommended because access to the files will be limited to a subset of otherwise supported functions In addition remember that in a mixed cluster environment although such files can be created and accessed from a Version 7 2 Alpha cluster member they are not fully accessible from all of the other cluster members 5 2 9 Restrictions and Anomalies The following sections describe a restriction when using extended file names and a DCL parsing anomaly 5 2 9 1 Restriction with Extended File Names Using the tilde as the first character in a file name in the Compaq C Run Time Library CRTL allows a programmer to specify both UNIX style and OpenVMS style file specifications to routines such as creat and fopen In UNIX file specifications a tilde in the first character of a pathname represents the user s home directory However in an OpenVMS extended file name a tilde is legal anywhere in a file name or directory name To preserve backward compatibility the CRTL will continue to interpret a leading tilde to mean the user s home directory To pass an OpenVMS file name that begins with a tilde to a CRTL routine that accepts UNIX style file specifications specify the tilde preceded by the escape character For example 5 10 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 2 File Specification Components
443. segmented primary keys but the segments cannot overlap If you want to use a Prolog 3 file in this case consider defining the overlapping segmented key as an alternate key and choosing a different key to be the primary key If you want to use overlapping primary key segments you must use a Prolog 2 file If record deletions result in empty buckets in Prolog 3 files you can use the Convert Reclaim utility to make the buckets usable again Because CONVERT RECLAIM does not create a new file RFAs remain the same Note that RMS 11 does not support Prolog 3 files To use a Prolog 3 file with RMS 11 you must first use the Convert utility to transform the file into a Prolog 1 file or into a Prolog 2 file 3 5 1 2 Primary Index Structure The primary index structure consists of the file s data records and a key pathway based on the primary key key 0 The base of a primary index structure is the data records themselves arranged sequentially according to the primary key value The data records are called level 0 of the index structure The data records are grouped into buckets which is the I O unit for indexed files Because the records are arranged according to their primary key values no other record in the bucket has a higher key value than the last record in that bucket This high key value along with a pointer to the data bucket is copied to an index record on the next level of the index structure known as level 1 The index records ar
444. ses the record lock Any other record stream that tries to access the cell to put data into it receives a record locked status RMS RLK If the record stream that has the lock puts a record into the cell RMS returns an alternate success status RMS OK ALK indicating that the cell was already locked In general the RMS OK ALK status is returned when a service tries to lock a record that the current record stream has already locked This also applies to the Put service which locks and unlocks the record in one record operation The next table lists miscellaneous record locking options and how you select each option through the FDL and RMS interfaces Option Interface How to Select Manual unlocking FDL CONNECT MANUAL UNLOCKING RMS RAB L ROP RAB V ULK Lock nonexistent record FDL CONNECT NONEXISTENT RECORD RMS RAB L ROP RAB V NXR 7 2 5 Record Locking Deadlocks A deadlock occurs when there is a set of processes and each process is waiting to access a record that is locked by another process in the set The program stalls because none of the processes can acquire the record that it needs to complete its task and release its locks 7 16 File Sharing and Buffering File Sharing and Buffering 7 2 Record Locking The lock manager resolves the deadlock by denying one of the lock requests When this occurs with a record lock RMS returns an RMS DEADLOCK status The RMS DEADLOCK status is only returned if the wait if locked o
445. sharing and file access Typically the initial accessor denies all write access to subsequent processes Such a restriction occurs when the initial accessor specifies some type of write access for file access without specifying write access for file sharing If the initial accessor specifies read only file access and file sharing subsequent accessors can only read the file If the appropriate type of write access is not specified then subsequent accessors cannot perform the corresponding write operations to the file If the initial accessor specifies one or more values for file sharing subsequent processes can access the file if they specify compatible file access values For example if the initial accessor specifies SHARING GET and SHARING PUT subsequent accessors must specify ACCESS GET to read the file and ACCESS PUT to write new records to the file read access is implied by all four types of write access Table 7 3 presents the values that the initial accessor of a file can specify for file sharing to permit access to subsequent accessors File Sharing and Buffering 7 5 File Sharing and Buffering 7 1 File Accessing Table 7 3 Initial File Sharing and Subsequent File Access Initial Accessor Sharing Subsequent Accessor Access SHARING PROHIBIT No access allowed SHARING GET ACCESS GET SHARING DELETE ACCESS DELETE SHARING PUT ACCESS PUT SHARING UPDATE ACCESS UPDATE 1Implied related operation Because the i
446. st specify a year before 1900 If you specify a binary zero in the date field the system will write the current date to the field For details on the XABDAT see the OpenVMS Record Management Services Reference Manual Accessibility Field The contents of this field are described in Section 1 3 1 5 Implementation Identifier Field The implementation identifier field specifies using ASCII a characters an identification of the implementation that recorded the Volume Header Label Set 1 3 1 6 2 HDR2 Label The HDR2 label describes the record format maximum record size and maximum block size of a file Record Format Field The record format field specifies the type of record format the file contains The operating system supports two record formats fixed length F and variable length D When files contain record formats that the system does not support it cannot interpret the formats and classifies them as undefined Fixed length records are all the same length No indication of the record length is required within the records because either the HDR2 label defines the record length or you specify the record length with the RECORDSIZE qualifier A fixed length record can be a complete block or several records can be grouped together in a block Fixed length blocked records are padded to a multiple of 4 records Variable length records are padded to the block size If a block is not filled it will be padded with circumflex charac
447. ster or more efficiently and then reorganizing the file to reflect those changes There are two ways to tune files You can redesign your FDL file to change file characteristics or parameters You can change these characteristics either interactively with the Edit FDL utility the preferred method or by using a text editor With the redesigned FDL file then you can create a new data file You can also optimize your data file by using ANALYZE RMS FILE with the FDL qualifier This method rather than actually redesigning your FDL file produces an FDL file containing certain statistics about the file s use that you can then use to tune your existing data file Figure 10 8 shows how to use the RMS utilities to perform the tuning cycle 10 24 Maintaining Files Maintaining Files 10 3 Optimizing and Redesigning File Characteristics Figure 10 8 RMS Tuning Cycle Indexed Data File ANALYZE RMS FILE FDL File with ANALYSIS Sections EDIT FDL Original FDL File FDL File Revised CONVERT Tuned Indexed Data File ZK 0952 GE Section 10 3 1 describes how to redesign an FDL file and Section 10 3 2 explains how to optimize the run time performance of a data file 10 3 1 Redesigning an FDL File There are many ways to redesign an FDL file If you want to make small changes you can use the ADD DELETE and MODIFY commands at the main menu main editor level Maintaining Files 10 25 Main
448. stics e Section 4 2 describes how to create a file e Section 4 3 describes how to create and access tagged files e Section 4 4 explains how to define file protection e Section 4 5 describes how to populate the file e Section 4 6 provides a summary of the options related to file creation 4 1 File Creation Characteristics You can specify the characteristics you need to create a file in two ways If you use VAX MACRO or BLISS 32 you can specify file characteristics by including OpenVMS RMS hereafter referred to as RMS control blocks in your application program If you use a high level language you can use the File Definition Language FDL a special purpose language that is used to write specifications for data files Of course you also have the option of using FDL with VAX MACRO or BLISS 32 The following sections describe how you can specify file creation characteristics by using RMS control blocks or by creating FDL files 4 1 1 Using RMS Control Blocks You can establish characteristics for the file you create by using an RMS file access block FAB and extended attribute blocks XABs These control blocks allow you to take the defaults that RMS provides or to override the defaults and define the characteristics that suit your particular application 4 1 1 1 File Access Block The FAB is made up of fields that describe various file characteristics and contain the following file related information e The addresses of
449. systems and ODS 5 disks includes enhanced support for the use of file names and subdirectory and root subdirectory names It supports all possible 8 bit characters excluding only the following two characters VES Note that the character set includes both the ISO Latin 1 C1 character set hexadecimal 80 9F as well as graphical and other characters between 9F and FF This allows the entire ISO Latin 1 character set with the exclusions noted above In addition there is support for names that include any of the defined 16 bit Unicode characters except for the character exclusions noted above 5 4 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 2 File Specification Components 5 2 4 RMS and On Disk Representation The extended character set includes characters that have special significance to RMS for example delimiters such as that have significance to DCL for example the comment character and that cannot be easily entered or displayed via keyboards and display devices that are commonly available for example the Unicode characters and the ISO Latin 1 C1 control characters To accommodate the use of these characters RMS accepts and displays them in a format that uses a sequence of common ASCII characters to represent a single one of these special characters These sequences are known as compound characters For example the sequence of six simple characters U1234 comprise a compound char
450. t OpenVMS Cluster performance if you allow your applications to become I O bound The Monitor utility is a good tool for estimating how many I O requests your application generates For more information about the Monitor utility see the OpenVMS System Manager s Manual Performance Considerations 3 33 Performance Considerations 3 7 Processing in an OpenVMS Cluster Environment e Process files with exclusive access to obtain better performance than processing files with shared write access Opening files for unnecessary shared write access incurs needless locking cost even on a single node system e If possible confine your application to a single CPU If sufficient CPU resources and I O capacity are available your application performs faster than if it was spread over many nodes e Provide for sufficient memory because the space overhead for the lock database and other system software can be significant 3 34 Performance Considerations 4 Creating and Populating Files After you have designed your file you need to create it First you must specify the file characteristics you selected during the design phase Then you need to create the actual file with those characteristics and to protect it decide who has access to the file Lastly you need to put records in the file or populate it This chapter describes the process of creating and populating files e Section 4 1 tells how to select and specify file creation characteri
