SCSI DataScrubber™ - SCSI Toolbox, LLC
Contents
1. Miscellaneous SCSI Issues SCSI Standards Lis sets Mes es SCST Cabling sieste nee HHNPHAQHKHHAH Simple Peripheral Installation Guidelines Appendix A Request sense Sense Rey Interpretatlron a RU ER atte augu ea eee ei te Ue RD UR E ea eae eee ees RUE GL re CEU ee 19 19 20 20 20 20 21 21 21 22 22 23 23 23 24 24 24 25 25 26 26 26 27 28 28 29 31 31 32 32 34 37 Chapter One The SCSI DataScrubber The SCSI DataScrubber runs under the DOS SunOS 4 1 x Solaris 2 3 and IRIX operating systems It utilizes a Motif style Graphical User Interface GUI to provide an easy and intuitive operator interface The SCSI DataScrubber consists of a loadable device driver if needed an application executable and a X11 resource file for customizing the user interfac The SCSI DataScrubber provides a means to completely erase all data from a disk drive Three different data patterns are written to every block on the disk including all blocks that are used as alternate blocks and all blocks held in reserve for flaw remapping For each of the three data patterns each block on the drive has the pattern written to it then the block is read back and each byte is compared to be sure that it matches the data pattern By the time the function is complete every byte on the drive has had the following patterns written and confirmed All Ones All Zeros2. set for any user who These variables are to the directory in application programs lled nt to the file which was copied into the SDSHOME directory during the installati on process IRIX Installation System Requirements The SCSI DataScrubber software requires an X11 windowing system to be operational on the workstation It also requires the dev scsi devices to be present on the workstation Loading Distribution Media The installation should be performed when logged in as the root user The next step is to create the installation directory on your computer this directory may be located anywhere mkdir install directory Now move to the installation directory by typing cd install directory The SCSI DataScrubber software is supplied in tar format Use the following commands to load the distribution media For tape distribution mt t tape device name rewind tar xvpf tape device name Running the STB install Script Now run the install program STB install The install program will ensure that the necessary device files are present on your system and create them if necessary It will then ask for a path into which to copy the application files create that directory if necessary and copy the program files into it Installing the Application Program The SCSI DataScrubber program executable file is copied into the application directory during the above instal
3. alternate blocks on the drive and in writing and confirming every data block on the drive the 16 purge function can take a long time to complete In cases involving very large capacity disks it will be necessary to let the purge run overnight to complete Because the progress of the purge function is monitored and tracked in the PURGE DAT file it is not necessary for the user to intervene in the purge process The faster the adapter the more quickly the purge process will complete A sample PURGE DAT file is shown below illustrating the purge operation on a small Seagate disk In this example the disk identification was entered as 20 mb seagate and the verification block was 432 SEAGATE ST138N 20 mb seagate 204 Spare Blocks Remapped Zeros written to all spare blocks Ones written to all spare blocks Random data written to all spare blocks Reallocating Spare Blocks Zeros written to all data blocks Verification Block 4 432 Data 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 17 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0
4. the dialog will continue until a transfer rate is agreed upon between the two devices Once a transfer rate has been negotiated whenever data is transferred it s clocked out at that data rate The two devices know how many bytes of data were supposed to transfer and each device will toggle its handshaking line that many times while counting the handshaking line from the other device As long as the number of handshakes agrees with the number of bytes transferred everything is fine and of course the data transfer happens in less time In order to do sync type transfers both the SCSI hardware and the host SCSI device driver must be designed to do so The Status Phase The status phase is used for the target to let the initiator know if a command was completed successfully or not If a command does not complete successfully the initiator can issue a 36 REQUEST SENSE command to ask the target what went wrong The sense data returned will describe the problem and hopefully point the way to a solution The Message Phase The message phase is used for several functions such as sync transfer negotiations signaling command complete telling the host to save data pointers disconnecting reconnecting and many others This allows initiators and targets to learn about each other and optimize performance SCSI Commands While the SCSI controller chips take care of Switching between bus phases and h
5. 2 revision was released in 1992 and incorporates wide SCSI which permits 16 or 32 bit parallel transfer using two cables Combined with the fast SCSI option data transfer rates up to 40 megabytes per second are possible Active termination was also specified for this standard The SCSI 3 revision is releasing in 1993 New features have been suggested and are being implemented to improve the SCSI 2 revision Improvements include the ability to address 32 devices a single 16 bit data bus cable and a serial SCSI protocol 43 SCSI Cabling The Small Computer System Interface SCSI is now being used by faster and more complex devices Th SCSI interface and associated ANSI standards are very flexible and allow for faster transmission rates A major limiting factor to higher throughput and data integrity is SCSI cabling SCSI cables must be engineered correctly in order to handle the increased transmission rates of today s SCSI devices Over the years that STB has been involved with SCSI products and enhancements experience shows that more than 80 of the problems with a new installation of external SCSI based devices disk drives tapes optical drives etc have been related to the SCSI cables used in the installations Ten percent of the problems relate to improper termination and five percent with software improperly installed With modern SCSI devices only a small
6. ID number for which it was set 48 Next try swapping cables experiment with different termination changing one may be a conflict or the between units and combinations of element at a time There term power level may not be sufficient In the latt r case you may have to add a terminator to the host adapter or even to another device on the chain 49 Appendix A Request Sense amp Sense Key Interpretation Sense Key Description Oh NO SENSE Indicates that there is no specific sense key information to be reported for the designated logical unit This would be the case for a successful command or a command that received CHECK CONDITION or COMMAND TERMINATED status because one of the filemark EOM or ILI bits is set to 1 1h RECOVERED ERROR Indicates that the last command completed successfully with some recovery action performed by the target Details may be determined by examining the additional sense bytes and the information field When multiple recovered errors occur during one command the choice of error to report first last most severe etc is device specific 2h NOT READY Indicates that the logical unit addressed cannot b accessed Operator intervention may be required to correct this condition 3h MEDIUM ERROR Indicates that the command terminated with a non recovered error condition that was probably caused by
