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      STACKER NOTE                                         STACKER NOTE
             SDEFRAG ERRORS 109/110, 120, AND 170 & STACKER 4.0
                          (Applies to Stacker 4.0)
      STAC FAX  4407 (03-28-1994)
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      BACKGROUND
      
      When SDEFRAG detects a media error on your disk, it displays an
      error message and provides brief instructions on how to correct
      the media error.  This document provides in-depth procedures for
      correcting the following SDEFRAG errors:
      
      Error Description
      109/110 170: SDEFRAG is unable to read, write, or verify a physical
      cluster on the hard disk.  This is usually caused by a media
      error.
      120: SDEFRAG is unable to decompress a physical cluster.  This
      is either caused by a media error or corrupted cluster written
      to the Stacker drive.
      
      This document is organized into two procedures.  Procedure I
      remedies SDEFRAG errors that warrant a surface scan utility.
      Complete this procedure first.  If the SDEFRAG error persists,
      then complete Procedure II. Some steps will differ, depending on
      whether you are using DOS versions that support preloading such
      as MS-DOS 6.x, Novell DOS 7, and most releases of PC-DOS 6.x, or
      if you are using other DOS versions.
      
      PROCEDURE I:  USING SURFACE SCAN UTILITIES WITH STACKER
      
      If a physical hard drive flaw (bad sector) affects the operation
      of your Stacker drive, then a disk repair utility can be used to
      detect the damaged areas and correct them.  This procedure
      explains how to use a disk repair utility to repair hard drive
      flaws in conjunction with Stacker.  Norton Utilities' Calibrate,
      PC Tools' DiskFix, and SpinRite are examples of disk surface scan
      utilities.
      
      SOLUTION
      
      To correct physical disk flaws that affect Stacker:
       - Ensure that a file attribute utility is available
       - Boot without loading device drivers
       - Unhide the STACVOL file
       - Correct the damaged, unreadable areas of your hard drive
       - Correct coincidental damage to the Stacker drive.
        
      First, locate file attribute utilities
      
      From the DOS prompt type STACKER <enter>. Locate the line that
      displays drive C. It will look something like this:
      
      Drive C was drive C at boot time [ E:\STACVOL.DSK = 173.5MB]

      The drive letter in brackets (in this case drive E) is your
      uncompressed boot drive. Go to the DOS directory on that drive
      and ensure that the DOS command ATTRIB is there. If not, copy it
      from the DOS directory on the C drive.
      
      Clean boot your system
      
      Clean boot your system using a bootable floppy diskette.  "Clean
      boot" means to start your computer without loading any device
      drivers into memory, including Stacker.  Refer to your DOS user's
      guide if you do not have a bootable floppy diskette.  Note:  if
      you use MS-DOS 6, see page 178 of the MS-DOS 6 User's Guide for
      instructions on making a Startup disk.
      
      After clean booting, your computer will display an A prompt.
      Change to the C drive and go to the DOS directory. Type:
      
           attrib -s -h -r drive:\STACVOL.* <Enter>
      where drive is the letter of the drive you are repairing.  This
      command unhides all STACVOL files on the specified drive.
      
      Run the surface scan on the physical hard drive
      
       1.  Follow the disk repair utility's instructions for running
           from a floppy disk. Use the most rigorous pattern testing
           available (typically 80-pattern) to scan the physical drive
           containing the STACVOL file, and allow it to repair
           defective areas on the disk. A rigorous surface scan may
           take several hours, depending on the size and speed of your
           hard drive.
           Note:  If you are using Norton CALIBRAT.EXE to perform
           pattern testing, it defaults to low-level formatting. IDE
           drives cannot be low-level formatted, so you must override
           low-level formatting with the following command:
                calibrat /noformat
       2.  Remove all disks from the floppy drives and restart the
           computer.
           
      Correct coincidental damage to the Stacker drive
      
       1.  Switch to the compressed drive, change to the \STACKER
           directory, and type:
              check /f <Enter>
       2.  When CHECK prompts you to perform a disk surface test,
           respond "yes."
       3.  If CHECK detects errors and prompts you to delete damaged
           files, respond "yes," then complete the on-screen
           instructions that CHECK displays.
           