451. t and Content for SEQ DAT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 85 36 37 38 39 40 41 42 ZK 0737 GE 10 12 Maintaining Files Maintaining Files 10 1 Viewing File Characteristics Example 10 3 Examining a Sequential File ANALYZE RMS FILE INTERACTIVE SEQ DAT FILE HEADER File Spec DISKSDELPHIWORK RMS32 SEQ DAT 3 File ID 1170 2 2 Owner UIC 730 465 Protection System RWED Owner RWED Group RWED World Creation Date 7 MAY 1993 16 51 30 92 Revision Date 8 MAY 1993 14 02 17 15 Number 3 Expiration Date none specified Backup Date none posted Contiguity Options none Performance Options none Reliability Options none ANALYZE DOWN RMS FILE ATTRIBUTES File Organization sequential Record Format variable Record Attributes carriage return Maximum Record Size 0 Longest Record 73 Blocks Allocated 3 Default Extend Size 0 End of File VBN 1 Offset X 00E4 File Monitoring disabled Global Buffer Count 0 ANALYZE DOWN DATA BYTES VBN 1 offset X 0000 7 65 4 3 21 0 01234567 31 30 30 30 30 30 00 49 0000 1 000001 20 4C 41 54 49 47 49 44 0008 COMPAQ 4E 45 4D 50 49 55 51 45 0010 COMPUTER 52 4F 50 52 4F 43 20 54 0018 CORPORAT 31 31 20 4E 4F 49 54 41 0020 ION 110 42 20 54 49 50 53 20 30 0028 SPIT BRO 41 4F 52 20 4B 4F 4F 52 003
452. t and moves the remaining records to a newly created bucket Excessive bucket splitting can degrade system performance through wasted space excessive processing overhead and file fragmentation For example each record that moves to a new bucket must maintain a forward pointer in the original bucket The forward pointer indicates the record s new location At the new bucket the record must maintain a backward pointer to its original bucket RMS uses the backward pointer to update the forward pointer in the original bucket if the record later moves to yet another bucket When a program attempts to access a record either by alternate key or by RFA it must first go to the bucket where the record originally resided read the pointer to the record s current bucket residence and then access the record To avoid bucket splits you should permit buckets to be only partially filled when records are initially loaded This provides your application with space to make additional random inserts without overfilling the affected bucket Section 3 5 2 2 describes fill factors in more detail 3 10 Performance Considerations Performance Considerations 3 2 Tuning 3 2 2 Processing Options Five processing options can be used to improve I O operations two file processing options and three record processing options The file processing options include the deferred write option and the global buffer option The global buffer option may be used with all th
453. t definition MODIFY Allows you to change an existing line in the FDL definition When you issue the MODIFY command at the main menu level the Edit FDL utility prompts you with a menu displaying the current primary attributes of your FDL file When you type in a primary attribute the Edit FDL utility displays all the existing secondary attributes for that primary attribute with their current values You can then select the secondary attribute of which you want to change the value and then supply the appropriate value for the secondary attribute However if you want to make substantial changes to an FDL file you should invoke the Touch up script Because sequential and relative files are simple in design the Touch up script works only with FDL files that describe indexed files If you want to redesign sequential and relative files you can use the command listed above ADD DELETE or MODIFY or you can go through the design phase again using the scripts for those organizations To completely redesign an existing FDL file that describes an indexed sequential file use the following command syntax EDIT FDL SCRIPT TOUCHUP fdl filespec 10 3 2 Optimizing a Data File To improve the performance of a data file use a 3 step procedure that includes analysis FDL optimization and conversion of the file If used periodically during the life of a data file this procedure yields a file that performs optimally For the analysis use the A
454. t string h gt include lt rms h gt include lt starlet h gt define MAXLINE 256 static int rms status RMS status variable static char ibuf MAXLINE input buffer obuf MAXLINE output buffer fbuf MAXLINE filename buffer xbuf MAXLINE expanded filename buffer struct FAB filfab FAB for SPARSE and SSEARCH struct NAM filnam NAM for SPARSE and SSEARCH void init Initialize RMS structures filfab cc rms fab Get a FAB filfab fab 1 fna ibuf Parse filename from IBUF filfab fab b fac FABSM GET Only allow GETs filfab fab l fop FABSM NAM Use the NAM block for filename filfab fab 1l nam amp filnam gt NAM block filnam cc rms nam Get a NAM block filnam nam 1 esa xbuf gt Expanded filespec buffer filnam nam b ess 255 Expanded filespec buffer length filnam nam l rsa fbuf Resultant filespec buffer filnam nam b rss 255 Resultant filespec buffer length main auto FILE fil File pointer for file functions auto int i Generic loop variable init Initialize RMS structures Get filespec to search fputs File stdout if gets ibuf return Validate filespec filfab fab b fns strlen ibuf if rms status sys parse amp filfab amp STS M SUCCESS 0 return rms status Get search string fputs String stdout if gets
455. taining Files 10 3 Optimizing and Redesigning File Characteristics Command Function ADD Allows you to add one or more new lines to the FDL file When you give the ADD command at the main menu level the Edit FDL utility prompts you with a menu displaying all legal primary attributes your FDL file does not necessarily have to contain all these attributes You can add a new primary attribute to your file or you can add a new secondary attribute to an existing primary attribute When you type in a primary attribute the Edit FDL utility displays all the legal secondary attributes for that primary attribute with their possible values You can then select the secondary attribute that you want to add to your FDL file and supply the appropriate value for the secondary attribute DELETE Allows you to delete one or more lines from the FDL file When you give the DELETE command at the main menu level the Edit FDL utility prompts you with a menu displaying the current primary attributes of your FDL file When you select the primary attribute for the attribute you want to remove from your FDL definition the Edit FDL utility displays the current values for all of the FDL file s secondary attributes When you select the appropriate secondary from this list the Edit FDL utility removes it from the FDL definition If you delete all of the secondary attributes of a primary attribute the Edit FDL utility removes the primary attribute from the curren
456. te if option it is especially important to specify the access and sharing values In this instance you have denied yourself access if the file already exists because you have specified SHARING NONE and you are not the initial accessor One way to avoid this when you create a file is to allow most operations for other users such as SHARING GET SHARING PUT SHARING UPDATE and SHARING DELETE Combinations of file access and file sharing that specify a mixture of interlocked interprocess file access and user interlocked interprocess file sharing allow the application program to access the file without record locking protection Such combinations are not recommended for general use they should be used only for application programs that require read only access to a file Other combinations may cause an error such as requesting ACCESS BLOCK IO without specifying SHARING NONE or SHARING USER INTERLOCK 7 1 2 Interlocked Interprocess File Sharing Interlocked interprocess is the most common form of file sharing This method allows the connection of one or more record streams RABs to one or more processes FABs either within a single process or across several processes When using this form of file sharing the values specified for file sharing and file access by the initial accessor determine the type of access permitted for subsequent processes The initial accessor must consider the restrictions that result from the values specified for file
457. te service or equivalent language statement removes a record from the file You cannot use this service for sequential files however a sequential file can be truncated using the Truncate service Like the Update service the Delete service must be preceded by a Find or Get service to establish the current record position The options associated with the Delete service are summarized in the following table These options can be set for each Delete service if the program can access the appropriate RAB control block fields The RAB control block fields are preset by connect time values or defaults and as a result of previous service calls Option Description Asynchronous record processing Fast delete Specifies that record I O for this record service will be asynchronous e FDL CONNECT ASYNCHRONOUS e RMS RAB L_ROP RAB V_ASY Specifies that the record to be deleted is flagged as deleted but parts of any alternate index key path are not completely erased until a subsequent access using the alternate key occurs This makes deleting the record occur more quickly but it requires additional access time for a subsequent Find or Get service e FDL CONNECT FAST_DELETE e RMS RAB L_ROP RAB V_FDL Run Time Options 9 21 Run Time Options 9 4 Run Time Example 9 4 Run Time Example Example 9 2 shows how to invoke the FDL PARSE and FDL RELEASE routines to use the predefined control block values set by an Edit FDL utilit
458. tem service Multistreaming allows your process to access the same file using more than one record stream and allows other users to access the file using interlocked interprocess file sharing unless SHARING PROHIBIT is also specified When you select this option select the appropriate SHARING record operations such as SHARING GET When multiple streams are connected the buffers allocated for each stream become part of a buffer cache for the entire process A buffer cache is a common shared buffer pool intended to minimize I O A record operation on one stream may use cached buffers from a previous record operation on a different stream that referenced the same buckets 7 4 File Sharing and Buffering File Sharing and Buffering 7 1 File Accessing When you open or create a file you must specify the file access and file sharing you want for it When using FDL or RMS the default is to read records from the file ACCESS GET and to allow others accessors to read records from the file SHARING GET Typically an application program may want to read records ACCESS GET while allowing other accessors to add records SHARING PUT You might want to modify records ACCESS UPDATE while allowing other accessors to add new records to the file SHARING PUT When you create a file the default is for FDL and RMS to add records to the file ACCESS PUT and to not allow others to access the file SHARING NONE When you create a file with the crea
459. teractive user enters Because LIB FIND FILE is used with the supplied arguments the file specification may contain wildcard characters a search list and a search list that assumes the program will allow the use of sticky defaults as in DCL command line parsing The routine is called by the following VAX BASIC program USEROPEN option for the BASIC OPEN statement 100 MAP REC 1 SURNAMES 20 RESTS 60 110 OPEN FOR OUTPUT AS FILE 1 ORGANIZATION RELATIVE amp MAP REC 1 USEROPEN LOCATE 120 CLOSE 1 130 END The BASIC program allocates the control blocks before control is given to the USEROPEN routine it also passes the address of the FAB as the first argument and the address of the RAB as the second argument These arguments enable the VAX MACRO routine to obtain the control block addresses because the argument pointer points to the longword count of arguments followed by the longword length arguments Because the VAX MACRO macros FAB and NAM are not used access to the symbolic offset values defined for these control blocks is not available thus the FABDEF NAMDEF and RABDEF macros define these symbols for the USEROPEN routine In addition to locating the file using any valid file specification the called routine also connects to the file requesting 15 global buffers or as many global buffers as system resources permit This routine is linked with the BASIC program to form the executable image Example 5 2 s