7. LICENSED PRODUCT WHETHER IN ACTION IN CONTRACT OR TORT INCLUDING NEGLIGENCE LIMITED WARRANTY AND DAMAGES DISCLAIMER Subject to the conditions and limitations on liability stated herein STB warrants for a period of ninety 90 days from the delivery of the first copy of each type of SOFTWARE as so delivered will materially conform to STB s then current documentation for such SOFTWARE This warranty covers only problems reported to STB during the warranty period ANY LIABILITY OF STB WITH RESPECT TO THE SOFTWARE OR THE PERFORMANCE THEREOF UNDER ANY WARRANTY NEGLIGENCE STRICT LIABILITY OR OTHER THEORY WILL BE LIMITED EXCLUSIVELY TO PRODUCT REPLACEMENT OR IF REPLACEMENT IS INADEQUATE AS A REMEDY OR IN STB S OPINION IMPRACTICAL TO REFUND OF THE LICENSE FEE EXCEPT FOR THE FOREGOING THE SOFTWARE IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND INCLUDING WITHOUT LIMITATION ANY WARRANTY OF FITNESS OR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE FURTHER STB DOES NOT WARRANT GUARANTEE OR MAKE ANY REPRESENTATIONS REGARDING THE USE OR THE RESULTS OF THE USE OF THE SOFTWARE OR WRITTEN MATERIALS IN TERMS OF CORRECTNESS ACCURACY RELIABILITY OR OTHERWISE The Licensee understands that STB is not responsible for and will have no liability for hardware software or other items or services provided by any persons other STB STB shall have no liability for delays or failures beyond its reasonable control STB SHALL NOT BE RESP
8. Roe e se aV EA fure Chapter Five DOS vErodgram ExXSCUEL OB 4 5949 e Guest ie ne a NETUS eo eager a ise ovr eue A eet a aede Gen DE SR ove Gee Ee wae Este Scanning the eS OS Te BUS Cui ede voeem ae deste qid se Iud aue be a has decis Dio aa eoe Meier ates ata ce foem ane eds ves e e Mer E BULGER Pro getto A D LR RS Ne Tome er teas in Lepus deo Ux a Rosa ne deer ee Dune ease in oae on ia ensue ve PANG Bose e eae emer ie as et dd COMMON P GDL MS ei PvP PU rrr PP ERAMOS rm EE La a Ka A A G O I I L L H H H H H OO I I I LU XO O iO 1 d d d GN Oo 01010101 P2 ND PO DN PO N NN Chapter Six SCST T toriaLk suce poses more ste or sa Introduction to SCSI Philosophy SCSI Hardware ic ices mue ie iles Data DINES cue vete e ets Control Mines he ee CCS Single ended SCSI Single ended Termination Differential SCST wj xx Cables and Connectors SCST SOLCWA LE eld metuens SCSI Bus Phases i he Bus Free Phase he Arbitration Phase he Selection Reselection Phase he Command Phase ommand Descriptor Blocks DB Format Voter e dee et he Data In Out Phase synchronous Transfers ynchronous Transfers he Status Phase he Message Phase SEST Commands demie tre hie le E SCSI Bus Operation An Example Typical SCSI Operation Disconnect ui Mere id Disconnection Notes
9. SCSI problems The 3 meter and 6 meter length limits suggested for 10 and 5MB per second transfers Fast SCSI 2 and SCSI 1 respectively are aimed at eliminating potential data problems on the SCSI bus With many integrators not readily able to provide Specifications as to how their cables are constructed it is usually very hard to determine if the purchased round SCSI cable will work error free in the target SCSI environment There are SCSI round cable suppliers providing cables with connectors that though specified as SCSI 50 pin cables may have as few as 25 lines wired from connector to connector Differential applications will not operate under these conditions and many single ended SCSI applications will also have trouble maintaining uncorrupted signal transmissions with cable more than 6 feet long as most of the ground lines are 45 not connected Even if all of the wires are connected and even if twisted pair cable made specifically for SCSI is used depending upon how the cable is wired to the connector there can also be problems The twisted pairs on the cable must be matched with the correct pin numbers Otherwise it is possible to have the plus side of two signal lines going through the same wire pair inducing interference between the signals This causes problems on fast SCSI based systems and systems with longer SCSI cable lengths As is the case also with SCSI terminatio
10. and alternating Ones and Zeros A user selected block on the drive is designated as a verification block The data on the verification block is printed out after each data pattern is written to give a confirmation of what data is now Stored on the drive A disk file called purge dat is created that contains a record of the purge process This file contains a journal type report of the progress of the purge The verification block data is printed to this file after each of the three data patterns is written as a confirmation that all data on the drive has been erased Chapter Two SCSI DataScrubber Installation SunOS 4 1 x Installation System Requirements The SCSI DataScrubber software requires an X11R5 or OpenWindows windowing system to be operational on the Workstation It will operate with the OpenLook window manager mwm twm and many other window managers Loading Distribution Media The installation should be performed when logged in as the root user The next step is to create the installation directory This directory can be located in any file system on your computer The contents of this directory may be deleted after the installation is complete mkdir install directory Now move to the installation directory by typing cd install directory The SCSI DataScrubber software is supplied in tar format Use the following commands to load the distribution media For ta
11. host is expected to send is REQUEST SENSE This allows the target to return further status information to the host 7 The target completes the SCSI sequence by going to the MESSAGE IN phase and transferring a COMMAND COMPLETE message to the host The target then releases BSY allowing the bus to go to the BUS FREE state Disconnect In order to improve bus usage and performance many SCSI devices are capable of disconnecting from the host in order to free the bus to allow other requests to be sent to other targets To do so however the host needs to support Disconnect Reselect If Disconnect is implemented the procedure is as follows 1 The host arbitrates for the SCSI bus and if it wins it selects the target device Befor releasing SEL and completing the selection phase the host asserts the ATN line The host then releases SEL and BSY The target now has control of the SCSI bus By asserting ATN the host has indicated that the target should go to a MESSAG OUT phase LS 2 After the SELECTION phase is completed the target responds to the host s ATTENTION condition 39 by initiating a MESSAGE OUT phase It receives a message from the host which tells it whether the host can support Disconnect Reselect and the desired logical unit number on the target 3 The I O activity from this point is contr
12. qve h ANS retis uero qe ote a tel erue qure s tese ete darlene TMS qeu Comp Penang secte EIS tad AC TOME SR nain se SN dos SER bs eed le dae edge telles Qa o ete cotidie Ae ae Dori e deae e 2d Copy Inmo tae DASE ER MON DIS eget eiue cet iet supere ete LE IUS Mah ARS Pn ds SUR dass duree Chapter Three UNIX Main Window Command Line Syntax wea Maiden x9 ds a ee A en Sn ee ea Rides s Menu Bo v iure Ice Row EVA RUE e e pc coeur acie Det BRUNE E Vole A A ess en EAS EUREN A eee he APE Select Device WEA a dA dard Leer dee oc ies jie deeds SR osse meets ARTN ne ARS eo haar rie ide SUN ME Mem tte ROS te Lock Target MENU cca eme ne cuu e oa ex ecu E RU A EIUS EXER prede s end UNE RU E eX CE EHE pese even St ERU NE SMa ERE VA Ue ce Vas EHE RUE eo Program L ANLMAOMNE Ta ia aUe PAD A E Sue bentur eue fo ard ped er Mer CE E lohan cert aus ules ince on nd Tonks Status LINE e 2 A A educ quA A Eo S Mies due SNS A A A tossed Aue Lie tt a ee de Command Line Vee SPONGY NCA eis uper dap sr eue sexe Bess do Doe ROS ctr dv e Que cts tuae pes bp R at al aan Dae Re ee a a Chapter Four ONE AIRES ET MENU SR des a eiat ted ei cene ardens a de EE a le Dee Man ee eaae ten io C ne attend pde iraq eh tx tM e tof fonte e de aaa aaa ot QUIER OCA LES EN O A ee feta desee m te a o pate ce tata trees eed qa adit pde ete d SEN Past ut Ere de rU etd Lee PULSE N vae ex te ole RTS uere rS eb Re dues sete ao etu truc dates A uu uses
13. ready to do something else The host remembers that it started an operation with this peripheral but that the operation is not finished yet When th tape drive is ready it will use the SCSI reconnect phase to tell the host Hey I m back now The host will then pick up where it left off finishing the command The Command Phase The command phase is used to send a command code from the initiator to the target This command code is made up of a number of bytes grouped into a data packet called a Command Descriptor Block CDB Command Descriptor Blocks A CDB can be 6 10 or 12 bytes long These bytes describe the command to the target including information about any parameters that the target needs to execute the command If more information is needed than can fit into the CDB additional data blocks can be sent to the target Thes additional data blocks are sent using the Data phase of the SCSI bus CDB Format The basic format of a six byte CDB is as follows Bit 7 6 5 4 3 33 Byte 0 Operation Code 1 LUN Logical Block MSB 2 Logical Block Address 3 Logical Block Address LSB 4 Transfer Data Length 5 Control Byte Flag Link The operation code defines the command The most basic SCSI command is the Test Unit Ready command and its operation code is 0 The CDB for the Test Unit Ready command is 00 00 00 00 00 00 This command does not transfer any data therefore the logic
