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       STACKER NOTE                                         STACKER NOTE
                            COMPRESSING A RAM DISK
                  (Applies to Stacker 3.1 for Windows & DOS)
       STAC FAX 31406  (09/07/93)
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       BACKGROUND
       
       This document offers several strategies for compressing a ram
       disk using Stacker 3.1.  The procedures involve modifying your
       configuration files, CONFIG.SYS, STACKER.INI, and AUTOEXEC.BAT.
       Once these modifications are in place, Stacker automatically
       compresses the ram disk every time you start your computer.  See
       document 31407, "Troubleshooting Stacker Ram Disks," for more 
       information.
       
       SOLUTION
       
           Create the ram disk
           Position the ram disk
           Compress the ram disk
           Mount the compressed ram disk
            
       Create the ram disk
       
       Stacker 3.1 compression works exclusively on DOS disks with 512-
       byte sectors.  Random Access Memory (RAM) cannot be compressed,
       but a device-driven disk created from RAM is an ideal candidate
       for compression.  Stacker cannot create a ram disk, but it can
       compress one.
       
       RAMDRIVE.SYS is an example of a  ram disk utility that comes with
       MS-DOS.  This is an example of a minimal CONFIG.SYS file that
       creates a one-megabyte ram disk in extended memory using
       RAMDRIVE.SYS:
       
               device=c:\dos\himem.sys
               device=c:\dos\emm386.exe
               device=c:\dos\ramdrive.sys 1024 /e
               
       Your CONFIG.SYS file will be substantially different from this
       minimal example.  Consult your ram disk utility's user guide for
       instructions on how to create a ram disk.
       
       
       Position the ram disk
       
       When assigning drive letters, DOS processes physical hard disks
       and partitions first starting with letter "C."  Next, DOS assigns
       letters to device-driven drives like ram drives and Stacker
       drives in  the order in which they are loaded in the CONFIG.SYS
       and AUTOEXEC.BAT.
       
       For example, if you add a ram disk device driver to your
       CONFIG.SYS file  BEFORE the STACHIGH.SYS driver, then DOS
       processes the ram disk first and assigns it the next available
       drive letter.  Conversely, if you add the ram disk device driver
       AFTER the STACHIGH.SYS driver, or if the ram disk is created in
       the AUTOEXEC.BAT file, then DOS processes the Stacker drive
       letters first.
       
        1. Follow your ram disk utility's instructions for creating a
           ram disk.  If the instructions include adding commands to
           the AUTOEXEC.BAT file, ensure that they appear before the
           Stacker command:
               
               C:\STACKER\CHECK /WP
            
        2. Reboot.
        
        3. Note the startup message produced by the ram disk utility.
           It normally indicates the ram disk drive letter.
        
        4. Verify the integrity of the ram disk by running CHKDSK X:,
           where X is the ram disk drive letter.
            
       
       Compress the ram disk
       
       After you have successfully created and positioned your ram disk,
       you are ready to make the necessary configuration changes to
       compress it.  Stacker provides two utilities for compressing ram
       disks:
       
       SCREATE.SYS 
          This utility compresses ram disks from the CONFIG.SYS file.  
          Some ram disk utilities create ram disks in the AUTOEXEC.BAT
          file.  If your utility does this, then you must use CREATE
          instead.
       
       CREATE 
          This utility compresses ram disks from the AUTOEXEC.BAT file 
          and must be used if your ram disk utility completes creation 
          of ram disks in the AUTOEXEC.BAT file.
       
       
       Using SCREATE.SYS
       
       This is the syntax for compressing a ram disk in the CONFIG.SYS
       file:
       
            device=c:\stacker\screate.sys X:
       
       where X is the ram disk drive letter.
       
        1. Use a text editor to insert this command into the CONFIG.SYS
           file.  It should be the next command following your ram disk
           device driver.
       
        2. Save the file, exit the text editor, and reboot your
           computer.
            
        3. Ensure that SCREATE produces the following message when you
           reboot:
       
             SCREATE - 3.10, (C) 1991-93 Stac Electronics, Carlsbad CA
             X:\STACVOL.DSK created successfully.
       
       
       Using CREATE
       
       This is the syntax for compressing a ram disk in the AUTOEXEC.BAT
       file:
                 c:\stacker\create X: /b
       
       where X is the ram disk drive letter.
       
        1.  Use a text editor to insert this command into the
            AUTOEXEC.BAT file.  It should appear immediately before the
            Stacker check command, and after any ram disk commands:
            
               [ possible ram disk commands...]
               REM  THE CHECK LINE BELOW PROVIDES ADDITIONAL SAFETY...
               REM  PLEASE DO NOT REMOVE IT.
               c:\stacker\create X: /b
               C:\STACKER\CHECK /WP
            
        2.  Save the file, exit the text editor, and reboot your
            computer.
       
        3.  Ensure that CREATE produces the following message when you
            reboot:
       
               Stacker drive created successfully.
            
       
       Mount the compressed ram disk
       
       After you have successfully compressed your ram disk, you are
       ready to make the necessary configuration changes to
       automatically mount it.
       
       If you compressed the ram drive using SCREATE.SYS BEFORE the
       STACHIGH.SYS driver, then complete procedure 1, Mounting in
       STACKER.INI.  Otherwise complete procedure 2, Mounting in
       AUTOEXEC.BAT.
       
                          1.  MOUNTING IN STACKER.INI
       
        1.  Follow the instructions on page 15 of the Stacker 3.1
            supplement to edit the STACKER.INI file.
       
        2.  Add the following command:
       
               X:\stacvol.dsk,rp
       
            where X is the ram disk drive letter.
            
        3.  Press Ctrl-Z to save the file.

        4.  Reboot.
       
       
                         2.  MOUNTING IN AUTOEXEC.BAT
                                       
        1.  Determine if a replaceable drive is available.  From the DOS
            command prompt, type:
       
               stacker <ENTER>
       
            If the last line of the Stacker drive map indicates:
             
               No available replaceable drive(s).
       
            then complete step 1-A.  Otherwise skip to step 2.
            
       1-A. Follow the instructions on page 15 of the Stacker 3.1
            supplement to edit the STACKER.INI file.  If it already
            contains the switch:
               
               /RP=n
           
            then increase n by 1.  Otherwise, add this switch to the
            beginning of the file:
       
               /RP=2
       
            then press CTRL-Z to save the modification.
            
        2.  This is the syntax for mounting a ram disk in the
            AUTOEXEC.BAT file:
       
                 c:\stacker\stacker X:
       
            where X is the ram disk drive letter.  Use a text editor
            to insert this command into the AUTOEXEC.BAT file.  It
            should appear immediately before the Stacker check command:
       
                 [ possible ram disk commands...]
                 REM  THE CHECK LINE BELOW PROVIDES ADDITIONAL SAFETY
                 REM  PLEASE DO NOT REMOVE IT.
                 [ possible c:\stacker\create X: /b command...]
                 c:\stacker\stacker X:
                 C:\STACKER\CHECK /WP
                 .
                 .
                 .
                                       
        3.   Save the modified AUTOEXEC.BAT file.
        
        4.   Reboot.       
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       Copyright 1993, Stac Electronics                      
