	 _________________________________________________________________
	 STACKER NOTE                                         STACKER NOTE
			   SDEFRAG ERRORS 109/110, 120, AND 170
			 (Applies to Stacker Versions 3.0, 3.1 & 4.0)
	 STAC FAX 3405  (09/07/93)
	 _________________________________________________________________
	 
	 
	 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   |      SDEFRAG is unable to read, write, or verify a |
	 |            |      physical cluster on the hard disk.  This is   |
	 |    170     |      usually caused by a media error.              |
	 |------------+----------------------------------------------------|
	 |            |      SDEFRAG is unable to decompress a physical    |
	 |    120     |      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.
	 
	 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 scan and 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
	 This step is not necessary if you are using Stacker 3.1 and MS-
	 DOS 6.0.  Otherwise, copy two files, SATTRIB.* and SDIR.*, to the
	 \STACKER directory on the uncompressed boot 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, the correct procedure is entitled "Making a
	 Startup Disk" on page 178 of the MS-DOS 6 User's Guide.
	 
	 After clean booting, your computer will display an A prompt.
	 Select the appropriate procedure to unhide the STACVOL file:
	 
	 For MS-DOS 6
	 +-----------------------------------------------------------------+
	 |From the A: command prompt, 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.        |
	 +-----------------------------------------------------------------+

	 For DOS Versions other than MS-DOS 6.0
	 +-----------------------------------------------------------------+
	 |Switch to drive C:, change directory to \STACKER, and type:      |
	 |                                                                 |
	 |        sdir drive:\STACVOL.* /h <ENTER>                         |
	 |                                                                 |
	 |where drive is the letter of the drive you are repairing.  This  |
	 |command lists STACVOL file(s) which you must unhide individually.|
	 |Consider the following sample SDIR output which lists two STACVOL|
	 |files:                                                           |
	 |                                                                 |
	 |        Directory of  C:\                                        |
	 |        STACVOL  000 27182080   6-3-93  7:22p  HIDDEN            |
	 |        STACVOL  DSK 31415296   6-3-93  7:22p  HIDDEN            |
	 |        2 File(s)  1048576 bytes free                            |
	 |                                                                 |
	 |The following commands, typed at the command prompt, unhide both |
	 |files:                                                           |
	 |                                                                 |
	 |        sattrib -s -h -r C:\STACVOL.000 <ENTER>                  |
	 |        sattrib -s -h -r C:\STACVOL.DSK <ENTER>                  |
	 |                                                                 |
	 |Repeat this command for each STACVOL file in your SDIR listing.  |
	 +-----------------------------------------------------------------+
	 
	 Run the surface scan on the physical hard drive
	 
	 1.  Follow the disk repair utility's instructions for running
	     from floppy.  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 diskettes 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 Stacker 3.1
	 +-----------------------------------------------------------------+
	 |1. For Stacker 3.1, follow the instructions on page 15 of the    |
	 |   Stacker 3.1 supplement to edit the STACKER.INI file.  For     |
	 |   Stacker 4.0, from the DOS prompt 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=0 <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 Stacker Versions prior to 3.1
	 +-----------------------------------------------------------------+
	 |1. Insert the bootable floppy diskette used in Procedure I,      |
	 |   "Clean boot your system," into drive A.  Switch to the root   |
	 |   directory of drive C, and copy the file CONFIG.SYS to the     |
	 |   floppy:                                                       |
	 |                                                                 |
	 |             copy config.sys a: <ENTER>                          |
	 |                                                                 |
	 |2. Use a text editor to modify the CONFIG.SYS file on the A      |
	 |   drive.  Remark all device drivers and programs other than     |
	 |   STACKER.COM and SSWAP.COM.  Add the /R=0 switch to the end    |
	 |   of the STACKER.COM statement.  The following example          |
	 |   illustrates a typical CONFIG.SYS file with modifications:     |
	 |                                                                 |
	 |      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 c:\stacvol.dsk /R=0      |
	 |      device=c:\stacker\sswap.com c:\stacvol.dsk /sync+          |
	 |                                                                 |
	 |3. After you have made the appropriate modifications to your     |
	 |   CONFIG.SYS file, save it to the A drive, 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
	     error persists after running SDEFRAG at the slower CPU speed, 
	     then select the appropriate procedure to reduce the amount of 
	     memory available to SDEFRAG:

	 For Stacker 3.1
	 +-----------------------------------------------------------------+
	 |1. Repeat the STACKER.INI editing procedure.  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>                                      |
	 |                                                                 |
	 |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 Stacker Versions prior to 3.1
	 +-----------------------------------------------------------------+
	 |1. Use a text editor to modify the CONFIG.SYS file on the A      |
	 |   drive.  Add the switches /C=32 and /F=512 to the end of the   |
	 |   STACKER.COM statement.  For example:                          | 
	 |                                                                 |
	 |   device=c:\stacker\stacker.com c:\stacvol.dsk /R=0 /C=32 /F=512|
	 |                                                                 |
	 |2. Save the CONFIG.SYS file to the A drive, then restart your    |
	 |   computer.                                                     |
	 +-----------------------------------------------------------------+


	 7.  After reducing the amount of memory available to SDEFRAG, change
	   to the \STACKER directory on your compressed drive and type:

		sdefrag /r <Enter>


	 Restore your system configuration
	 
	 If you use Stacker 3.1 with MS-DOS 6.0, then repeat the editing
	 procedure to remove the /R=0 switch from the STACKER.INI file, and
	 restart your computer.  For versions of Stacker prior to 3.1,
	 remove the bootable floppy diskette from drive A and restart your
	 computer.
	 _________________________________________________________________
	 Copyright 1993, Stac Electronics