14. the install sds program and are specific to the SCSI target number specified The user does not need to know these device names as the SCSI DataScrubber program handles the file names internally Any user account which will be running the SCSI DataScrubber application will need read and write access to the stb device files The load script created above will assign read and write access to all users If the system manager does not desire all users to have this access the load script can be modified as needed Installing the Application Program The SCSI DataScrubber program executable file is copied into the application directory during the above installation process This file stb can be executed from there Also included with the distribution is a default application resource file Xstb Copy this file to the home directory of any user who will be running the SCSI DataScrubber program or install it in the app defaults directory used by your windowing system Required Environment Variables The SCSI DataScrubber program requires two environment variables to be set for any user who will be running the program These variables are SDSHOME Set to point to the directory in which the application programs were installed XKEYSYMDB Set to point to the file XKeysymDB which was copied into the SDSHOME directory during the installation process Solaris 2 x Installation
15. well as receive data from the device The Data In Out Phase The data phases are used to transfer data to or from the initiator This data can be additional command parameters such as Mode Select data or defect data or it can be actual user data Data transfers can happen in two different ways Asynchronously or Synchronously Asynchronous Transfers hen a SCSI subsystem transfers data from a eripheral to a host there needs to be a way for eady for data or when they cannot receive data W p the devices to signal each other when they ar r This process is called handshaking The peripheral t hat is receiving the data tells the sender when it is ready and the sender always waits until it 35 is told to send data With Asynchronous SCSI this handshaking process happens with each and every byte of data The sender says I ve got some data for you then waits for the receiver to say O K send it over This process happens with every byte sent including SCSI commands messages user data and status bytes Synchronous Transfers ith Synchronous transfers the target and the initiator decide beforehand how fast they can talk Using the SCSI message phase a device will ask another device Can you do sync transfers If the answer is yes one device will ask the other How fast can you transfer If the reply is Five megabytes per second but the first device can only run at 4 6 MB sec
16. 0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 18 Ones written to all data blocks Verification Block 432 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
17. 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 21 Purge Complete 22 Chapter Five DOS Program Execution Help By typing purge cr at the DOS command line the DataScrubber Help Menu will be displayed This menu will explain all available DataScrubber options Scanning the SCSI Bus By typing purge s at the DOS command line the program will scan the SCSI bus and display information about all devices connected to the bus The manufacturer part number device type and the capacity and block size in the case of disk drives will be shown next to the SCSI Target number This function is useful to confirm that the device that you intend to purge is connected at the SCSI address that you think it is Viewing Disk Defects The disk drive defect list can be viewed or saved to a file by typing purge gi cr where is the Target number of the SCSI disk at the DOS command prompt You will be asked whether you want to see P G or both P amp G lists the list format and if you d like to view the defect data on the Screen or save it to a file If you choose to save the data to a file you will be asked to enter a file name Purging a Disk By typing purge n where n equals the SCSI target you wish to purge yo
18. CSI DataScrubber hereinafter the LICENSED PRODUCT By opening the sealed media package on which this PRODUCT is distributed are agreeing to be bound by the terms of this agreement If you do not agree to the terms of this agreement return the unopened media package and accompanying materials to the place where you obtained them within 10 days from the date of shipment for a full refund This agreement supersedes all prior agreements proposals and representations between you Choice and STB LICENSE AND TERM STB and any applicable sublicensors grant to the LICENSEE a non exclusive non transferable license to use the programs and related documentation collectively referred to as the Software on licensed client processing unit s Any attempted sublicense assignment rental sale or other transfer of the Software or the rights or obligations of the Agreement without the prior written consent of STB shall be void This license will automatically terminate without notice if LICENSEE should fail to comply with its terms The Software and documentation are copyrighted Unauthorized copying reverse engineering decompiling disassembling and creative derivative works based on the Software are prohibited Title to the Software is not transferred to LICENSEE by this license Ownership and title to the Software including any copy of the Software and the associated documentation are retained by Choice LICENSEE shall have the right
19. FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF Data 6 E FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF EF FF FF FF FF FF FF pp FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FE FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF EE FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 19 20 Random data written to all data blocks Verif
20. I subsystem that does not support arbitration it can go to either the selection or re selection phase The Arbitration Phase In this phase SCSI devices can negotiate for access to the bus SCSI devices arbitrate by setting their ID number and the SCSI BUSY line If more than one device wants the bus the device with the highest SCSI address wins the arbitration and sets the SELECT line Arbitration is required in SCSI II implementations The Selection Reselection Phase In this phase the SCSI initiator selects which SCSI target it will talk to The SCSI initiator puts the bus in select phase and sets the address of the target Then it waits for the target to respond that it is there Once the target has responded to selection the target device will control the SCSI bus until the transaction is completed or until the target disconnects from the bus If the SCSI target determines that it will need 32 some time before it fulfills the request it will disconnect itself from the bus allowing the bus to be used by other peripherals For instance if a SCSI tape drive receives a command to space forward it will know that this is a time consuming operation Rather than make the host computer and other peripherals wait for it the tape drive can send a disconnect message to the host This messages effectively says I m going to be busy for a while I 11 let you know when I m
21. LA PE Las re sea ora aste Ec UPS eR heec Bia Er creme da A TE Cere E E Ihe Loddable Devliee DELIVER ls AA AUR SUR tue TRUE A Rude Sees Baty use v te e MO ent Geechee E RUE e E erp verde Sue ne Solaris zix TASEALILSELON ues segs en AS Ge eee ae hs Y Elea ere eee er e Leer Cree ep ue ec eii LE nue LE lur System R QULE MENES L ESS era T a tatu E a ANS a Uae PUS Neue Land rene eq aue Que E ee pue E E Erie LoaduimocsDsstcibutron Media seas dee E uice ede e sab SOR eda es Eee edo ih den dosi e i esi od Te E oes sare le Senden dont Ye rt cea does n Neo ie xat dd Runnzhg Ene STR lt iN Sta SGI DE nets ue eie men e queens does SIE FUE Poen PRI eme Tenue ala tin med E IUE Bane de Ihe boadabte Devreese D riyer Gc dan donne eme p te UR ghi ce ppt ee Geeta el A AA te A A AAA RUE PIED Dre dE gne s LnsStawslang the App is Cation P6ogramn divei3ceude x RA quee Rr eere ridet erroe e eerie erc uie ER e e e ete E s e rue EUER UE IRIXS IBnSteLlqtlioH se O uie zou eedem rodar ieu eve a io i SysctemsRedquitemetS serea ae AS A ne c TE Pasian Tel Ral got oe alte RP ESO N RUE Ate e Nt ua SG S Dist ER VON MEL LPS ames ied edu vere e edd eiut ES ute eo denos tiene d tires tees i den One e de hp eie RUNNING ENE SITB ns Calle SC EUDE Lausanne rq ure er ve uei tele te P Seeds ie A eise tele ta A Eo mE a S DOSa THS tad at ron ts eed iie ny e xS Rte E MESS anse ne AN e e Reus euo A suite M sus GU M Ege ume A ELE giri SVS PSM REGU emet Suae EU A at AS d en E coro a des eue
