HP Integrity NonStop Service Information User's Manual
Contents
1. higher priority workloads Hewlett Packard Development Company L P 6 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 6 Disk Scan Checks When you use the SCAN option the validation examines the data on both drivesof the minored pairand ensures that the blocks have valid checksums If both the primary and minor drives contain invalid checksums an enor is reported for the file in question If one drive hasa valid checksum and the other drive hasan invalid checksum the good data is rewritten to the drive with the invalid data and the checking continues If neither drive contains invalid checksums the data is compared and any mismatch results in an enor reported to the user which identifies the location of the mismatch To limit the scan to the primary orthe minor drive use the PRIMARYSCAN or MIRRORSCAN option in the place of the SCAN option When you specify either of these options the scan validates checksums on the specified drive If the otherdrive isavailable it is used for checksum error recovery if the checksum is valid on that drive When you use the FASTSCAN option the validation only compares the data on the two drivesof the mirrored pair Any mismatch is reported to the user You can specify FULLSCAN to perfom both scan validation and data validation When you use FULLSCAN the scan validation is performed first followed by the structure validation Note Neither the SCAN northe2. scan before you remove SCF STOP one half of a mirrored pair In addition to the SCAN option FC HEC K supports the SCANPRIMARY and SCANMIRROR options FCHECK SCANMIRROR FINDBAD VOL DATA Ifa checksum enor isdetected on the specified drive the driver attempts to read the data on the nonscanned drive If that data hasa valid checksum the driver automatically rewntes the data to the drive with the defective data Otherwise the scan doesnot read the data on the drive that wasnot specified Hewlett Packard Development Company L P 30of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 This scan is particulary useful when a drive is suspect orthe subject ofa smart trip waming By scanning only the good drive the scan is less likely to result in a complete failure of the suspect orsmart tripped drive Always considera disk scrub of the mirrored pair before you stop any drive associated with the mirored pair These conditions include Drive replacement Stopping one drive of each minored pairasa fallback postion Drive upgrade Migratory revive to a disk drive in an ESS or Fibre Channel disk drive enclosure O00 0 Performing a disk scrub will reduce the possibility of data loss associated with the lossof the mirored protection Hewlett Packard Development Company L P 4 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 4 FCHECK SIZ Option Before you perform a migra
3. DP2 FC HECK User s Guide August 25 2005 DP2 FC HEC K User s Guide 1 Introduction FC HEC K isa Guardian program that checksthe intemal consistency of Disk Process 2 DP2 structured files It does not corect any of the structural problems it finds You can use FCHECK to verify the consistency of standard Format 1 and large Format 2 files Note The older DP2 tool FILC HECK doesnot work on Fomat 2 files After you install G 06 24 you can also use FC HECK to o Validate mirrored drive consistency You can use the SCAN option to verify the checksum of the source and target drivesand to ensure that the data on both drives of the mirrored pair isthe same If one of the driveshasa valid checksum and the other drive hasan invalid checksum the SCAN option automatically copiesthe data with the valid checksum to the drive with the invalid checksum o Determine the space requirement for migrating data from intemal 514 sector volumes to 512 sector volumes Before initiating a migratory revive use the SIZ option to report the current space used on the volume and the amount of space required to migrate the data to ensure that a disk drive in an Enterprise Storage System ESS or Fibre Channel disk drive enclosure is propery sized If space is not sufficient the migratory revive will abort FC HECK validation is actually performed in DP2 FC HECK drivesthe validation and reports the enors You can run FCHECK concunently with any appl
4. FASTSCAN option performs the structured data validation Scan validation is performed forall file types including unstructured files FC HECK errors displayed during a scan validation include Checksum 300 Medium 311 Compare 313 FC HECK might also report other errors but they are typically related to path lossora down drive Check Event Management Service EMS logs for disk subsystem events related to such enors Hewlett Packard Development Company L P 7 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 7 Structured Data Validation When the SCAN or FASTSCAN options are not specified FCHECK performs structured data validation FC HEC K will prompt DP2 to examine each block to ensure a proper structure which must be consistent for the file ortable type If the NOBITREE option is not specified DP2 examines key sequenced B tree structures to ensure that the B tree is consistent DP2 examines the file ortable sequentially and preemptsthe data validation if higher priority work is present FC HEC K uses the RATE value to pause between preemptions to limit the impact on active production When DP2 encounters errors EMS events are generated and FCHECK reports the details of the errors Hewlett Packard Development Company L P 8 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 8 FCHEC K Output FC HEC K providesa visual report for broken key sequenced B