460. ters The standard does not allow records containing only circumflexes the system will interpret this as padding not data Figure 1 11 shows a block of fixed length records Each record has a fixed length of 50 bytes All six records are contained in a 300 byte block The records are blocked that is grouped together as one entity to increase processing efficiency when records are blocked you can access many of them with one I O request The block size should be a multiple of the record size Introduction 1 31 Introduction 1 3 Magnetic Tape Concepts Figure 1 11 Blocked Fixed Length Records Rec Rec Rec Rec Rec Rec 50 Bytes 50 Bytes 50 Bytes 50 Bytes 50 Bytes 50 Bytes Block 300 Bytes ZK 0353 GE The size of a variable length record is indicated by a record control word RCW The RCW consists of four bytes at the beginning of each record A variable length record can be a complete block or several records can be grouped together in a block Two variable length records are shown in Figure 1 12 The first consists of 54 bytes including the RCW The second consists of 112 bytes including the RCW The records are contained in a 166 byte block Do not use system dependent record formats on volumes used for information interchange OpenVMS system dependent formats are stream and variable with fixed length control VFC Figure 1 12 Variable Length Records Record Size 54 Bytes Record Size 112 Bytes Pad
461. tes the use of global buffers 7 22 File Sharing and Buffering File Sharing and Buffering 7 3 Local and Shared Buffering Techniques Figure 7 3 Using Global Buffers for a Shared File Process A Process B System Virtual Memory Global Buffer Cache Blocks or Buckets e Unlike local buffers global buffers can be accessed by multiple processes accessing the same file When a record requested by one process is located in a global buffer the record can be transferred directly from the global buffer to the program eliminating an I O read operation Note that if the previous accessor modified the record RMS writes the buffer to disk before returning the record to the new accessor This ensures that the modified bucket in memory matches its counterpart on the disk Process Process l ZK 1994 GE There are two situations in which global buffers cannot be used for shared files When a process permanent file is being accessed RMS does not use global buffers no error is returned When an image is linked using the LINK option keyword IOSEGMENT NOPOBUFS rarely used RMS does not use global buffers Even if global buffers are used a minimal number of local buffers should be requested because under certain circumstances RMS may need to use local buffers When attempting to access a record RMS looks first in the global buffer cache for the record before looking in the local buffers if the record is still
462. the overhead of having to move the file several times 6 3 3 Using Rooted Directory Syntax Rooted directory syntax provides a way of making a directory or subdirectory appear to the user as the master file directory MFD for the logical disk volume Subdirectories of the rooted directory appear as top level directories user file directories for the logical volume The root directory is the directory you specify during logical name definition that serves as a base from which you can access the directories beneath it Note Octal group and member directory designations for example 1 4 are not allowed in rooted directories A concealed device logical name that defines a hidden root directory is called a rooted device logical name When you define the rooted device logical name for use in a program in a SET DEFAULT command you specify that the logical name is a concealed device logical name by using the TRANSLATION_ATTRIBUTES CONCEALED qualifier with the DCL command DEFINE or ASSIGN To define the concealed device logical name as a rooted device logical name the root directory must contain a trailing period such as DUA22 ROOT When specifying a directory you can only use a trailing period for the root directory 6 14 Advanced Use of File Specifications Advanced Use of File Specifications 6 3 Directory Syntax Conventions and Directory Concatenation When you define a root directory all directory references ref
463. the DSI contains OpenVMS file and record information you should insert nulls in the record information fields immediately preceding the DSI The following three fields contain record information e Record format in byte position 79 e Record attributes in byte position 80 e Record length in byte positions 81 to 84 If the DSI file identifier field DSI FILE_SYSTEM_IDENTIFIER contains a 0 and the DSI file version field DSISFILE SYSTEM VERSION contains either a 1 or a 2 use the area immediately following the DSI to obtain OpenVMS file and record information See B Figure 1 4 If the DSI file version field contains a 1 the area immediately following the DSI contains a binary hex encoded file attributes block that provides file and record information See C Figure 1 4 If the DSI file version field contains a 2 the area immediately following the DSI contains an ASCII hex encoded byte stream that provides file and record information See D in Figure 1 4 When the DSI file version field contains a 0 the area immediately following the DSI will not contain file and record information Nevertheless if the media is mounted for DSI protection the OpenVMS UIC codes and permission codes for system owner group and world SOGW users will be enforced 1 16 Introduction Figure 1 4 DSI and FAT Structures in an XAR Introduction 1 2 Disk Concepts
464. the MTAACP process reads writes and interprets ANSI labels before passing this information to RMS and QIO system services These services in turn read write and interpret the record format of the data written in the file section 1 3 1 3 Basic Components of the ANSI Magnetic Tape Format 1 20 The format of ANSI magnetic tape consists of the following basic components e Beginning of tape BOT and end of tape EOT markers e Tape marks e File sections e Volume header and trailer labels Figure 1 6 displays the arrangement and function of these components Introduction Introduction 1 3 Magnetic Tape Concepts Figure 1 6 Basic Layout of an ANSI Magnetic Tape Volume pe Beginning of Tape TR Marker BOT Marks beginning of writable area on a volume Volume Label T VOL1 Identifies the volume HDR 1 HDR2 HDB Describes and delimits each file Tape Mark TM Separates header labels from file section Contains user data Data in volumes interchanged to File Section non VMS systems must be ASCII a characters Data in volumes interchanged to VMS systems can be in binary form Tape Mark TM Separates file section from trailer labels r Describes and delimits files When a volume is continued COR EOEZ EOFS EOV labels are written instead of EOF labels EOF3 i or EOVS labels are written only when a HDR3 label is written Tape Mark Indicates the logical end of volume Two consecutive tape marks ar
465. the file name string and the default name string e The file organization e The record format e Information about disk storage space Creating and Populating Files 4 1 Creating and Populating Files 4 1 File Creation Characteristics The FAB lets you use both the creation time characteristics and the run time characteristics of RMS You must define one FAB for each file your program opens or creates For more information about the FAB see the OpenVMS Record Management Services Reference Manual 4 1 1 2 Extended Attribute Blocks Extended attribute blocks XABs are optional control blocks that contain supplementary file attribute information The following is a partial list of XABs that can be used to provide supporting file information e Initial size and extent information XABALL e File protection XABPRO e Key definition XABKEY e Date and time information XABDAT Like FABs XABs allow you to use both the creation time characteristics and the run time characteristics of RMS With XABs you can define various file attributes beyond those specified in the associated FABs For more information about the extended attribute blocks see the OpenVMS Record Management Services Reference Manual 4 1 2 Using File Definition Language FDL provides a way to create data files using special text files called FDL files FDL files are written in a file definition language which permits you to specify appropriate attributes and values
466. ther a file section from the header and trailer labels or one file from another When written after a set of header labels a single tape mark signals the beginning of a file section When written before a set of trailer labels a single tape mark indicates the end of a file section When written after a trailer label set a single tape mark separates one file from another Double tape marks indicate that either an empty file section exists or the logical end of volume has been reached OpenVMS systems create an empty file when a volume is initialized Labels Labels identify describe and control access to volumes and their files The ANSI magnetic tape format supports volume header and trailer labels The volume labels are the first labels written on a volume They identify the volume and the volume owner and specify access protection Header and trailer labels are sets of labels that identify describe and delimit files Header labels precede files trailer labels follow files Table 1 6 lists the labels supported by OpenVMS operating systems All other ANSI magnetic tape labels are ignored on input Although each type of label uses a different format to organize its contents all labels conforming to Version 3 of the ANSI magnetic tape standard must consist of ASCII a characters Some labels contain reserved fields designed for future system use or future ANSI magnetic tape standardization Reserved fields also must consist of ASCI
467. thout any application change e You should use any of the methods only as appropriate for the application In particular you should check for any dependency in an existing application on the alternate success status RMS OK RLK or RMS OK RRL File Sharing and Buffering 7 11 File Sharing and Buffering 7 2 Record Locking Table 7 5 Methods Available for Specifying No Query Record Locking To Use This Method Disable query record locking at the Enter the following DCL command to request the RMS use no process or system level query record locking for any read operation with both RAB V_ NLK and RAB V_RRL options set in the RAB L_ROP field SET RMS DEFAULT QUERY LOCKING DISABLE SYSTEM Keys on RAB V_NLK and RAB V RRL options in existing applications Enable no query record locking on a Set the RAB V_NQL option in the RAB W ROP 2 field per record read operation The RAB V NQL option takes precedence over all other record locking options Use only if the current read GET or FIND operation is not followed by an UPDATE or DELETE call Enable no query record locking at the file Set the FAB V_NQL option in the FAB B_SHR field to request level that RMS use no query locking for the entire period the file is open for any read record operation with both RAB V_NLK and RAB V RRL options set in the RAB L_ROP field This option can be used with any combination of the other available FAB B_SHR sharing options Keys on RAB V_NL