22. ONSIBLE OR LIABLE WITH RESPECT TO ANY SUBJECT MATTER OF THIS SOFTWARE LICENSE AGREEMENT OR THE AGREEMENT OF WHICH IT IS A PART OR ANY ATTACHMENT PRODUCT ORDER SCHEDULE OR TERM OR CONDITIONS RELATED THERETO UNDER ANY CONTRACT NEGLIGENCE STRICT LIABILITY OR OTHER THEORY A FOR LOSS OR INACCURACY OF DATA OR EXCEPT FOR RETURN OF AMOUNTS PAID TO CHOICE THEREFOR COST OF PROCUREMENT OF SUBSTITUTE GOODS SERVICES OR TECHNOLOGY B FOR ANY INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO LOSS OF REVENUES AND LOSS OF PROFITS OR C FOR ANY MATTER BEYOND ITS REASONABLE CONTROL This Agreement shall be construed interpreted and governed by the laws of the State of Colorado and by international laws and treaties governing copyrights patents and intellectual property rights Table of Contents Chapter One The SCSI DataSerubberiM 1 225243 Den mac oe aces e Seed Nue E Noe Ea Dee Sue dU NE Pussy desee don Sr de K R Bike CEES us ew Chapter Two SCS Dataserubber Anstal Lat Oty 245 are xu deae eR erate tows te Gate Aeneis pep iei ku eh deeem A te ee de de Ce due ters dede eue E SUNOS c4 Mx Insbaellatro H ta dns A Re Se Bee A eerie rare etre entrer de se ite eus System Redgur ements ass Loi a ter E OE ERE sale ue rece rues eee TET rure Vance recs e er esi ree err d en rss s dee eu DLoadtng bBbaiscr3ibutron MedLE ad A Re Eee e ete A A A a e e e den A wie ACE o ah ar alo ENSE LR EXER ics Running the STB TNS Paes SS C
23. SCSI DataScrubber Version 6 1 0 SCSI Toolbox LLC PO Box 620520 Littleton CO 80162 email support scsitoolbox com Copyright 2002 SCSI Toolbox LLC COPYRIGHT NOTICE Copyright 1994 by SCSI Toolbox LLC LLC STB All rights reserved This item and the information contained herein are the property of STB No part of this document may be reproduced transmitted transcribed stored in a retrieval System or translated into any language or computer language in any form or by any means electronic mechanical magnetic optical chemical manual or otherwise without the express written permission of SCSI Toolbox LLC P O Box 620520 Littleton Colorado 80162 DISCLAIMER STB makes no representation or warranties with respect to the contents of this document and specifically disclaims any implied warranties of merchantability or fitness for any particular purpose Further STB reserves the right to revise this publication and to make changes in it from time to time without obligation of STB to notify any person or organization of such revision or change SCSI DataScrubber is a trademark of SCSI Toolbox LLC Inc Manual Revision 6 96 LICENSE AGREEMENT This SOFTWARE LICENSE is an agreement made by and between SCSI Toolbox LLC hereafter STB and you the end user hereinafter LICENSEE This license agreement is for proprietary software owned by Choice Software Inc hereafter Choice and licensed by STB identified as The S
24. SI set up each end of the SCSI chain must be terminated If you have only internal or external devices on the bus the host adapter and last device on the chain should be terminated If you have external and internal devices on the chain you will generally terminate the first and last of these devices but not the SCSI host adapter 5 Making connections There are a variety of SCSI cable connectors 25 pin for SCSI 1 50 pin for SCSI 2 and 68 pin for the Wide SCSI Look at the connectors on the items you need to attach before you buy and be sure to obtain quality cables with good shielding Your best bet is to buy internal and external cables as short as possible but no shorter than one foot long to avoid signal noise 6 Check and test Turn on any external devices before booting your PC most external devices must be running to be recognized by their driver when the PC boots If a unit or the whole chain fails try the following Check the ID numbers and cable connections to make sure that peripherals requiring specific IDs are set for them and that all devices are appropriately connected Then power down and power up the system watching the messages during the initialization of the configuration files Make sure all drivers are loaded properly If you can isolate an offending device reposition it elsewhere on the chain If that fails change its ID number perhaps the device is just unable to work at the
25. System Requirements The SCSI DataScrubber software requires an X11R5 or OpenWindows windowing system to be operational on the Workstation It will operate with the OpenLook window manager mwm twm and many other window managers Loading Distribution Media The installation should be performed when logged in as the root user he next step is to create the installation T directory this directory can be located in any file system on your computer The contents of t his directory may be deleted after th H nstallation is complete mkdir lt install directory gt Now move to the installation directory by typing cd lt install directory gt The SCSI DataScrubber software is supplied in tar format Use the following commands to load the distribution media For tape distribution mt t lt tape device name gt rewind tar xvpf lt tape device name gt For floppy distribution tar xvpf dev fd0c Running the STB install Script The STB install script will uncompress and extract the files from the distribution format It will then prompt for necessary information as it performs the installation You will be asked which directory you want the application files installed into and asked for your authorization string The script will install the loadable device driver and copy the program files into the appropriate directory The Loadable Device Driver The loadable device driver is
26. a flaw in the medium or an error in the recorded data This sense key may also be returned if the target is unable to distinguish between a flaw in the medium and a specific hardware failure sense key 4h 4h HARDWARE ERROR Indicates that the target detected a non recoverable hardware failure for example controller failure device failure parity error etc while performing the command or during a self 50 5h 6h 7h 8h 9h Ah Bh Ch Dh test ILLEGAL REQUEST Indicates there was an illegal parameter in the command descriptor block or in the additional parameters supplied as data for some commands FORMAT UNIT SEARCH DATA etc If the target detects an invalid parameter in the command descriptor block then it shall terminate the command without altering the medium If the target detects an invalid parameter in the additional parameters supplied as data the target may have already altered the medium This sense key may also indicate that an invalid IDENTIFY message was received UNIT ATTENTION Indicates that the removable medium may have been changed or the target has been reset I DATA PROTECT Indicates that a command that reads or writes the medium was attempted on a block that is protected from this operation The read or write operation is not performed BLANK CHECK Indicates that a write once device or a sequential access
27. al block address and the transfer data length are set to zero Most SCSI commands will deal with logical unit 0 therefore the LUN field is also set to zero It is very hard to set an illegal parameter in the Test Unit Ready command since all of the parameters are zero A more complex command The SCSI INQUIRY command will transfer data from the device but it does not transfer the data from a data block on the device Instead it transfers the data from the device s controller The operation code for the INQUIRY command is 0x12 The CDB for this command is 34 T2 00 00 00 ff 00 The Oxff value in byte 4 of the above CDB specifies that we want to transfer up to 255 bytes of information If the device has fewer than 255 bytes to transfer this will not result in an error the device will send all of the data that it has and then signal that it is finished If we Specified a transfer length of 5 bytes and the device could have sent us 32 bytes it will only transfer the 5 bytes that we requested Many of the SCSI commands that have a data phase will return a data header or special information about how many bytes were transferred The basic CDB structure is the same for the 10 and 12 byte CDBs there is just more room in the command to specify a larger logical block address and a large transfer byte length The more complex SCSI commands will have additional data phases that will send additional information to the device as
