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      STACKER NOTE                                         STACKER NOTE
                          BACKING UP STACKER DRIVES
                  (Applies to Stacker for OS/2 & DOS ver 4)
      STAC FAX  64401 (1/95)
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      BACKGROUND
      
      Backing up a Stacker drive is no different than backing up any
      other drive. You can use your backup software as you normally
      would. Keep in mind that you must use OS/2 backup software
      to back up an OS/2 drive. Otherwise you can damage the extended
      attribute information that OS/2 maintains.
      
      Will the backed up files be in compressed or uncompressed form?
      
      Stacker decompresses files as they are read from the hard drive
      then hands them to the backup software in their original,
      uncompressed state. If the backup software uses compression, it
      will recompress the files before storing them to disk or tape.
      This means that the files can be restored to any drive,
      compressed or not.
      
      Is there anything else to be aware of when backing up data
      compressed by Stacker?
      
      There are a few extra matters to keep in mind when backing up a
      system which has Stacker installed. When it compresses data on a
      boot drive, Stacker keeps files needed to start the system on the
      uncompressed drive. Use the following procedure as a guideline to
      determine the compressed or uncompressed drive and what should be
      backed up on each drive.
      
      PROCEDURE
      
       1.  Determine which is the compressed drive and which is the
           uncompressed drive that swaps with the Stacker drive. Use
           Stacker's SWAPMAP utility.
           a. Get to a DOS command line, either DOS full screen or DOS
           window (open the Command Prompts folder and then double-
           click a DOS command prompt icon).
           b. At the DOS prompt, type:
           d:\STACKER\SWAPMAP <Enter>
           where d is the drive that contains the Stacker files. For
           example, if you installed the Stacker files on drive C, you
           would type:
           C:\STACKER\SWAPMAP <Enter>
       
           The output should look something like:
           SWAPMAP - 1.00, (c) 1993, Stac Electronics, Carlsbad, CA
           Drive A: was drive A: at boot time
           Drive B: was drive B: at boot time
           Drive C: was drive D at boot time [ D:\STACVOL.DSK = xx.xMB
           (physical) ]
           Drive D: was drive C at boot time
           The output in the above example shows that drive C is the
           Stacker drive, and drive D is the uncompressed drive.
       2.  Back up drive C as you normally would.
       3.  Back up drive D but do not back up the hidden file
           STACVOL.DSK. That file holds all the compressed information
           that makes up drive C.
           
      How do I restore my system in the event of a hard disk crash?
      
      Depending on the severity of the crash, you may need to reinstall
      OS/2. Then, restore the uncompressed drive files from backup.
      Edit the CONFIG.SYS file on your OS/2 boot drive to remove the
      Stacker device driver commands. (They will be added when you
      reinstall Stacker.) The next step is to install Stacker to create
      the compressed drive(s). The final step is to restore the files
      from backup to the Stacker drive(s).
      
      How do I read the Stacker Toolbox Backup Status Gauge?
      
      The Backup Status Gauge displays the percent of your drive that
      is not backed up. This report is based on the percentage of disk
      space (not number of files) not backed up. The Gauge takes into
      account both the number and size of files when displaying its
      report.
      
      The Backup Status Gauge examines the files on your drive for the
      archive bit. The archive bit is a attribute that is "set" on each
      file whenever it is created or modified. Most backup programs
      "clear" this attribute whenever they back up a file. The backup
      programs can use the archive attribute to keep track of files
      that have changed since the last back up. In the same way, the
      Backup Status Gauge can report the same files by telling you what
      percent of your files have the archive bit set. See your
      operating system documentation for further information on the
      archive attribute.
      
                                    Note
       Not all backup methods clear the archive attribute. If you use
      such a method, the Backup Status Gauge will not show your disk's
                                true status.
      
      
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      Copyright 1995 Stac Electronics
