KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q95633: Automating RAMDrive Compression with DoubleSpace

Article: Q95633
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:6.0,6.2,6.21,6.22
Operating System(s): 
Keyword(s): 
Last Modified: 19-NOV-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft MS-DOS operating system versions 6.0, 6.2, 6.21, 6.22 
-------------------------------------------------------------------------------

SUMMARY
=======

This information applies to both Microsoft DoubleSpace and Microsoft DriveSpace.
For MS-DOS 6.22, use DRVSPACE in place of DBLSPACE for commands and filenames.

It is possible to compress a RAM drive with DoubleSpace. However, since the
information on the RAM drive is lost each time you restart your computer, you
must recompress the RAM drive each time you start your system.

You can avoid this problem by storing the RAM drive compressed volume file (CVF)
on your hard disk drive and placing two commands in your AUTOEXEC.BAT file to
copy and mount the CVF on the RAM drive when you start your computer.

MORE INFORMATION
================

You can automate the compression of the RAM drive with the following procedure:

1. Create RAM drive. For example, to create a 1-megabyte (MB) RAM drive in
  extended memory, place the following statement in your CONFIG.SYS file:

     device=c:\dos\ramdrive.sys 1280 /e

2. Restart your computer to load the RAM drive.

  NOTE: MS-DOS assigns the next available drive letter for the RAM drive. For
  example, if you only have one hard disk drive (C), the RAM drive is assigned
  the drive letter D. This procedure uses drive D as the RAM drive.

3. Compress the RAM drive. For example, to compress drive D, type the following
  at the MS-DOS command prompt and the press ENTER:

  " dblspace /compress d: " (without the quotation marks)

4. Resize the compressed drive to its maximum size (and thereby reduce the size
  of the host drive to zero bytes). For example, type the following at the
  MS-DOS command prompt and then press ENTER:

  " dblspace /size /reserve=0 d: " (without the quotation marks)

5. Change the CVF attributes so the file can be copied. For example:

     attrib h:\dblspace.000 -s -h -r

  This example assumes the host drive is drive H. To determine your host drive,
  type "dblspace /list" (without the quotation marks) at the MS-DOS command
  prompt. Write the drive mapping information down, because you need it in step
  5.

6. Copy the compressed volume file (CVF) to your hard disk drive.

  To avoid having to recompress the RAM drive each time you start your computer,
  you must store the CVF on your hard disk drive. This requires approximately 1
  MB of space.

  To copy the compressed volume file to your hard drive, type the following at
  the MS-DOS command prompt:

  " copy h:\dblspace.000 c:\dos\ramcvf.000 " (without the quotation marks)

  Since this file cannot be compressed (it already is), you should copy it to an
  uncompressed drive.

7. Add the following lines to your AUTOEXEC.BAT file so that the CVF is copied
  to your RAM drive and mounted each time you start your computer.

  " REM Copies and Mounts CVF to RAM drive
  copy c:\dos\ramcvf.000 d:\dblspace.000
  dblspace /mount=000 d: /newdrive=h: " (without the quotation marks)

  Substitute the appropriate drive letters for C, D, and H. Drive C should be
  the uncompressed drive on which you store the RAM drive CVF; drive D is the
  RAM drive, and drive H is the host drive.

8. Restart your computer. To determine if the procedure worked, type "dblspace
  /list" (without the quotation marks) at the MS-DOS command prompt and press
  ENTER.

WARNING: Any information stored on a RAM drive is lost when you restart or turn
off your computer. To prevent data loss, copy any file you want to save from
your RAM drive to your hard disk drive before turning off your computer.

NOTE: Since DoubleSpace uses a 512-byte sector size, RAM drives must be created
with a 512-byte sector size so that DoubleSpace can compress the drive. If a RAM
drive is created with a sector size of 128 bytes or 256 bytes, DoubleSpace does
not recognize the drive as available for compression. The default value for the
sector size of a RAM drive created with RAMDRIVE.SYS included with MS-DOS 6.0 is
512 bytes. For information on changing the sector size of a RAM drive, type the
following at the MS-DOS command prompt and press ENTER:

  " help ramdrive.sys " (without the quotation marks)

Additional query words: 6.0 6.20 6.21 6.22 compressed double space dblspace ram drive

======================================================================
Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600
Version           : MS-DOS:6.0,6.2,6.21,6.22

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.