_________________________________________________________________ STACKER NOTE STACKER NOTE COMPRESSING A RAM DISK (Applies to Stacker 3.1 for Windows & DOS) STAC FAX 31406 (09/07/93) _________________________________________________________________ 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 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. _________________________________________________________________ Copyright 1993, Stac Electronics