468. tial allocation 3 4 internal structure 10 1 locking in an OpenVMS Cluster 3 33 magnetic tape 1 19 organization 1 2 2 13 2 14 selecting 2 1 reserved list of 1 8 specifying one or many 5 29 volume configurations 1 24 Files truncating 3 9 Files 11 CD on dual format CDs 1 4 Files 11 disk structures 1 8 file headers 1 9 home block 1 8 levels compared 1 11 reserved files 1 8 Files 11 On Disk Structure comparison of ODS Levels 1 2 and 5 1 4 definition 1 3 File section number field 1 30 File sequence number field 1 30 File set identifier field 1 30 File sharing 3 12 9 6 compatibility with subsequent record access 7 5 to 7 6 defaults 7 5 interlocked interprocess 7 2 7 5 to 7 6 multistreaming 7 2 7 4 no access function 7 4 options 7 4 user interlocked interprocess 7 2 7 4 7 6 7 7 File specification parsing 6 4 to 6 11 conventions used by RMS 6 4 to 6 11 for input file 6 9 for output file 6 10 for related file 6 8 to 6 9 logical name 6 5 to 6 6 search list 6 7 to 6 8 File specifications 1 28 See also Default file specifications applicable services and routines 5 21 to 5 27 components 5 1 5 2 default 5 17 6 1 to 6 4 9 6 directory 6 11 to 6 18 format 5 1 to 5 14 6 5 6 6 for remote file access 5 3 5 21 input 6 9 length limits 5 12 output 6 10 preprocessing 5 21 primary 6 1 to 6 4 9 6 program supplied 6 1 to
469. tially in sorted order using a key embedded in the record The record format refers to the way all records in a file appear physically on the recording surface of the storage medium and is defined in terms of record length Table 1 2 describes the four record formats supported by RMS Table 1 2 Record Formats Record Format Description Fixed length All records are the same length Variable length Records vary in length Each record is prefixed with a count byte that contains the number of bytes in the record The count byte may be either MSB or LSB formatted Variable record length with Records do not have to be the same length but each fixed length control includes a fixed length control field that precedes the variable length data portion continued on next page Introduction 1 1 File Concepts Table 1 2 Cont Record Formats Record Format Description Stream Records are delimited by special characters or character sequences called terminators Records with stream format are interpreted as a continuous sequence or stream of bytes The carriage return and the line feed characters are commonly used as terminators When you design a file you specify the file storage medium and the file and record characteristics directly through your application program or indirectly using an appropriate utility Chapter 2 outlines RMS file organization record access modes and record characteristics in detail Afte
470. tics e Initial load record count e Additional record count The selected range is displayed along the graph s vertical axis The variable on the graph s horizontal axis is bucket size The numbers in the field portion of the graph show the number of levels at each bucket size for each of the other values Figure 4 2 is a Surface Plot graph that shows a range of values for initial fill factors ranging from 100 to 40 Figure 4 2 Surface Plot Graph Initial Load Fill Percent 100 90 80 70 60 50 40 4 3 2 2 2 2 2 2 2 2 2 21222 2 2 2 2 2 2 222 2 22 IL 1 4 1 1 43322222222222Y22222222222222222111 43 3 2222222222 2222222222222222211 43 3 2222222222 2222222222222222222 43 3 2222222222 2222222222222222222 43 3 2222222222 2222222222222222222 433 3 222222222 2222222222222222222 433 3 222222222 2222222222222222222 433 3 222222222 2222222222222222222 4333 3 222222222 222222222222222222 4433 3 222222222 222222222222222222 54333 3 222222222 22222222222222222 543333 3 22222222 22222222222222222 t t te ee Ht HH Ht HHH tH Ht Ft 1 5 10 15 20 25 30 32 Bucket Size Number of Blocks ZK 0949 GE The area on the graph within the slash marks represents combinations that RMS finds acceptable In Figure 4 2 a fill factor of 7096 and a bucket size of 10 blocks is the optimum combination A fill factor of 70 and a bucket size of 15 blocks is a relatively poor combination because it falls outside of the slash boundar
471. tiguous request returns an error if contiguous disk blocks cannot be found to satisfy the request The second called a contiguous best try request attempts to find contiguous disk blocks for the request If it does not find sufficient contiguous space it extends the file and does not return an error The contiguity options can be input to an EXTEND service in the FAB FAB V CBT FAB V_CTG or in the Allocation XAB XAB V_CBT XAB V CTG The Allocation XAB settings override any FAB settings When RMS automatically extends a file the application can only indirectly control contiguity by setting the FAB or XABALL contiguity bits on input to the CREATE service Once set on file creation these options are available for subsequent extends done automatically by RMS 3 8 Performance Considerations Performance Considerations 3 2 Tuning Note that setting the FAB V_CTG bit could cause an extend to fail on a sufficiently fragmented disk Note too that the FAB V CBT option is disabled after several failures to allocate contiguous disk space to avoid the expensive overhead of contiguous best try processing on a badly fragmented disk 3 2 1 4 Truncating a File Only RMS sequential disk files that have been opened for write access FAB V_ PUT FAB V UPD FAB V DEL or FAB V_TRN can be truncated This applies to unshared and shared sequential files Two types of truncation can occur on RMS sequential files RMS truncation and Ancillary Control
472. tiguous space allocation 3 13 defining file characteristics 4 32 using RMS 4 31 using the Edit FDL utility 4 2 Ctrl Z key sequence 4 3 Current context current record position 8 16 to 8 17 listed for OpenVMS record management services 8 15 next record position 8 17 Current record position 8 3 8 4 Cylinders 1 12 3 10 boundary 3 16 options for 4 35 D DATA BUCKET structure 10 15 10 18 Data compression 3 19 Data files creating 4 15 creating with FDL CREATE routine 4 13 4 16 reorganizing 10 27 Data reliability 9 11 Data storage file organization and 3 2 Data types 3 19 DATA AREA attribute 3 25 Date information option 4 32 DATE primary 4 32 DCL commands for Analyze RMS File utility 10 11 for the Edit FDL utility 4 3 DCL interface for enabling RMS statistics gathering 3 29 Deadlock detection record locking 7 17 Default extension option 4 35 Default extension quantity CREATE fixing of value 3 7 determining factors 3 7 file 3 5 for multiple area file 3 6 how determined for indexed files 3 6 process 3 5 set permanently using FAB and XAB 3 6 set permanently with FDL editor 3 6 setting with DCL 3 7 setting with VOLUME EXTENSION n 3 8 specified by RMS 3 5 system 3 5 volume 3 5 Default file specifications 6 1 to 6 4 9 6 Deferred write processing 9 8 DEFERRED WRITE attribute 7 21 7 22 DEFINE command 6 14 TRANSLATION ATTRIBUTES qualifier 5 20 D
473. til the file is found or the search list is exhausted Like other logical names a search list is usually defined using the ASSIGN or DEFINE commands however in a search list logical name the multiple file specifications equivalence names must be separated by commas Any of the equivalence names in the search list may be specified individually as being terminal or being concealed Section 6 2 describes the use of search lists and wildcard characters for multiple file processing and parsing For general information about using logical names refer to the OpenVMS User s Manual 5 20 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 8 Introduction to File Parsing 5 8 Introduction to File Parsing RMS allows an application program to specify defaults for the device and directory components of a file specification as well as other components of a file specification The method RMS uses to apply defaults and translate any logical names present is called file parsing In effect RMS merges the various default strings after translating any logical names to generate the file specification used to locate the file One of the functions of file parsing is to determine when a logical name is present and whether the file specification describes a file on the local node If a node name is not present in the file specification the file is located on the local system RMS translates any logical names applies defaults to any miss
474. tion RMS does not generate the resultant string until the program invokes a related service such as SYS SEARCH which uses the expanded string from the Parse service as input When you use a search list the expanded string contains the first location to be searched RMS stores internally the information that specifies the remaining search list equivalence strings Note that the equivalence string from a PARSE is not guaranteed to point to an actual file As different file locations are examined RMS updates the expanded string to reflect the current location and the resultant string contains the actual file specification of the file With the Create Display Erase Open and Search services defaults are applied to the expanded string to select the actual file used The resultant string can be used by the program to indicate which file was located When the file is located the version number found or created is appended to the resultant file specification string not the expanded file specification string When a search list is used the resultant string contains the file specification where the file was actually found 6 4 Advanced Use of File Specifications Advanced Use of File Specifications 6 2 Understanding RMS Parsing The following sections describe the steps that RMS uses to create a complete file specification 6 2 1 Checking for Open by Name Block If the open by name block option is specified FAB V NAM RMS examines the
475. tive files also begins with the FILE HEADER and FILE ATTRIBUTES structures From the FILE ATTRIBUTES structure the next structure down is the PROLOG The first structure down from the PROLOG is the FIRST DATA BUCKET The data bucket structures can be examined with the REST command or one at a time with the NEXT command The only information at the data bucket level is the number of the data bucket s virtual block The next structure down is the FIRST RECORD CELL IN FIRST BUCKET You can examine the records in each cell by specifying either the REST command or a series of NEXT commands Example 10 4 shows an interactive examination of a relative file Maintaining Files 10 15 Maintaining Files 10 1 Viewing File Characteristics Example 10 4 Examining a Relative File FILE HEADER File Spec DISKSNEWWORK RMS32 REL DAT 1 File ID 9573 7 2 Owner UIC 181 065 Protection System RWED Owner RWED Group RE World Creation Date 22 MAY 1993 10 42 04 95 Revision Date 22 MAY 1993 10 42 05 81 Number 1 Expiration Date none specified Backup Date none posted Contiguity Options contiguous best try Performance Options none Reliability Options none ANALYZE DOWN RMS FILE ATTRIBUTES File Organization relative Record Format variable Record Attributes carriage return Maximum Record Size 75 Blocks Allocated 9 Default Extend Size 0 Bucket Size 3 File Monitoring disabled Global Buffer Count 0 ANALYZE DOW
476. to retrieve records in the logical order represented by any index To retrieve records sequentially from an indexed file your program must first specify a key of reference for example primary key first alternate key second alternate key and so on For successive retrievals RMS uses the appropriate index to retrieve records based on how the records are ordered in the index If RMS accesses the index in ascending sort order it returns the record with a key value equal to or higher than the key value in the previously accessed record Conversely if RMS accesses records in descending order it accesses the next record having a key value equal to or lower than the key value in the previously accessed record In contrast to a request to retrieve data sequentially from an indexed file a request to store data sequentially in an indexed file does not require a key of reference Rather RMS uses the definition of the primary key to place the record in the primary index and where applicable uses the definition of the appropriate alternate key to place a record pointer in the alternate index When a program issues a series of requests to sequentially store data RMS verifies that the key value in each successive record is ordered correctly Choosing a File Organization 2 5 Choosing a File Organization 2 1 Record Concepts 2 1 1 2 Random Access by Key Value or Relative Record Number RMS supports random access for all relative files all inde
