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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  4407fix (09-16-1994)
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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 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.
      
      SOLUTION
      
          - Repair errors on the drive reported by the Optimizer.
          - Using surface scan utilities with stacker.
           
      Repair errors on the drive reported by the Optimizer
      
      If you receive any of the above errors, you will be instructed to
      look at the STACKER.LOG file for that drive for futher
      information.
      
       1.  Determine the uncompressed drive associated with the Stacker
           drive where you received the error. Go to a DOS prompt and
           type STACKER <enter>. Locate the line that displays the
           drive where you received the error. It will look something
           like this:
           Drive C was drive C at boot time [ E:\STACVOL.DSK = 123.4MB]
           The drive letter in brackets (in this case drive E) is your
           uncompressed drive.
       2.  Go to the root directory on that drive and type ED
           drive:\STACKER.LOG <enter>, where drive: is the drive letter
           you noted above. This will bring up the STACKER.LOG in an
           editor. Examine the file for error messages associated with
           the optimizer.
       3.  If the message tells you to run a surface scan on the
           physical drive, follow the procedures below. If the message
           tells you that you have files with errors, copy the files to
           another drive or diskette, and then delete them from the
           Stacker drive.
           
      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.
      
      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 = 123.4MB]
      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" means to start your computer without loading any
      device drivers into memory, including Stacker.  If you are using
      DOS 6 or greater, restart your system. As soon as you see the
      message "Starting xx-DOS...", press and hold the Ctrl-Alt-Shift
      keys. When prompted, press ESC to abort the installation of
      Stacker. If you have an earlier version of DOS, start your system
      from a bootable floppy disk. See your DOS documentation for
      making a bootable disk if you do not already have one.
      
      Unhide the STACVOL file
      
      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.
           
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      Copyright 1994 Stac Electronics