28. andling all of the handshaking it is up to the system devic driver to assemble CDB s send them in the proper order and interpret the data returned by them The Command Menu in the SCSI Disk Optimizer allows you to send individual SCSI commands to the device under test and observe the results Understanding what SCSI commands are available and what those commands do is essential to successful SCSI troubleshooting Reading the Commands chapter of this manual and browsing through SCSI software manuals for the peripherals that you work with will give you a good overview of how these commands work SCSI Bus Operation An Example Typical SCSI Operation This example describes the typical SCSI bus sequence between a SCSI host initiator and a target in detail 1 The host arbitrates for the SCSI bus by 37 asserting BSY and the data line corresponding to its bus ID If any other devices wish to compete for the bus they also assert BSY and the appropriate data line Each arbitrating device then inspects the data bus and the device with the highest ID wins it All the other devices must release BSY and their data lines 2 The host attempts to select the target by asserting SEL and releasing BSY The host maintains its ID and asserts the target s ID on the data bus Each target then checks the data lines If the target s ID matches that on the data bus it accepts selection by asserting BSY Onc
29. ata transfer if the final transfer occurs on a disconnect boundary before initiating the STATUS phase This is intended to optimize bus usage Most devices do not disconnect on receipt of the following commands 41 INQUIRY REQUEST SENSE TES UNIT RE The drive wil ll discon ADY nect on other commands if it is programmed or configured to do so 42 Miscellaneous SCSI Issues SCSI Standards The SCSI standard describes the physical and electrical characteristics of a parallel I O bus used when connecting computers and peripherals in a daisy chained manner The connection of devices such as disk drives tape drives optical drives printers CD ROM drives and other devices without hardware modification is specified by the standard The SCSI bus provides two electrical Specifications single ended and differential The single ended driver and receiver configuration uses TTL Transistor Transistor Logic logic levels and is primarily designed for applications within a cabinet The single ended version uses cable lengths up to 6 meters 19 68 feet The differential driver and receiver configuration uses EIA RS 485 signals and is primarily designed for applications requiring longer cable lengths The differential version uses cable lengths of up to 25 meters 82 02 feet The original SCSI standard was approved in 1986 and was called SCSI 1 The SCSI
30. built by the install script and loads automatically on the first access after a reboot The device names are specified in the file etc devlinks tab which is edited by the install sds program and are specific to the SCSI target number The user does not need to know what these device names are as the SCSI DataScrubber program handles the file names internally Any user account which will be running the SCSI DataScrubber application will need read and write access the stb device files The install script created above will assign read and write access to all users If the system manager does not desire all users to have this access call tech support at STB for instruction on changing the file protection Installing the Application Program The SCSI DataScrubber program executable file is copied into the application directory during the above installation process This file stb can be executed from there Also included with the distribution is a default application resource file Xstb Copy this file to the home directory of any user who will be running the SCSI DataScrubber program or install it in the app defaults directory used by your windowing system Required Environment Variables The SCSI DataScrubber program requires two environment variables to be will be running the program SDSHOME Set to point which the were insta XKEYSYMDB Set to poi XKeysymDB
31. ce In the case of disk drives the SCSI Specification allows the drive itself to deal with defective blocks keeping track of spare blocks and remapping internally that is within the SCSI black box This means that even though a drive may have defective blocks the disk appears as a contiguous number of flawless blocks to the SCSI world This black box approach to data storage and retrieval makes the job of writing a universal device driver a fairly simple task For instance a disk device driver can accommodate drives of 27 virtually any size because the SCSI specification lets you ask a disk drive how many blocks of data it can hold And reading or writing data to a SCSI disk consists of simply telling the drive how many blocks you want to write what block number to start writing at then sending the data to the drive as the drive asks for it The device driver never knows physically where on the drive the data is going because the SCSI peripheral takes care of all logical block to physical geometry mapping As long as you do not try to read or write data beyond the highest accessible block number everything is fine As SCSI specifications have evolved support of input and output devices other than disk and tape have been added The SCSI 2 specification defines standard methods to deal with scanners printers and jukebox robotics The SCSI 2 specification also defines a hardware upgrade pa
32. ce mak sure that you know all of the existing SCSI identification numbers on the chain before you start installation If you have a host adapter that reports the IDs during bootup as the Adaptec AHA 1542C does the task is easy otherwise prepare to check the jumper or switch settings on each peripheral in the chain Or better yet keep an up to date easily accessible list of all the SCSI peripheral IDs on the chain as well as the I O address and BIOS Basic Input Output System location of the host adapter Devices with low number settings have a higher priority As a rule you ll want to set your first hard disk at 0 and your second hard disk at 1 Host adapters are generally set at 7 and some operating systems such as those that are Unix based expect to find them set there In certain cases some operating systems also expect other peripherals such as CD ROMs to hold specific IDs check your software and adapter manuals before installation SCO Unix for example expects a CD ROM to be located at ID5 If you ignore such rules the system may ignore your device 3 Internals first Try to install all your internal units first starting with hard disks But install them one ar a time and before you start experimenting with external devices and termination Adding an external device means you need to make a change in the devices that are 47 terminated 4 Observe proper termination In a SC
33. devic ncountered blank medium or format defined end of data indication while reading or a write once devic ncountered anon blank medium while writing Vendor Specific This sense key is available for reporting vendor specific conditions COPY ABORTED Indicates a COPY COMPARE or COPY AND VERIFY command was aborted due to an error condition on the source device the destination device or both ABORTED COMMAND Indicates that the target aborted the command The initiator may be able to recover by trying the command again EQUAL Indicates a SEARCH DATA command has satisfied an equal comparison VOLUME OVERFLOW Indicates that a buffered 51 E E peripheral device has reached th nd of partition and data may remain in the buffer that has not been written to the medium A RECOVER BUFFERED DATA command s may be issued to read the unwritten data from the buffer MISCOMPARE Indicates that the source data did not match the data read from the medium Fh RESERVED 52