477. tors as defined by the relevant recording standard Logical sectors are numbered in ascending order The value 0 is assigned to the logical sector with the lowest physical address containing recorded data Each logical sector includes a data field made up of at least 2048 bytes but in all cases the number must be a power of 2 ISO 9660 formatted CD ROM volumes include a system area and a data area The reserved system area includes logical sectors 0 through 15 The data area includes the remaining logical sectors and is called volume space Volume space is organized into logical blocks that are numbered in consecutively ascending logical block number order Logical blocks are made up of at least 512 bytes but in all cases the number of bytes must be a power of 2 However no logical block can be larger than a logical sector SO 10149 Data Interchange on read only 120mm Optical Discs CD ROM the Yellow Book 1 14 Introduction Introduction 1 2 Disk Concepts The data area may include one or more Volume Descriptors File Descriptors Directory Descriptors and Path Tables These entities collectively describe the volume and file structure of an ISO 9660 formatted CD ROM The Ancillary Control Process ACP that manages I O access to the CD ROM views the volume and file structure as an integral part of the base OpenVMS file system 1 2 5 3 Files 11 C D ACPs The Files 11 C D implementations allow OpenVMS systems to confor
478. tream that is modifying the record Contending record streams can read the record using the no locking option or the read regardless option see Section 7 2 3 3 When a contending record stream reads a write locked record using the no locking option the accessing service returns a success status Typically an application program uses the write locking option when it wants the record to remain in a consistent state while the application program is modifying the record File Sharing and Buffering 7 9 File Sharing and Buffering 7 2 Record Locking 7 2 2 3 Read Locking The read locking option permits other record streams to access the record for reading but denies access to any record stream that attempts to access the record for making modifications No record stream is allowed to access a read locked record for making modifications to the record until all record streams that have a read lock release the record Any record stream that attempts to access a read locked record using either the exclusive locking option or the write locking option are denied access The requesting service returns a completion status record to the application program indicating that the record was locked RMS RLK and the requesting record stream was denied access Contending record streams can read the record using the read locking option the no locking option or the read regardless option see Section 7 2 3 3 When a contending record stream accesses a
479. tributes 7 3 Access categories 4 26 Access control lists See ACLs Accessibility field 1 27 1 31 Accessing files on ODS 5 disks VAX systems 5 14 Access modes See also Record access mode ACLs access control lists as protection basis 4 26 compared with UIC protection 1 35 ACP truncation determining factors 3 9 error 3 9 using the FAB V_TEF bit 3 9 Active Streams field interpretations of zero reading 3 29 ADD command 10 25 AGAIN command 10 11 Allocation 3 24 4 34 A 1 ALLOCATION attribute 3 25 4 35 Allocation quantity option 4 35 Alternate indexes 3 22 Alternate keys 3 18 3 19 Alternate record structure 10 21 Analysis section 4 4 10 1 10 26 ANALYSIS OF AREA section 10 1 10 22 ANALYSIS OF KEY section 10 1 10 22 Analyze RMS File utility ANALYZE RMS FILE 1 37 10 1 10 26 commands 10 11 default file type 10 5 examining prologs 3 18 file optimizing 4 4 with FDL files 4 2 Index ANL file type 10 5 ANSI magnetic tape file names 1 28 standard 1 19 volumes 1 19 1 22 format 1 20 ANY CYLINDER option 4 35 Application design 2 1 shared access consideration 3 3 space consideration 3 2 speed consideration 3 1 Area default extension quantity 3 6 AREA DESCRIPTOR structure 10 17 Area options 4 35 Areas 3 24 defining multiple in an FDL file 3 25 multiple on a volume set 3 24 ASCII character set 1 20 ASSIGN command TRANSLATION ATTRI
480. trol block field RAB B_MBF or the XAB MULTIBUFFER COUNT XABITM The number of buffers each application needs depends on the type of record access your application performs The minimum number of buffers for indexed files is two If the application performs sequential access on your database two buffers are sufficient More than two buffers for sequential access could actually degrade performance During a sequential access a given bucket is accessed as many times in a row as there are records in the bucket After RMS has read the records in that bucket the bucket is not referenced again Therefore it is unnecessary to cache extra buckets when accessing records sequentially When you access indexed files randomly RMS reads the index portion of the file to locate the record you want to process RMS tries to keep the higher level buckets of the index in memory the buffers for the actual data buckets and the lower level index buckets tend to be reused first when other buckets need to be cached Therefore you should use as many buffers as your process working set can support so you can cache as many buckets as possible When you access records sequentially even after you have located the first record randomly you should use a large bucket size A small multibuffer count such as the default of two buffers is sufficient If you process your data file with a combination of the above access modes you should compromise on the recommended bucket
481. tructure called a volume set Because Introduction 1 2 Disk Concepts a volume set consists of two or more related volumes the system treats it as a single volume Note The terms disk and volume are used interchangeably in this document The smallest addressable logical structure on a Files 11 ODS disk is a block comprising 512 8 bit bytes During input output operations one or more blocks may be transferred as a single unit between a Files 11 ODS disk and memory RMS allocates disk space for new files or extended files using multiblock units called c usters The system manager specifies the number of blocks in a cluster as part of volume initialization Clusters may or may not be contiguous share a common boundary on a disk Cluster sizes may range from 1 to 65 535 blocks Generally a system manager assigns a small cluster size to a disk with a relatively small number of blocks Relatively larger disks are assigned a larger cluster size to minimize the overhead for disk space allocation An extent is one or more adjacent clusters allocated to a file or to a portion of a file If enough contiguous disk space is available the entire file is allocated as a single extent Conversely if there is not enough contiguous disk space the file is allocated using several extents which may be scattered physically on the disk Figure 1 2 shows how a single file File A may be stored as a single extent or as multiple extents Fig
482. ttribute 7 16 MULTIBLOCK COUNT attribute 3 14 7 20 9 9 MULTIBUFFER COUNT attribute 3 14 3 16 3 277 7 19 to 7 21 9 9 NOLOCK attribute 7 13 9 15 NONEXISTENT RECORD attribute 7 16 8 8 9 16 READ AHEAD attribute 9 9 9 16 READ REGARDLESS attribute 7 14 9 17 TIMEOUT PERIOD attribute 7 14 9 17 9 19 TRUNCATE ON PUT attribute 9 10 9 20 UPDATE IF attribute 8 7 9 11 9 20 WAIT FOR RECORD attribute 7 14 9 18 WRITE BEHIND attribute 9 10 9 20 FDL files creating 4 2 creating data files 4 15 creating with FDL GENERATE routine 4 13 designing 4 10 examining with ANALYZE RMS FILE 10 1 generating from a data file 10 22 FDL FILE section ALLOCATION attribute 3 4 3 25 4 35 BEST TRY CONTIGUOUS attribute 3 4 4 35 BUCKET SIZE attribute 3 16 3 25 4 32 7 20 7 21 CONTIGUOUS attribute 3 4 3 25 4 35 CONTROL FIELD SIZE attribute 4 33 CREATE IF attribute 4 31 DEFAULT NAME attribute 6 3 9 7 DEFERRED WRITE attribute 3 17 3 27 7 21 7 22 9 8 FDL FILE section cont d DIRECTORY ENTRY attribute 4 32 EXTENSION attribute 4 36 9 7 9 8 GLOBAL BUFFER COUNT attribute 3 13 7 19 7 23 MAXIMIZE VERSION attribute 4 31 MAX RECORD NUMBER attribute 4 33 MT BLOCK SIZE attribute 4 32 MT CLOSE REWIND attribute 9 14 MT CURRENT POSITION attribute 9 14 MT NOT EOF attribute 9 13 MT OPEN REWTIND attribute 9 14 MT
483. ttribute with an AREA by assigning the appropriate area number to the LEVEL1 INDEX AREA attribute You also assign the appropriate area number to the INDEX AREA attribute for the other index levels in the primary index structure For each alternate index structure you use the same attributes DATA AREA LEVELI1 INDEX AREA INDEX AREA in another KEY primary attribute In KEY sections that define alternate keys the DATA AREA is where RMS puts the SIDRs 3 5 2 Optimizing File Performance This section discusses adjustments in file design that can improve a file s performance 3 5 2 1 Bucket Size For indexed files the bucket size controls the number of levels in the index structure which has the greatest impact on performance for most applications You can specify the bucket size with the FDL attribute FILE BUCKET_SIZE or the control block fields FAB B_BKS and XAB B_BKZ When you sequentially access files large buckets are generally beneficial For keyed access to index files set the bucket size so that the number of index levels does not exceed four In general the smaller the bucket size the deeper the tree structure If you find that a small increase in bucket size eliminates one level use a larger bucket size At some point however the benefit of having fewer levels is offset by the cost of scanning through the larger buckets As a rule you should never increase bucket size unless the increase reduces the number of levels For e
484. ttributes in some languages but they must be explicitly specified in others You implement read ahead and write behind processing by using two buffers The processing program uses one buffer and the I O subsystem uses the other In read ahead processing the program reads data from one buffer as the second buffer inputs data from the disk In write behind processing one buffer accepts output data from the program while the second buffer outputs program data to a disk The next section provides additional information about read ahead and write behind processing 3 3 Tuning a Sequential File Sequential files consist of a file header and a series of data records Records are stored in the order in which they are written to the file The following sections provide guidelines for improving the performance of sequential file processing using various tuning options 3 3 1 Block Span Option You should always specify that records in a sequential file are permitted to span blocks that is to cross block boundaries In this way RMS can pack the records efficiently and avoid wasted space at the end of a block Note that you cannot turn off this option for STREAM formatted files By default the FDL editor activates block spanning for files organized sequentially by setting the RECORD secondary attribute BLOCK SPAN to YES If you are using a low level language you activate the block span option directly in the FAB by resetting the FAB V_BLK
485. uage FDL 0 0 0 0 cee eee eee 1 6 2 RMS Data Structures 1 2 llle 1 6 3 Record Management Services 1 0 0 cece cece eee ee 1 7 RMS Utilities ice xr ao he dias Ba BERS Ra Ria e e ea A nue n 1 7 1 The Analyze RMS File Utility 20 00 00 eee eee 1 7 2 The Convert Utility lt 3 c c 2 e0d awe bas CE baw e ER we EEG RR 1 7 3 The Convert Reclaim Utility 2 0 0 0 00 ccc eee 1 7 4 The Create FDL Utility lt i44 aga RE E EEPRRGx ELE ES 1 7 5 The EdW FDIL Utility 5 od m ee RR mnm I eR de 4 1 8 Process and System Resources for File Applications 1 8 1 Memory Requirements llle eee eee 1 8 2 Process LXmulbs 22522 o9 durs rues deor dt dale ee a beaded bess 2 Choosing a File Organization 2 1 Record Concepts ada tess ekas rd RE eh EENS EERS de dod a 2 1 1 Record Access Modes llle 2 1 1 1 Sequential Access ia deed gaa eR EA Rote oS ede ecu AC 2 1 1 2 Random Access by Key Value or Relative Record Number 2 1 1 3 Random Access by Record File Address 00005 2 1 2 Record Formats 22532544424 06040054050 20004 Ur s P SUR Nee a oon 2 1 2 1 Fixed Length Record Format llle 2 1 2 2 Variable Length Record Format 000 eee cece 2 1 2 3 Variable Length with Fixed Length Control Field VFC Record E ormal 52es9as exe eee fue uer poder ides ego Po ee Ra qun 2 1 2 4 Stream Record Format lees 2 2 File Organization Concept