      You are ready to run SDEFRAG again.  If the SDEFRAG error
      persists, then complete Procedure II.
      
      PROCEDURE II:  ENABLE DIAGNOSTIC MODE
      
      If the SDEFRAG error persists after completing Procedure I, then
      CHECK /F must be invoked in a special diagnostic mode to detect
      and correct corrupted clusters written to the Stacker drive.
      
      SOLUTION
      
      To detect and correct corrupted clusters on the Stacker drive
       - Modify your system configuration to enable diagnostic checking
       - Run CHECK /F with the surface scan option
       - Run SDEFRAG /R
       - Restore your system configuration
        
      Modify your system configuration
      
      Select the appropriate procedure to enable diagnostic checking
      and start your computer without loading any device drivers into
      memory:
      
      For Preloading versions of DOS
      
       1.  Type: ED /I <enter>. Upon entering the editor, your
           cursor will be positioned at the beginning of the first
           line.  From this position, type:
                    /R <Enter>
       2.  Press Ctrl-Z to save the file.
       3.  Reboot your computer.  When MS-DOS displays the
           following text:
                    Starting MS-DOS...
           press and release the F5 key, or press and hold down the
           SHIFT key.
      
      For other DOS versions
      
       1.  Type: ED /I <enter>. Upon entering the editor, your
           cursor will be positioned at the beginning of the first
           line.  From this position, type:
                    /R <Enter>
       2.  Press Ctrl-Z to save the file.

       3.  Type ED /C <enter> to modify the CONFIG.SYS file on
           the C drive.  Remark all device drivers and programs other
           than STACKER.COM and SWAP.COM.  The following example
           illustrates a typical CONFIG.SYS file with REM's in place:
             buffers=20
             files=30
             lastdrive=e
             REM device=c:\dos\himem.sys
             REM device=c:\dos\emm386.exe noems
             REM dos=high,umb
             REM devicehigh=c:\mouse\mouse.sys /c1
             REM devicehigh=c:\dos\smartdrv.sys 1024
             devicehigh=c:\stacker\stacker.com
             device=c:\stacker\sswap.com
           
      3.   After you have made the appropriate modifications to your
           CONFIG.SYS file, save it then restart your computer.
      
      Run CHECK /F with the surface scan option
      
       1.  Switch to the compressed drive, change to the \STACKER
           directory, and type:
              check /f <Enter>
       2.  When check prompts you to perform a disk surface test,
           respond "yes."
       3.  If CHECK detects errors and prompts you to delete damaged
           files, respond "yes." Complete the on-screen instructions
           that CHECK displays, and continue with step 4.
       4.  From the \STACKER directory, type:
              sdefrag /r <Enter>
           If the SDEFRAG error persists, then complete step 5.
           Otherwise your system is fully optimized and you can restore
           its original configuration (see next section, "Restore your
           system configuration.")
       5.  If the SDEFRAG error persists, then switch to your
           computer's slower CPU speed (i.e., press the TURBO button)
           and run SDEFRAG again.
       6.  If your computer does not have a secondary CPU speed, or if
           the SDEFRAG error persists after running SDEFRAG at the
           slower CPU speed, then do the following:
           a. Type ED /I <enter>.  Upon entering the editor, your
           cursor will be positioned at the beginning of the first
           line.  From this position, type:
                    /C=32 <ENTER>
                    /F=512 <ENTER>
           b. Press Ctrl-Z to save the file.
           c. Reboot your computer.  If you are using MS-DOS 6.x when
           it displays the following text:
                    Starting MS-DOS...
                press and release the F5 key, or press and hold down
           the SHIFT key.
       7.  After making these modifications, change to the \STACKER
           directory on your compressed drive and type:
                    sdefrag  /r  <Enter>

      Restore your system configuration
      
      After successfully optimizing your system, return it to its
      original configuration.  Repeat the editing procedure to remove
      any added switches (/R, /C=32, /F=512) from the STACKER.INI file.
      If you modified your CONFIG.SYS file, remove all the remark
      statements from the beginning of the device lines. Save the files
      and restart your system.
      
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      Copyright 1994 Stac Electronics