34. e the host has detected BSY being asserted it asserts ATN to indicate that it will want the target to go to the MESSAGE OUT phase The host releases SEL 3 The target now has control of the SCSI bus and it is the target which switches between phases he target responds to the ATTENTION condition and nitiates the MESSAGE OUT phase The host sends an T i IDENTIFY message which tells the target which logical unit the host wishes to talk to The fact E t hat the target responds to the ATN indicates to he host that the target can accommodate more than just a COMMAND COMPLETE message 4 The target initiates the COMMAND phase and transfers the Command Descriptor Block from the host In the COMMAND phase the target decodes th command and either executes the command TEST UNIT READY or sets itself up for a data transfer to the host for example READ WRITE INQUIRY The target then either switches to the STATUS phase if the command is complete or DATA phase if it is ready to transfer data 38 5 The data transfer length is set by the host in the Command Descriptor Block The target remains in the DATA phase until all data is transferred 6 The target then initiates a STATUS phase and transfers one byte to the host to indicate whether it has completed the command successfully If the target has detected an error the next command that the
35. ication Block 432 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A Data 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A
36. lation process This file stb can be executed from there Also included with the distribution is a default application resource file Xstb Copy this file to the home directory of any user who will be running the SCSI DataScrubber program or install it in the app defaults directory used by your windowing system Required Environment Variables The SCSI DataScrubber program requires two environment variables to be set for any user who will be running the program These variables are SDSHOME Set to point to the directory in which the application programs were installed 10 DOS Installation System Requirements The SCSI DataScrubber program runs on any IBM PC that has an ASPI compliant SCSI adapter Adapters that have been tested with this program include those from Adaptec DPT Busteck Trantor Always Ologic Shining and Eclipse Since the SCSI DataScrubber program is an ASPI application you need to make sure that you have properly installed the ASPI software for your SCSI adapter Completing the Installation The SCSI DataScrubber program can be run from the supplied floppy disk drive or from a hard disk To load the program onto a hard drive simply use the DOS copy command to copy all files from the floppy disk to your hard disk Copying the Distribution Disk Feel free to make a backup copy of the original program disk and keep it in a safe place The SCSI DataScrubber program is NOT copy pr
37. levels on these pairs of lines move in opposite directions and both the high and the low lines are checked in order for their data to be valid This method provides its own noise cancellation and allows for cable lengths up to 25 meters Single ended SCSI to Differential SCSI converters are available otherwise you can not mix single ended and differential devices on the same SCSI bus Cables and Connectors Typically a raw SCSI device will have a 50 pin dual in line mal connector for its SCSI bus connection This type of connector has two rows of 25 pins spaced 1 apart The active SCSI signals are connected to the even numbered pins and the odd numbered pins are signal ground Most systems use a connection other than the 50 pin dual in line type Some use a DB 50 type connector some a 50 pin variation on the 30 Centronics type connector while others use a miniature version of the D type connector Some use only female gender connectors on their enclosures while others use male gender The SCSI Disk Optimizer uses a DB 25 female connector wired in accordance with the Apple Macintosh standard In other words there is not one standard for connections and cables in the SCSI world SCSI Software The SCSI specification describes a software protocol as well as a hardware definition An understanding of this software aspect of SCSI will be helpful when interpreting SCSI problems and errors A SCSI
38. n issues STB recommends careful examination of cabling specifications as part of a properly engineered SCSI environment Cabling problems present challenging and frustrating problems in the real world of SCSI Simple Peripheral Installation Guidelines SCSI gives new meaning to the term plug and play A single peripheral attached to a matching host adapter is usually easy to install but when you plug several into a single host things can get more complicated The SCSI 2 draft Specification universal drivers and easier installation routines go a long way toward making things easier But even so it s likely that you ll come up against at least one or two problems along the way Here are eight tips for getting your setup to go as smoothly as possible 1 Start simple Start with the basics Rather than plugging a chain of peripherals into a single SCSI card and then booting up and confronting the confusion and possible conflicts that are likely to result get the host adapter installed first and then install the first hard disk You will want to continue installing devices one at a time 46 checking to see that they are working before moving to the next This may seem like a bit of extra work you will have to install and reinstall device drivers for most of the peripherals for example but in a complex setup this is often a shortcut in disguise 2 Make a list When adding a new devi
39. ng a large data transfer the target may disconnect at intervals depending on its use of the bus The drive optimizes its use of the bus SO as to maximize the transfer rate when it is connected to the host and to minimize the time for which it holds the bus without handshakes If the target disconnects during a data transfer the target initiates a MESSAGE IN phase and send the host a SAVE DATA POINTERS message and a DISCONNECT message The host responds to the SAV DATA POINTERS message by saving the current data pointer After transmission of the DISCONNECT message the target releases BSY freeing the bus E 7 Once the target is again ready to reselect the host it goes through the same process as before arbitrating for the bus reselecting the host and sending an IDENTIFY message However the host s response is slightly different in this case since the disconnect was during a data transfer Host acceptance of the IDENTIFY message also implies a RESTORE DATA POINTERS message to the host The data transfer can now be resumed 8 After completion of the data transfer the target initiates a STATUS phase and sends a single status byte to the host The final action of the target is to initiate a MESSAGE IN phase and send a COMMAND COMPLETE message to the host Disconnection Notes Certain devices will disconnect on completion of a d
40. nu only one button may be selected at a time Devices which are locked are grayed out and are unable to be selected Pressing the button next to a displayed device selects that device for test Lock Target Menu This menu allows the user to lock specific devices to prevent them from being selected in the Select Device menu A good example is locking the system disk so it will not be written on inadvertently Program Text Window This area of the main application window is a non editable text window in which all program output is displayed The window is defined as an area of 24 lines of 80 characters If the font selected in the Xstb file is too large to allow the display of this much text horizontal and or vertical Scroll bars will appear Status Line This line displays various messages from the program regarding the current test status or the completion status of a test Command Line Version Syntax The command line version of the SCSI DataScrubber 13 uses the following command syntax purge SCSI target h s Where SCSI Target Defines the SCSI Target of the device to be purged Print help information S Scan the SCSI bus and display device information The command line program uses the same purg algorithm and produces the same output file as the GUI version of the program 14 Chapter Four UNIX Test Menu Quick QC Test This test will test all d
41. olled entirely by the target The target initiates the COMMAND phase and reads in the Command Descriptor Block from the host After decoding the command the target determines whether it should disconnect from the bus The target disconnects from the bus for any non trivial commands 4 The disconnect process is when the target initiates a MESSAGE IN phase and sends the host a SAVE DATA POINTERS during a DATA phase only and a DISCONNECT message Following the MESSAGE IN phase the target releases BSY freeing the bus which then enters the BUS FREE state The host can now select another target or allow another target to win the bus and reselect the host 5 Although the host and the target are physically disconnected they are still logically connected Both know that they have a command to finish and will return to that job later This principle allows many I O commands to be executed simultaneously using a single peripheral bus Once the target has completed a task and is ready to communicate with the host it must re establish the physical path The reselection process involves the target arbitrating for the bus and reselecting the host After the physical reconnection is made the target sends an IDENTIFY message to the host to indicate which target initiates the next appropriate phase for the command usually a DATA phase 40 6 Duri