5. Library DP2 FC HEC K User s Guide August 25 2005 2 Data Scrubbing Asa general guideline run FC HECK periodically to ensure that data is valid and consistent You can initiate FC HECK routinely during nonpeak penodsto cover entire volumes or limit it to critical data sets When you run the FCHEC K utility without a SCAN option and without the JIZE option a full validation of the structures is performed for any target structured files The validation is typically performed in response to certain application emors especially emor 59 and includes key sequenced B tree consistency and block headerand trailervalidation Data scrub can be an intense operation requiring significant CPU and I O cyclesto validate the data Consider disk scrub for routine scrubbing requirements with ad hoc orlessroutine data scrub to validate key data sets FC HEC K also allows you to validate unstructured files with data scrub to ensure that such files are readable Use disk scrub instead if the only files in the set are unstructured files 3 Disk Scrubbing For mirrored volumes HP recommends using the SCAN option for penodic disk scrubbing You can use NETBATCH ora similar product that automatic ally initiates one or more FCHECK validation scan operations during nonpeak periods Forexample you might execute this command for key disk volumes once each night or weekend FCHECK SCAN FINDBAD VOL DATA HP strongly recommends that you perfom the
6. ed RSN 0 Flags 7100000 Expected Flags 7006400 Records 31309 Error Recnum Blk Level 0 File Levels 0 Prev RSN 1 Next RSN a The block code equates to an intemal symptom string generated by the disk process and istranslated in the last line of the preceding display In this case the block flagsdo not match what is expected Hewlett Packard Development Company L P 11 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 Fora broken B tree structure FC HECK displays gt gt gt KS B tree error Block RSN 24 Expected RSN 24 Flags 3006000 Expected Flags 3006000 Records 33 Error Recnum 32 Blk Level 0 File Levels 3 Prev RSN 16 Next RSN 64 Level Prev RSN RSN Recnum Next RSN 02 8 0 01 1040 T Index rec 1 0 lt lt 32 gt Index rec 1 This display showsthe index pathsthat lead to the data block block levels and the data block chains previousand next This infomation can aid manual recovery of the broken B tree and provide some diagnostic infomation to help manage the problem If you cannot recoverthe broken data with some fom of file recovery method such asrestore or TMF recovery you might be able to corect the broken structure manually or use the FFIX utility to rebuild the structure in place If the structure needsto be comected manually contact your service provider for assistance 10 Physic al Disk Integrity Validation You can use FCHECK SCAN asthe key pa
7. ication The DP2 volume process performs data validation Asa result application activity does not interfere with consistency checks Hewlett Packard Development Company L P 1 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 This user guide is organized as follows Section Tite Describes 1 Introduction When to use FCHECK 2 Data Scrubbing FC HEC K data validation 3 Disk Sc rubbing FC HEC K disk validation 4 FC HEC K Size Option FC HECK capacity checks for migration of data from 514 sector disks to a disk drive in an ESSor Fibre Channel disk drive enclosure 5 FC HEC K Syntax How to run FCHECK 6 Disk Scan Checks Disk scrubbing validation checks 7 Structured Data Data scrubbing validation checks Validation 8 FC HEC K Output How to use the infomation retumed by FCHECK 9 Detailed Infomation How FC HECK reports problems with a for Broken Files file 10 Physical Disk Integrity FC HECK SCAN and Automatic Sector Validation Reallocation Appendix Outstanding issues You can acquire and use the FFIX utility to rebuild the B tree structure in place fora broken file ortable partition You must alter the partition to a nonaudited state before you run the FFIX utility and exclusive access is required For assistance with using the FFIX utility contact your service provider Hewlett Packard Development Company L P 2 of 13 NTL Support and Service
8. lett Packard Development Company L P 5of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 5 FCHECK Syntax FCHECK RATE nnn options FILE file VOL volume SUBVOL subvolume Le rv HELP RATE controlsthe rate at which the file checking is performed The minimum value is 1 Slowest and the maximum value is 100 fastest The larger the specified value the greaterthe impact on system performance options any combination of the following options separated by spaces Q Quiet mode S Summary mode J Provides infomation on space usage FINDBAD Combines Q and S FIXEO F Reduces EOF to exclude blocks with invalid checksums NO BTREE Skips B tree checks for key sequenced filesortables SCAN Performs scan check FASTSC AN Performs scan check without checksum validation FULLSC AN Performs scan check followed by data validation SC ANPRIMARY Performs scan check of only the primary drive SCANMIRROR Performs scan check of only the minor drive Use one of the following options to specify the file set s to be checked by FCHECK FILE system volume subvolume ffiename VOL system volume SUBVOL system volume subvolume Checkall filesin the current volume subvolume HELP print this information You can specify FILE volume SYS00 DIRECTRY to check the directory To limit impact to higher priority workloads initiate FC HECK at a priority less than the