486. ucture pointer to the next structure on the current level The structure is displayed Pressing the Return key is equivalent to a NEXT command REST Moves the structure pointer along the rest of the structures on the current level and each is displayed in turn TOP Moves the structure pointer up to the file header The file header is displayed UP Moves the structure pointer up to the next level The structure at that level is displayed Maintaining Files 10 11 Maintaining Files 10 1 Viewing File Characteristics 10 1 4 Examining a Sequential File Figure 10 1 shows the tree structure of a sequential file Figure 10 1 Tree Structure for Sequential Files File Header File Attributes The FILE HEADER structure is always the first structure displayed From the FILE HEADER structure the DOWN command moves the current position to the FILE ATTRIBUTES structure The DOWN command from the FILE ATTRIBUTES structure moves the current position to the first record in the file From the first record the REST command will move the current position through the records in the file displaying each one in turn A series of NEXT commands will also accomplish this same operation eee Last Record ZK 0327 GE Figure 10 2 shows the layout and contents of the records in a sequential file SEQ DAT Example 10 3 is an interactive examination of SEQ DAT showing the contents of three records in the file Figure 10 2 Record Layou
487. uence For information about NCS see the OpenVMS National Character Set Utility Manual When the application program creates the data file it uses the pointer to copy the collating sequence from local memory into the data file s prolog space A collating sequence is typically 1 block long The application program may specify a collated key from either the RMS interface or the FDL interface From the RMS interface the application program identifies the collating sequence using an appropriate string descriptor and includes a symbolic reference to the location of the pointer As with all other keys the application program may specify either ascending or descending sort order From the RMS interface you specify the key data type COL for an ascending sort order or the key data type DCOL for descending sort order From FDL you specify a collated key by selecting one of the collated key data types collated for ascending sort order decollated for descending sort order from the INDEXED file script FDL responds by prompting for the name of the collating sequence If you enter an invalid collating sequence any attempt to use the FDL file for creating a data file will be unsuccessful and NCS generates the following error message 1 This manual has been archived but is available on the OpenVMS Documentation CD ROM A printed book can be ordered by calling 800 282 6672 2 24 Choosing a File Organization Choosing a File Organization 2
488. until end of file or other error condition C 10 READ 1 100 END 20 ERR 20 NCHAR BUFFER NCHAR WRITE 2 200 BUFFER NCHAR GOTO 10 C C Close the input and output files C 20 CLOSE UNIT 2 CLOSE UNIT 1 END You can substitute the system logical name defined on a remote system as one or more of the components in the remote file specification as follows e Device alone e Both device and directory e Complete file specification if it includes node A logical name that includes the device directory and filename components but does not include the node as illustrated in the following example is not supported in a remote file specification SDEFINE SYSTEM myfile work2 userl a a SDIRECTORY alphal userl password myfile SDIRECT W NOFILES no files found SDIRECTORY alphal userl password myfile DIRECT E OPENIN error opening ALPHA1 USER1 password MYFILE as input RMS F FNM error in file name Note that a foreign file specification would work SDIRECTORY alphal userl password myfile Directory 0 userl password WORK2 USER1 A A 2 Locating and Naming Files on Disks 5 19 Locating and Naming Files on Disks 5 7 Types of Logical Names 5 7 Types of Logical Names When a logical name is defined you can assign it various translation attributes including the concealed attribute and the terminal attribute By default a logical name is neither concealed nor terminal To specify a logical name as either
489. up 10 28 minimizing 3 26 BUCKET SIZE attribute 4 32 7 20 7 21 Buffer areas requirement for Get service 8 2 Buffer caches 7 4 7 20 for storing index levels 7 21 types 7 22 using with multistreaming 7 4 Buffered I O byte count quota 9 8 Buffering techniques 7 17 to 7 25 Buffer offset length field 1 33 Buffers See also Global buffers IO 3 2 7 18 key 9 13 9 15 9 18 local 3 13 3 28 7 22 multiple 3 11 number of 3 14 3 27 record header 9 17 9 19 9 20 selecting for optimum performance 7 18 to 7 20 space allocation 7 18 user 9 17 9 18 Index 2 BUFFER COUNT qualifier 7 20 7 21 7 22 Bytes 1 1 C C sample search key option program 8 10 Caches buffer 7 4 for file sharing 9 6 global 7 23 specifying as read only 7 24 with multiple buffers 9 9 memory 3 14 3 16 3 18 3 27 for file sharing 3 17 for random processing 3 17 for storing index 3 26 relative to bucket size 3 26 process local 3 12 Calling FDL PARSE and FDL RELEASE from a Pascal program 4 13 Carriage return terminator for stream records 2 13 CARRIAGE CONTROL attribute 4 34 CD ROM compact disc read only memory 1 5 1 6 concepts 1 14 formats 1 14 using Digital System Identifiers 1 15 volume structure 1 14 Cells fixed length 3 15 record structure and 10 15 CHECK qualifier 10 1 Check report 10 1 10 5 Clusters disk allocation 1 7 COBOL calling CONVERT routines f
490. ure 1 2 Single and Multiple File Extents Single Extent for File A e Multiple Extent for File A _ Pr ZK 0738 GE Introduction 1 7 Introduction 1 2 Disk Concepts With RMS you can exercise varying degrees of control over file space allocation At one extreme you can specify the number of blocks to be allocated and their precise location on the volume At the other extreme you can allow RMS to handle all disk space allocation automatically As a compromise you might specify the size of the initial space allocation and have RMS determine the amount of space allocated each time the file is extended You can also specify that unused space at the end of the file is to be deallocated from the file making that space available to other files on the volume When you need a large amount of file storage space you can combine several Files 11 ODS volumes into a volume set with file extents located on different volumes in the set You need not specify a particular volume in the set to locate or create a file but you may improve performance if you explicitly specify a volume for a particular allocation request 1 2 2 Files 11 Control Files Ten files control the structure of a Files 11 On Disk Structure Level 2 volume Only five of these files are used for a Files 11 On Disk Structure Level 1 volume Table 1 5 identifies all nine files which are referred to as reserved files and 1 2 2 1 1 8 Introduction indi
491. used by media failure or scheduled preventive maintenance Similarly when you use a logical name and the current copy of a file is not available an alternate file can be used To locate several files in a defined search order you can use a search list which is a form of logical name Alternatively you can use wildcard characters to locate several files using one file specification however wildcard characters do not allow you to specify a search order Using a logical name to represent a complex file specification or a file specification component reduces keystrokes to save time and reduces the chance of error For example you could define a logical node name that translates to an actual node name and access control string for use when locating remote files To keep the password a secret when you use this technique the logical name should be defined interactively rather than in a command procedure RMS attempts to treat the file name component as a logical name if the file name is the only component in the file specification Refer to the OpenVMS User s Manual for additional information on defining logical names No logical name translation is done on any logical name that contains a compound character containing the RMS escape character 5 4 File Specification and Component Length Limits The following section describes a file specification on ODS 2 and ODS 5 disks 5 4 1 VAX Systems and ODS 2 Disks on Alpha Systems The maximum
492. variable length records the Update service can modify the record length up to the maximum size specified when the file was created When you insert a record into a relative file the record is placed in a fixed cell within the file A cell within a relative file can contain a record can be vacant never have contained a record or can contain a deleted record The following sections discuss the sequential and random access modes for relative files 8 4 2 1 Sequential Access For relative files the sequential access mode can be used to retrieve successive records in ascending record number Vacant cells and cells that contain deleted records are skipped over automatically 8 4 2 2 Random Access You can directly read a record within a relative file by specifying the appropriate relative record number If you attempt to read from a nonexistent cell that is a vacant cell or a cell containing a deleted record RMS returns an error message To position the record stream at a particular cell regardless of whether or not it contains a record use the nonexistent record option FDL attribute CONNECT NONEXISTENT RECORD or set the RAB V_NXR bit in the RAB L_ROP field You can use the forward search key options equal or next key and next key to directly access records in relative files but the reverse search key options are not supported for relative files The equal or next key option FDL attribute CONNECT KEY GREATER EQUAL directs R
493. ve performance If you choose to select the bucket size you should also consider how your application accesses the file For random access you may want to choose a small bucket size for sequential access a large bucket size and for mixed access a medium bucket size One way to improve performance for a relative file is to align the file on a cylinder boundary and specify the size of one disk track as the bucket size However this requires that you can perform an exact alignment on the file If you use the FDL editor to establish the bucket size this is recommended the editor fixes the size at the optimum value based on your script inputs If you intend to access the file randomly EDIT FDL sets the bucket size equal to four records because it assumes that four records are a reasonable amount of data for a random access If you intend to access records sequentially EDIT FDL sets the bucket size equal to 16 records because it assumes that 16 records is a reasonable amount of data for one sequential access If you find that your application needs more data per access then use the EDIT FDL command MODIFY to change the assigned values 3 4 2 Number of Buffers The multibuffer count is a run time option that you can set with the DCL command SET RMS DEFAULT RELATIVE BUFFER COUNT z the FDL attribute CONNECT MULTIBUFFER COUNT the RMS control block field RAB B MBF or the XAB MULTIBUFFER COUNT XABITM The type of record access determin
494. vice before invoking the Create service 5 22 Locating and Naming Files on Disks Locating and Naming Files on Disks 5 9 Using One File Specification to Locate Many Files The create if option tries to open any file found in the search list If the file is not found in the search list RMS creates it using the first file specification in the search list If these options are specified and a wildcard character is present when the Create service is invoked the file specification is invalid if a search list is present the file is created using the first file specification from the search list You can either call these services directly from a VAX MACRO procedure as part of a USEROPEN or USER ACTION routine in a high level language or you may execute the calls from high level language subroutines or functions that call RMS The Parse and Search services require that a name block be present Unless your language supports a means of setting values in a name block and other control blocks and invoking RMS you should use a VAX MACRO procedure FDL does not support the use of a name block In addition to a name block you usually need a file access block FAB and a record access block RAB To perform file services a FAB and if needed extended attribute blocks XABs must be present to perform record services a RAB must be present The following program shows how to use the LIB FIND FILE routine to locate the desired file which the in