42. otected Pleas be sure to honor the license agreement and only use the program on ONE COMPUTER AT A TIME If you need to purge more than one drive at a time you need to order additional copies of the program 11 Chapter Three UNIX Main Window Command Line Syntax The SCSI DataScrubber GUI main application window consists of a menu bar the Select Device menu the Lock Target menu the Program text window and the Status line Menu Bar The SCSI DataScrubber main menu bar has five menu buttons File This pull down menu has application Specific functions There are two menu selections Probe Bus Scans the SCSI bus for devices and completes the Select Device menu Quit Quits the program Options This pull down toggle button menu allows the user to turn two options on or off by pushing in or pushing out the associated buttons The options are as follows Destructive If on this allows tests to write to the device If off no write tests are allowed Log Errors If turned on all errors generated during testing will be written to a log file Commands This pull down menu provides access to the SCSI commands which are available for the selected device s Chapter 12 Tests This pull down menu provides access to the standard tests which are available for the selected devic see Chapter 5 Select Device Window This portion of the main window is a radio button me
43. pe distribution mt t tape device name rewind tar xvpf tape device name For floppy distribution tar xvpf dev fd0c Running the STB install Script The STB install script will uncompress and extract the files from the distribution format It will then prompt for necessary information as it performs the installation You will be asked into which directory you want the device driver installed into which directory you want the application files installed and asked for your authorization string The script will install the loadable device driver based on your answers to the above questions and copy the program files into the appropriate directory The Loadable Device Driver he loadable device driver is built by the install cript If you plan on having the stb device T S driver load automatically on system startup you should place the driver files in a file system which is mounted during the boot process The standard location would be a subdirectory under sys for example sys stb The script loadstb which is created in the specified device driver directory must be executed after every system boot to load the driver The SCSI DataScrubber device driver for SunOS is a loadable driver and the loadstb script may be called from the etc rc local file to load the driver on boot The device names are specified in the file makestb which is created by
44. percentage actually involve true device failure and even in these instances the power supply that powers the SCSI peripheral is often the problem source When there is a problem with the cable the symptoms vary greatly The system may not operate at all or there will be intermittent SCSI communi cation failures In many cases the symptoms are initially thought to be due to the devices on the SCSI bus or the software drivers running the devices resulting in excessive system installation delays and costs Most SCSI integrators are using some form of shielded round cables when daisy chaining external SCSI devices Shielded round SCSI cables came 44 into being because of the problems that unshielded flat ribbon cables have with electromagnetic interference EMI Unshielded cable can not pass FCC requirements whereas properly shielded round cable can function within FCC specifications However unlike poorly constructed round cabling crosstalk noise in the bus is not a problem with flat ribbon cable Crosstalk noise is best controlled in round cabling by careful conductor placement clocks in the center data around the periphery and by using twisted pair cables The combination of cabling types round versus flat and quality shielded grounded etc within a single SCSI bus can create cable impedance mismatches another common source of frustrating
45. plete This will also be a function of what type of SCSI 2 5 host adapter is being used In cases involving very large capacity disks and slow SCSI adapters it wil ll be necessary to let the purge run overnight to complete Because the progress of the purge function is monitored and tracked in the purge dat file it is not necessary for the user to intervene in the purge process 26 Chapter Six SCSI Tutorial Introduction to SCSI Philosophy The purpose of this chapter is to give an overview of SCSI SCSI encompasses hardware interfaces as well as software protocol specifications The overall goal of the SCSI specification is to free system and peripheral designers from the physical specifications of the hardware they are working with and to allow intelligence to b mbedded within peripherals This embedded intelligenc should allow the host or main processor to concentrate its power on running application code rather than mundane tasks needed to operate the peripheral The SCSI specification allows the system designer to view all peripherals as black boxes that contain blocks of data This data may be accessible randomly as in a disk drive or it may be sequentially accessible as in a tape drive or a scanner SCSI does away with dealing with heads sectors and cylinders on disk drives because SCSI only deals with logical blocks of data in the devi
46. r loaded properly This will result in an error message that says ASPI Shell Not Loaded when you try to execute the program Refer to the user manual supplied with your SCSI host adapter to correct this problem If any problems are encountered please 24 call for technical support at 303 763 7488 Example The user wishes to declassify the SCSI disk located at SCSI address 3 At the DOS command line enter purge 3 The user will be prompted to enter a serial number or other identification for the drive under test Whatever is entered here will be printed to the purge dat file on the DOS computer as a means to relate the purge report to a particular disk drive The user is then prompted to enter a block number to be used as a verification block This block will b xamined after each data pattern has been written and the data from this block will be printed to purge dat file on the DOS computer After this the purge function begins and proceeds in the following order 1 The three data patterns are written to all alternate and spare blocks on the drive 2 The three data patterns are written to all user accessible data blocks on the drive 3 The file purge dat is available to be printed Because of the process involved in accessing all alternate blocks on the drive and in writting and confirming every data block on the drive the purge function can take a long time to com
47. rive functionality over a sample block range that covers th ntire driv Positioning writing and reading are all verified by writing and verifying 1000 blocks at the beginning middle and end of the drive This is a quick quality control check to verify that the drive is indeed functioning Most operating systems pay particular attention to the first and last blocks of a disk for boot blocks label information and spare blocks for defect mapping Purge Test The Purge function provides a means to completely erase all data from a disk drive Three different data patterns are written to every block on the disk including all blocks that are used as alternate blocks and all blocks held in reserve for flaw remapping For each of the three data patterns each block on the drive has the pattern written to it then the block is read back and each byte is compared to be sure that it matches the data pattern By the time the function is complete every byte on the drive has had the following patterns written and confirmed all ones all zeros and alternating ones amp zeros A user selected block on the drive is designated as a verification block The data on the verification block is printed out after each data pattern is written to give a confirmation of what data is now stored on the drive A disk file called PURGE DAT is created that contains a record of the purge process This file contains a user