9. oken files 0 Structured xsums 0 Files not checked open error FC HECK might encounter various failures when attempting to open a file for validation While the summary showsthe number of instances of open emor 12 all open erorsare included in this count including eror 12 In some cases open enors might be transient In othercases the open enor might be persistent Forexample if an audited partition requires HP NonStop Transaction Management Facility IMF volume recovery the error persists until the recovery is perfomed If the eroroccursbecaus a redo oran undo operation isneeded you can use the SNOOP utility to reset the recovery flags which will allow FC HECK to open the partition Use this procedure only if volume orfile recovery has failed to recoverthe partition Other possible causes for open enors include o Reserved file name o Conflicting open o Active NonStop SQL MP or NonStop SQL MP Structured Query Language SQL Data Definition Language DDL operation Hewlett Packard Development Company L P 10 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 9 Detailed Information for Broken Files The FC HECK utility displays information about three major file struc ture problems o Broken block o Blockchecksum eror o Broken key sequenced B tree structure Fora broken block headeror block checksum eror FC HECK displays gt gt gt Bad Block code BLK 19 Block RSN 0 Expect
10. rt of a regularly scheduled disk data integnity validation As described earlier FC HECK SCAN finds all sector checksum problemsand automatically these problems when one of the drivesof the mirored paircontains valid and checksum enor free data In addition if T8109 Automatic Sector Reallocation isenabled running FC HECK SCAN causes every in use sectoron both halvesofa logical disk to be read The DP2 driver automatically reports any media errors encountered during thisscan and the T8109 reallocation recovers the data from the good copy Asa result media erorsare reported and automatically corrected if possible whenever you run FCHECK SCAN Hewlett Packard Development Company L P 12 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 FC HEC K SCAN results are also reported to and cause an alarm on the HP NonStop Open System Mangement OSM interface You can use FCHECK SCAN inside an HP Tandem Advanced Command Language TACL macro orotherautomatic mechanism Because OSM alarms show any problems that could not be fixed you can then use these alarmsto help you correct the problems When the problem is corrected you can delete the alam or rerun FC HECK SCAN to confirm the repairand update the OSM alam status Hewlett Packard Development Company L P 13 of 13 NTL Support and Service Library
11. tory revive from a 514 byte sector disk to a disk drive in an ESS or Fibre Channel disk drive enclosure run FC HEC K S to ensure that the drive drive has sufficient capacity to handle any possible increased space requirement The syntax for this operation is FCHECK SIZE VOL DATA FC HECK examines the volume directory and reports the current usage for volume metadata structured files and unstructured files In addition FC HEC K providesthe amount of space required to migrate the entire volume to a disk drive in an ESSor Fibre Channel disk drive enclosure The first section of this report shows curent allocated space and the second section shows the required allocated space forthe target disk Disk space usages on volume in MB Maximum space 4963030 Meta data 376 Structured data 1897 Unstructured data 4960757 Allocated space 11043 Meta data 2 Structured data 23 Unstructured data 11018 To revive data to an ESS JBOD disk the target disk needs disk space for Maximum space 5693004 Meta data 378 Structured data 1897 Unstructured data 5690729 Allocated space 12671 Meta data 4 Structured data 23 Unstructured data 12644 The maximum amount of space reported isbased on full allocation of all files on the disk volume There istypically no reason to size based on this value but the information is provided to ensure that the disk has sufficient Capacity forany expected increase in space requirements Hew
12. tree structures based on the enors that DP2 detects Thisdata showsthe inconsistence in the b tree When no emorsare encountered FCHEC K reports the following information FileCheck S SYSTEM SYS20 TEMPLATE 2003 03 31 07 19 Version File format version Standard Blocklen 4096 Reclen 510 Keylen 30 Disk I Os 87 Data blocks 1293 Index blocks 22 Bitmap blocks 1 Elapsed time 0 66 seconds FileCheck did not find errors Note The last line is displayed afterall fillesare checked If you specify the Q quiet option only the last line of the report appears FPileCheck did not find errors x If you specify the S Summary option each checked file isreported as either corect Ok or broken File Ok SSYSTEM SYS20 TEMPLATE x FileCheck did not find errors x x If any errorsare found the last line of the report is FileCheck found broken files If you specify the FINDBAD option any bad filesare reported as File Bad SDATA22 GDUMPS TEMPLATE x FileCheck found broken files x Hewlett Packard Development Company L P 9 of 13 NTL Support and Service Library DP2 FC HECK User s Guide August 25 2005 An FC HEC K summary display includes the following information FCHECK findbad vol S data0l DP2 File Check Server FCHECK T9208G11 15MAR2004 File check summary Files checked 2876 Files skipped 0 Open error 12 8 Enscribe files 2882 SQL tables 2 Br
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