495. vices work together to provide a fully qualified file specification that the Search service uses to locate the file Your program can process a single file without using the Search service if neither the file specification nor the search list contain wildcard characters If any of the file specifications in a search list contain wildcard characters the Search service must be invoked before processing the file to prevent an invalid wildcard completion status error If a wildcard character is present in the second or subsequent file specifications in a search list RMS does not set the wildcard bit in the file name status bits field If the Parse and Search services precede an Open service an open by name block operation should be performed by specifying the address of the name block in the name block address FAB L_NAM or FAB L_NAML field and setting the file processing options FAB L_FOP open by name block FAB V_NAM bit option Wildcard characters cannot be present in the file specification when the Create service is invoked Sometimes the Parse service and the Search service precede a Create service When the create if option bit FAB V_CIF or the supersede option bit FAB V_ SUP is set in the file processing options FAB L_FOP field the program may invoke the Parse service to check for wildcard characters or search lists in the file specification If a search list or wildcard characters are found the program must invoke the Search ser
496. when you are locating or reading records When you specify descending sort order RMS returns the record with the next lower key value e FDL CONNECT KEY_GREATER_THAN e RMS RAB L_ROP RAB V_NXT Key of reference Specifies which key is used for current record stream for indexed files with multiple keys e FDL CONNECT KEY OF REFERENCE e RMS RAB B_KRF Run Time Options 9 15 Run Time Options 9 3 Summary of Record Operation Options Option Description Key size Limit key Locate mode Lock nonexistent record Lock for read Lock for write Manual locking Read ahead 9 16 Run Time Options Specifies that all or part of the key be used when you are using a string key to locate or read records e FDL None e RMS RAB B KSZ Directs RMS when locating or reading records sequentially to return an alternate success status if the record key exceeds the specified key e FDL CONNECT KEY_LIMIT e RMS RAB L_ROP RAB V_LIM Specifies the locate mode instead of the move mode Applies to the Get service only e FDL CONNECT LOCATE_MODE e RMS RAB L ROP RAB V_LOC Indicates that RMS is to lock the record position at the location of the following record operation regardless of whether a record exists at that location Applies only to relative files e FDL CONNECT NONEXISTENT_RECORD e RMS RAB L ROP RAB V_NXR Locks record for reading and allows other readers but no writers e FDL CONNECT LOCK_ON_REA
497. wo sections describe RMS record access modes and record formats respectively 2 1 1 Record Access Modes RMS provides two record access modes sequential access and random access Random access can be further catalogued as one of the three following modes e Random access by key value e Random access by relative record number e Random access by record file address RFA Although you cannot change its file organization after you create a file you can change the record access mode each time you access a record in the file For example a relative file can be processed in sequential access mode one time and in a random access mode the next time Table 2 1 lists the combinations of record access modes and file organizations supported by RMS Table 2 1 Supported Record Access Modes and File Organizations File Organization Access Mode Sequential Relative Indexed Sequential Yes Yes Yes Random by relative Yes Yes No record number Random by key No No Yes value Random by record Yes Yes Yes file address 1Permitted with fixed length record format on disk devices only Permitted on disk devices only The following sections describe the record access modes and the capability for switching from one mode to another during program execution 2 2 Choosing a File Organization Choosing a File Organization 2 1 Record Concepts 2 1 1 1 Sequential Access In sequential access mode storage or retrieval begins at a designated po
498. xample you may find that a bucket size of 4 or more yields an index with four levels and a bucket size of 10 or more yields an index with three levels In this case you never want to specify a bucket size of 9 because that does not reduce the number of levels and performance does not improve In fact such a specification could hurt performance because each I O operation takes longer yet the number of accesses remains the same However larger bucket sizes always improve performance if you are accessing the records sequentially by primary key because more records fit in a bucket Performance Considerations 3 25 Performance Considerations 3 5 Tuning an Indexed File Conversely with smaller buckets you have to search fewer keys So if you can cache your whole structure except for level 0 you can save a lot of time Also performance in this case is comparable to flat file design although add operations may take a little longer You can decrease the depth of your index structure in two ways First you can increase the number of records per bucket by increasing the bucket size increasing the fill factor using compression or decreasing the size of keys and records Note You cannot use key compression or index compression with the collated key data type However changing the bucket size also has disadvantages Larger buckets use more buffer space in memory And the number of records per bucket determines bucket search time
499. xample 4 2 Cont Sample FDL File KEY 0 CHANGES no DATA AREA 0 DATA FILL 100 DATA KEY COMPRESSION no DATA RECORD COMPRESSION no DUPLICATES no INDEX AREA 1 INDEX COMPRESSION no INDEX FILL 100 LEVEL INDEX AREA 1 NAME E NUM NULL KEY no PROLOG 3 SEGO LENGTH 8 SEGO POSITION 0 TYPE bin8 KEY 1 CHANGES yes DATA AREA 2 DATA FILL 100 DATA KEY COMPRESSION yes DUPLICATES yes INDEX AREA INDEX COMPRESSION yes INDEX FILL 100 LEVEL INDEX AREA 2 NAME T NAME NULL KEY yes NULL VALUE 0 SEGO LENGTH 39 SEGO POSITION 9 TYPE string 4 1 2 2 Designing an FDL File When you want to create an FDL file you invoke the Edit FDL utility with a DCL command in the following form EDIT FDL CREATE fdl filespec The CREATE qualifier specifies that you want to create an FDL file with the name entered in the fdl filespec parameter When the Edit FDL utility displays the main menu select the INVOKE command In response to the INVOKE command the Edit FDL utility prompts you for a script The only appropriate scripts for creating a file are INDEXED RELATIVE and SEQUENTIAL As discussed previously you can enter a script directly by specifying the SCRIPT qualifier on the DCL command line For example enter the following command to create an indexed FDL file EDIT FDL CREATE SCRIPT INDEXED MY FDL FILE When you select the script the Edit FDL utility prompts you for information about the data file Each prompt consists of a short qu
500. xed files and a restricted set of sequential disk files those having fixed length records In random access mode your program not the file organization determines the record processing order For example to randomly access a record in a relative file or a record in a sequential disk file having fixed length records your program must provide the relative record number of the cell containing the record Similarly to randomly access a record from an indexed file your program must provide the appropriate key of reference and key value Random Access to Sequential and Relative Files Unlike sequential access random access follows no specific pattern Your program may make successive requests for storing or retrieving records anywhere within the file In Figure 2 4 the program directs RMS to retrieve the record from the sixth cell in a relative file record C and then requests RMS to retrieve record F which occupies the second cell Figure 2 4 Random Access by Relative Record Number User Program 1 Read Sixth 2 Read Second Cell ZK 0750 GE Compare Figure 2 4 with Figure 2 1 and Figure 2 2 Random Access to Indexed Files To randomly access a record from an indexed file your program must specify both a key value and the index that RMS must search for example primary index first alternate key index and so on When RMS finds a record with a matching key value it passes the record to your program Your program can
501. y using a null key value you minimize the list of duplicates This can improve performance when you insert records because the null key entries do not get processed as index entries Note that when you sequentially access records using null key processing null records are not processed If you use the string data type RMS uses the ASCII null character as the default null key value However you can specify any character as the null value If you use numeric keys RMS uses zero 0 as the null value 3 5 1 4 Records Records in an indexed file can be fixed length records or variable length records Fixed length records begin with a record header Variable length records include a record header followed by a 2 byte count field that contains the number of data bytes in the record Unlike variable length records in relative files each variable length record in an indexed file requires only enough space for the record See Table 2 2 for more information on record overhead Records cannot span bucket boundaries 3 22 Performance Considerations 3 5 1 5 Keys Performance Considerations 3 5 Tuning an Indexed File For Prolog 3 files the maximum record size is 32 224 bytes For Prolog 1 files and Prolog 2 files the maximum length for a fixed length record is 32 234 bytes the maximum length for a variable length record is 32 232 bytes Note that when you specify a record length for a Prolog 3 file that is greater than the maximum record length
502. y Index Structure sss eee ee oksit tr oe eed 3 21 Finding the Record with Key 14 20 0 00 3 22 Line Plot Graphs iau rte oet deem eder ERR vn 4 11 Surface Plot Graph llle eee ees 4 12 Design Mnemonics llle 4 13 Shared Fil AcCess iive a toes tek dae aed PR ed RA Rees 7 1 RMS Buffers and the Application Program 005 7 19 Using Global Buffers for a Shared File 02005 7 23 Using RFA Access to Establish Record Position 8 14 Tree Structure for Sequential Files 0 0 0 0 eee eee 10 12 Record Layout and Content for SEQ DAT 0 0005 10 12 Tree Structure of Relative Files 20 0 eee ee 10 15 Area Descriptor Path 0 0 0 0 eee eee 10 17 Key Descriptor Path oo 042 0caceGee be ee dem ar 9 der UR RE qs 10 19 Structure of Primary Records 00 0 0 ee ees 10 20 Structure of Alternate Records llle 10 21 RMS Tuning Cycle 0 2 eens 10 25 Record Access Methods llle 1 2 Record Formats uuu Rod ee kp Ue ag EO ek n eus 1 2 File Structure Options on OpenVMS Systems 005 1 4 Comparison of ODS 1 ODS 2 and ODS 5 Levels 1 4 Files 11 Control Files llle 1 8 Labels and Components Supported by OpenVMS Systems 1 23 Supported Record Access Modes and File Organizations 2 2 File Organization Characteristics 0
