Q96200: DoubleSpace Cannot Mount Compressed Write-Protected Disk

Article: Q96200
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:6.0,6.2; WINDOWS:95
Operating System(s): 
Keyword(s): kbenv kbtool msdos
Last Modified: 17-DEC-2000

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

- Microsoft MS-DOS operating system versions 6.0, 6.2 
- Microsoft Windows 95 
-------------------------------------------------------------------------------

SYMPTOMS
========

When you try to mount a write-protected disk with DoubleSpace, you receive the
following error message:

  DoubleSpace cannot mount drive <x> because the file
  <x>:\DBLSPACE.nnn is not a valid compressed volume file.

where <x> is the floppy disk drive letter.

When you try to mount a write-protected removable media disk under MS-DOS 6.2,
you receive the following error:

  Dblspace cannot mount drive <drive letter>:
  The <drive letter>:\Dblspace.000 file is not a valid compressed
  volume file. To fix it, type scandisk X:\Dblspace.000 at the
  command prompt.

WORKAROUND
==========

To work around this problem, remove the write protection for the disk.

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

When DoubleSpace mounts a compressed volume file (CVF), it ensures the Microsoft
DoubleSpace BIOS parameter block (MDBPB) (the overall configuration sector) and
the BitFAT (a table of available heap sectors) are current. To do this,
DoubleSpace must write to the disk. This feature is under review and will be
considered for inclusion in a future release.

You can mount a floppy disk by running DoubleSpace, or you can mount the floppy
disk with the MS-DOS DBLSPACE /MOUNT command. For example, type the following
command at the MS-DOS command prompt and press ENTER if your floppy disk drive
is drive A:

  "dblspace /mount a:" (without the quotation marks)

For more information on DoubleSpace, type "help dblspace" (without the quotation
marks) at the MS-DOS command prompt and press ENTER.

STATUS
======

This behavior is by design.

Additional query words: 6.00 6.20 win95 win95x read-only read only drivespace drvspace

======================================================================
Keywords          : kbenv kbtool msdos 
Technology        : kbWin95search kbZNotKeyword3 kbMSDOSSearch kbMSDOS620 kbMSDOS600
Version           : MS-DOS:6.0,6.2; WINDOWS:95

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

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.

Copyright Microsoft Corporation 1986-2002.