48. supplied serial number or 15 other data to identify the drive that has been purged and a journal type report of the progress of the purge The verification block data is printed to this file after each of the three data patterns is written as a confirmation that all data on the drive has been erased Operation The Purge Function is chosen from the Test menu The user is warned that this test will destroy all data on the selected drive and is asked to confirm that the function should be run Entering Y at this prompt starts the purge function The user will be prompted to enter a serial number or other identification for the drive being purged Whatever is entered here will be printed to the PURGE DAT file on the DOS computer as a means to relate the purge report to a particular disk drive The user is then prompted to enter a block number to be used as a verification block This block will b xamined after each data pattern has been written and the data from this block will be printed to the PURGE DAT file on the DOS computer After this the purge function begins and proceeds in the following order T The three data patterns are written to all alternate and spare blocks on the drive 2 The three data patterns are written to all user accessible data blocks on the drive 3x The file purge dat is available to be printed Because of the process involved in accessing all
49. th that allows higher data transfer rates and several wider data transfer paths SCSI Hardware The SCSI bus is made up of eighteen lines that carry data in the case of single ended SCSI several lines representing signal ground in the case of differential SCSI eighteen differential signal lines Thes ighteen signal lines can be thought of as two groups nine control lines and nine data lines Data Lines The data lines consist of eight bits of data and one bit of parity data The SCSI 2 specification actually allows for a wide SCSI data path of 16 or 32 bits 28 Control Lines he nine control lines consist of two lines that ontrol bus handshaking six lines that define hat state or phase the bus is in and a reset These data and control lines that make up he physical SCSI bus can use two different lectrical methods to convey information across T W line t e the bus singl nded and differential Single ended SCSI With the single ended method binary values on the SCSI bus are represented by two voltage levels on the bus lines A high level is a voltage over 2 5 volts 5 and a low level is a voltage that is less than 4 volts The single ended SCSI Specification is an active low definition That means that a logical one is represented by a low voltage level and a logical zero is represented by a high voltage level The single ended SCSI specifica
50. tion allows for a bus cable length of up to 6 meters although the maximum single ended cable length is dependent upon the number of devices on the bus speeds at which they run Single ended Termination The SCSI bus like any high speed bus must be terminated properly to prevent ringing and false signals Single ended termination consists of a resistor network on each signal line This resistor network presents a constant impedance to the SCSI bus The network consists of a 220 ohm resistor connected between 5 volts the termpower line on the SCSI bus and the signal line and a 330 ohm resistor connected between the signal line and ground It is essential to proper termination 29 that the terminating resistor network is supplied with 5 volts on the term power line Unfortunately it is a common occurrence for the device supposed to be providing term power to have blown the fuse in line with the term power line Unless you have a SCSI terminator with an LED to show that term power is valid you may never know if the proper 5 volts is being supplied to your termination Recalling that the SCSI bus is an active low bus you can see why the lack of this 5 volts can lead to very unpredictable results It is well worth using only terminators with term power indicators to avoid hours of troubleshooting headaches Differential SCSI Differential SCSI consists of a pair of signal lines for each signal The voltage
51. to copy or transfer the Software as follows a LICENSEE may transfer the Software from one computer to another of the same type and model provided that the Software is installed on only one computer at a time and covered under a current software maintenance contract b LICENSEE may transfer the Software to a computer of another type and model supported by STB after paying a service and or upgrade charge which can be quoted upon request C Copy the software for the purpose of backup or archival LICENSEE agrees to reproduce and include STB s copyright notice on all copies of the Software SOFTWARE LIMITATIONS STB does not warrant that the Software will be free from error or will meet your specific requirements You assume complete responsibility for decisions made or actions taken based on information obtained using the Software Any statements made concerning the utility of the Software are not to be construed as unexpressed or implied warranties THE LICENSEE SHALL HAVE THE SOLE RESPONSIBILITY FOR ADEQUATE PROTECTION AND BACKUP OF ITS DATA USED IN CONNECTION WITH THE LICENSED PRODUCT IN NO EVENT WILL STB CHOICE NOR ANY SUBLICENSOR BE LIABLE FOR i SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES ii ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE DATA OR PROFITS RERUN TIME INACCURATE INPUT OR WORK DELAYS OR ANY DIRECT PROPERTY DAMAGE ARISING OUT OF OR IN CONNECTION WITH THIS AGREEMENT OR THE USE OR PERFORMANCE OF THE
52. transaction happens between two SCSI devices at which time each of the devices takes on one of two roles Initiator or Target The initiator is typically the host computer and he target is typically the peripheral devic he completion of the series of transactions that nitiator and a target is called a nexus The Jr make up a full SCSI transaction between an a i ntermediate steps that happen to complete a nexus are called SCSI Bus Phases These phases ar Bus Free Phase Arbitration Phase Selection Phase Reselection Phase Information Transfer Phases which consist of Command Phase Data In Phase Data Out Phase Status Phase essage Phase The current bus phase is defined by the state of several of the control signal lines Some phases can be entered from any other phase while others must progress between phases in a specific order 31 Phase order and transition between phases is controlled by the SCSI controller chips on the host adapter and on the SCSI peripherals These chips are dedicated micro processors that control all of the timing and signal transitions necessary to assure conformance with the SCSI Specifications The Bus Free Phase The bus fr phase refers to the time when no SCSI activity is occurring on the bus No devices are selected no transfers are taking place during this phase From this phase the SCSI bus can go to the arbitration phase or in the case of a SCS
53. u will initiate the purge function A status line at the bottom of the Screen will show which drive is selected You will 23 be asked to confirm that you wish to purge this device You will then be asked to enter a serial number or ID for this device This number will appear on the purge report Finally you will be asked to specify a block number for verification This block number will be read after each data pass and the data contained in this block will be written to the purge report file As the purge progresses the screen will be updated to reflect the operation stage of the purge function At the end of the purge a file will be created on the disk from which you are operating This file is named purge dat and will contain the results of the purge operation Refer to section 4 2 for a description of this file Subsequent purge operations will append to the end of this file or you can print the file and delete it after each purge Unrecoverable Errors During the purge process the disk is reformatted and all grown defects are discarded After the format the purge program will check for any new grown defects if new grown defects are found the purge will be aborted This is to insure that if there are any physically damaged sectors which cannot be overwritten the drive is not declassified Common Problems The most common problem is not having the ASPI Software for the SCSI adapte
Download Pdf Manuals
Related Search