Attempting to Create a Permanent Swap File (PSF) on a Compressed Drive
To work around this situation, delete the PSF and create a PSF on your
The host drive is the drive that actually contains the DoubleSpace
compressed volume file (CVF). To determine which drive is your host
drive, type dblspace /list
MS-DOS command prompt and then press ENTER. Any drive listed as a
"Local hard drive" is valid for a PSF.
When you create a new PSF on the host drive, you may receive the
Windows will not use more than the virtual memory specified by the
Recommended Size. Are you sure you want to create a larger
As long as the PSF is not larger than four times your physical memory,
Windows can use a swap file that is larger than the Recommended Size.
Receiving the Error "Corrupt Swap File Warning" After Installing DoubleSpace
If you receive the "Corrupt Swapfile Warning" error message after
installing DoubleSpace, it is likely that your SYSTEM.INI file was not
changed to reflect the PSF drive letter change.
NOTE: In some cases, you do not receive this error; instead, the
machine stops responding (hangs) when you start Windows.
To work around this problem, refer to the section in this article
titled "Attempting to Create a Permanent Swap File (PSF) on a
If you cannot run Windows because it hangs, do the following:
• Use MS-DOS Editor to edit the [386Enh] section of the SYSTEM.INI
file and set Paging=NO.
• Save the SYSTEM.INI file and quit MS-DOS Editor.
• Run Windows, then and refer to the section in this article titled
"Attempting to Create a Permanent Swap File (PSF) on a Compressed
Receiving the "Unsupported DOS Version" Error Message
When you run Windows 3.0 in real mode (in order to run SWAPFILE.EXE),
you receive the following message:
Unsupported DOS version; upgrade to DOS version 3.1 or higher
This message is occurs when you have a corrupted permanent swap file (PSF)
or you just installed MS-DOS.
If you have SPATCH.BAT from MS-DOS 6.2 or the MS-DOS 6 Supplemental Disk,
you can work around this problem by running SPATCH.BAT (regardless of which
version of Windows you have). To do so, type the following at the command
For <drive> and <path>, specify the location of your Windows directory. For
example, if your Windows directory is on drive C and is named WINDOWS, you
would type the following:
If you have SPATCH.BAT included with MS-DOS 6.0 and Windows 3.0, you must
use the version of SPATCH.BAT available on the MS-DOS 6 Supplemental Disk
or upgrade to MS-DOS 6.2. As an alternative, you can modify the SPATCH.BAT
file provided with the MS-DOS 6 Upgrade by using an ASCII text editor, such
as MS-DOS Editor, to change the SET ADDR= line in SPATCH.BAT from "SET
ADDR=2df2" to "SET ADDR=2dc0" (without the quotation marks). To use the
MS-DOS 6.0 version of SPATCH.BAT, use the following syntax:
For <drive> and <path>, specify the location of your SWAPFILE.EXE file. For
example, if your SWAPFILE.EXE file is on drive C in the WINDOWS\SYSTEM
directory, you would type the following:
NOTE: The version of SPATCH.BAT on the MS-DOS 6 Supplemental Disk and the
version included with MS-DOS 6.2 work on both the Windows 3.0 and Windows
3.0a SWAPFILE.EXE files.
If you have Windows 3.0 (not 3.0a) and you run the version of SPATCH.BAT
provided with MS-DOS 6 Upgrade, your SWAPFILE.EXE file will be corrupted.
You can restore this file by copying the SWAPFILE.SAV file as SWAPFILE.EXE
to your Windows directory. The SWAPFILE.SAV file is not always easy to find
because it is placed in the directory from which you ran SPATCH.BAT. For
example, if you ran SPATCH.BAT from the root directory of your C drive, use
the following command to restore your PSF:
copy c:\swapfile.sav c:\windows\swapfile.exe
To obtain the MS-DOS 6 Supplemental Disk, use the order form in the back of
the "User's Guide."
Why You Cannot Have a PSF on a Compressed Drive
Windows accesses a PSF directly through the disk controller if the
32-Bit Disk Access (FastDisk) option is selected. If this option is
not selected, Windows uses the BIOS to access the PSF. Both these
methods access your hard disk at a level that is below compressed
drives. This causes Windows to read invalid data and issue the
"Corrupt Swap File Warning" message.
Why Windows Doesn't Detect DoubleSpace
Windows cannot create a PSF on a compressed volume file (CVF) created
by a disk-compression program (such as DoubleSpace, Stacker, and
SuperStor). Since Windows performs directdisk read/write operations
to a PSF, the swap file must be located on a physical hard disk, not a
NOTE: Because DoubleSpace had not been developed when Windows 3.1 was
released, it was not possible to add detection code to Windows to
prevent it from installing on a DoubleSpace drive.
TROUBLESHOOTING Potential Problems with the Workaround
If there is not enough disk space on an uncompressed drive for a swap
file, you must either delete files from the host drive or reduce the
size of the compressed drive.
For example, if your compressed drive is C and your host drive is H,
you could use the following command to decrease the size of the
compressed drive, creating 12 megabytes (MB) of free space on the host
dblspace /size /reserve=12 c:
If you receive the error message "Drive C is too fragmented to
resize," type defrag /h /q c:
MS-DOS command prompt and then press ENTER.
For more information on DoubleSpace, do the following:
• Type help dblspace at the MS-DOS
command prompt and then press ENTER.
• Type dblspace at the MS-DOS command
prompt, press ENTER, then choose Contents from the Help menu.