503. y and alternate keys In general as the number of keys increases so does the time it takes to add and delete records from your file If CPU time is a critical resource on your system you should define as few keys as possible Performance Considerations 3 23 Performance Considerations 3 5 Tuning an Indexed File 3 5 1 6 Areas If you are reading records in your file the number of keys has relatively little impact on performance An area is a portion of an indexed file that RMS treats as a separate entity You can divide an indexed file into separate areas where each area has its own bucket size initial allocation extension size and volume positioning just as if each area were a separate file Using multiple areas has distinct advantages However if each area has a different bucket size all buffers are as large as the largest bucket If you use multiple areas the file itself is probably not contiguous however you can make each area within the file contiguous by specifying the FDL attribute AREA CONTIGUOUS To ensure that the area is created without error use the AREA BEST TRY CONTIGUOUS attribute When you separate key and data areas you tend to keep related buckets close together thereby decreasing disk seek time You also minimize the number of disk head movements for a series of operations For example if you have a dedicated multidisk volume set you could place the data level of a file in an area on one disk and the i
504. y editing session Example 9 2 Using the FDL PARSE and FDL RELEASE Routines Me Me Me Me we oM one MY FAB MY RAB FDL FILE REC SIZE 80 LF 10 REC RESULT REC BUFFER HEADING Li T PART FDL This program calls the FDL utility routines FDL PARSE and FDLSRELEASE First FDLSPARSE parses the FDL specification TITLE PSECT LONG LONG ASCID LONG Then the data file named in PART FDL is accessed using the primary key by FDLSPARSE are released by FDLSRELEASE Last the control blocks allocated FDLEXAM DATA WRT NOEXE 0 0 PART FDL Declare FDL file REC SIZE ADDRESS REC BUFFER BLKB ASCID ID PART PSECT REC SIZE SUPPLIER COLOR f F CODE Declare the external routines Li EXTRN ENTRY KEY0 9 22 Run Time Options FDLSPARSE FDLSRELEASE 7 FDLEXAM M lt gt Set up entry mask PUSHAL MY RAB Get set up for call with PUSHAL MY FAB addresses to receive the PUSHAL FDL FILE FAB and RAB allocated by CALLS 3 G FDL PARSE FDLSPARSE BLBS RO KEYO Branch on success BRW ERROR Signal error F MOVL MY FAB R10 Move address of FAB to R10 MOVL MY RAB R9 Move address of RAB to R9 MOVL REC SIZE RABSW USZ R9 MOVAB REC BUFFER RABSL UBF R9 SOPEN FAB R10 Open the file BLBC RO F ERROR SCONNECT RAB R9 Connect to the RAB BLBC RO R ERROR PUSHAQ HEADING Display the heading CALLS 1 G LIBSPUT OUTPUT BLBC RO
505. y existing records or to add new records to the file The file organization is the manner in which data is recorded within a file typically using either fixed length or variable length records The file organization together with the applicable storage medium determines what techniques are used to access data Currently RMS supports two methods of record access sequential access and direct access Direct access includes relative access using the relative position of a record and indexed access using an indexing key within the record See Table 1 1 for more information about record access methods Table 1 1 Record Access Methods Access Method Description Sequential Access Records are stored or retrieved one after another starting at a particular point in the file and continuing in order through the file Relative Record Number Records are stored and retrieved by relative record number Access or by file address Records occupy cells of equal length and each cell is assigned a relative record number which represents the cell s position relative to the beginning of the file Record File Address When a record is accessed directly by its file address the Access distinction is made by its unique location in the file that is its record file address RFA Indexed Access Indexed file records are stored and retrieved by a key in the data record The desired records are usually accessed directly and then retrieved sequen
506. y is more appropriate for large disk files where space is limited Before using the Convert Reclaim utility be sure to back up the file For more information about the Convert Reclaim utility see Chapter 4 of this manual and the OpenVMS Record Management Utilities Reference Manual 1 38 Introduction Introduction 1 7 RMS Utilities 1 7 4 The Create FDL Utility The Create FDL utility CREATE FDL uses the specifications in an existing FDL file to create a new empty data file To invoke this utility use the following DCL command line format CREATE FDL fdl filespec filespec The fdl filespec parameter specifies the source FDL file for creating the data file The filespec parameter gives you the option of assigning a file specification to the data file Figure 1 14 shows how the CREATE FDL utility creates empty data files from the specifications in an FDL file For more information about the CREATE FDL utility see Chapter 4 and the OpenVMS Record Management Utilities Reference Manual Figure 1 14 Using CREATE FDL to Create an Empty Data File CREATE FDL Data File Empty ZK 0945 GE 1 7 5 The Edit FDL Utility The Edit FDL utility EDIT FDL creates and modifies files that contain specifications for RMS data files The specifications are written in the file definition language and the files are called FDL files A completed FDL file is an ordered sequence of file attribute keywords and their associated values B
507. y using an FDL file to specify the characteristics of a data file you can use most of the RMS capabilities without having to access the RMS control blocks directly While you are designing the data model EDIT FDL informs you of syntax errors and the effects of altering file characteristics Using EDIT FDL you can experiment with attributes that are critical to the record processing performance of the file and you can calculate optimum file size For example the depth of an index is an important consideration in designing an indexed file and bucket size is one variable that determines the number of levels EDIT FDL can show the effects of varying the bucket size on the index depth to help you choose the optimum bucket size Introduction 1 39 Introduction 1 7 RMS Utilities To invoke this utility use the following DCL command line format EDIT FDL fdl filespec The fdl filespec parameter specifies the FDL file you want to create modify or optimize For more information about the Edit FDL utility see the OpenVMS Record Management Utilities Reference Manual 1 8 Process and System Resources for File Applications To use RMS files efficiently your application requires various process and system resources You may have to adjust specific resources and quotas for the process running a file application Before using RMS options you should consider their impact on process and system resources In some cases you may need additional
508. yntax allows multiple system directory trees to exist on a single system volume You specify rooted directory syntax using a logical name in a program specified file specification or in the device and directory for a SET DEFAULT command If a program specifies a logical device name in the file specification the logical device name can be redefined to specify a rooted directory logical name Redefining the logical device name to specify a rooted directory changes the directory and the file or files accessed by the program without modifying the program If a program does not specify a logical device name in the file specification the user or a command procedure can issue DEFINE commands and the SET DEFAULT command before running the program to indicate the use of rooted directory syntax and to specify the process default device directory Using the SET DEFAULT command changes the directory accessed by the program without requiring that you modify the program When the program finishes use the SET DEFAULT command again to specify the new process default device directory and to resume the use of normal directory syntax if desired Using rooted directory syntax as illustrated in the preceding text provides several advantages Because you did not modify the program you avoided having to recompile or reassemble relink or retest it Another advantage is that because you were able to run the program from its resident directory you eliminated
509. you have enabled the gathering of statistics you can selectively use the Monitor utility to view them You normally enable statistics gathering prior to opening a file and then turn on the Monitor utility periodically to measure file performance as desired However the Monitor utility can begin monitoring a file even before an application opens the file In all cases the following restrictions apply to statistics gathering e All other processes accessing the file must close the file before you can enable statistics gathering e Statistics gathering is not supported for ODS 1 disks e You cannot collect statistics for process permanent files If a file is opened for both process permanent activity and as a standard file the process permanent activity is not included in the statistics e Non RMS file activity is not included in RMS statistics 3 6 1 Enabling RMS Statistics You can enable statistics gathering in one of three ways e Through the DCL interface using the SET FILE STATISTICS command e From a program through the Create service using a XABITM macro e Through the FDL interface by assigning the FILE secondary attribute FILE MONITORING when creating the file The Monitor utility begins monitoring RMS statistics for a file even if RMS statistics are not enabled When the Monitor utility s display indicates a 0 in the Active Streams field for a file see the sample display in Section 3 6 2 one of the following conditions is t
510. ys or by relative record number The update if option replaces an existing record using the Put service when you choose random access mode When superseding existing records consider using this option to add records to a relative or indexed file A program can use the update if option to update a record in a sequential file that is being accessed randomly by relative record number Record Processing 8 3 Record Processing 8 2 Primary Services Be careful with automatic record locking when you use this option for a shared file because the Put service briefly releases record locks applied by the Get or Find service before the Update operation begins This could permit another record stream to delete or update the record between the time that the program invokes the Put service and the beginning of the Update service Consider using the Update service instead of the Put service with the update if option to update an existing record in a shared file When a file contains alternate keys with characteristics that prohibit duplicate values the application must be prepared to handle duplicate alternate key errors For more information about the Put service refer to the OpenVMS Record Management Services Reference Manual 8 2 3 Updating Records The Update service modifies an existing record in a file Your program must first locate the appropriate record and optionally retrieve the record itself by calling either the Find service or the Get s
511. zed on magnetic tape in the order in which they are entered that is sequentially Characters of data on magnetic tape are measured in bits per inch bpi This measurement is called density A 1600 bpi tape can accommodate 1600 characters of data in 1 inch of recording space A tape has 9 parallel tracks containing 8 bits and 1 parity bit A parity bit is used to check for data integrity using a scheme where each character contains an odd number of marked bits regardless of its data bit configuration For example the alphabetic character A has an ASCII bit configuration of 100 0001 where two bits the most significant and the least significant are marked With an odd parity checking scheme a marked eighth bit is added to the character so that it appears as 1100 0001 When this character is transmitted to a receiving station the receiver logic checks to make sure that the character still has an odd number of marked bits If media distortion corrupts the data resulting in an even number of marked bits the receiving station asks the sending station to retransmit the data Even though a tape may have a density of 1600 bpi there are not always 1600 characters on every inch of magnetic tape because of the interrecord gap IRG The IRG is an interval of blank space between data records that is created automatically when records are written to the tape After a record operation this breakpoint allows the tape unit to decelerate stop if necessa

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