Setup Reports Less Free Space than MS-DOS (DoubleSpace Drive) (103527)

The information in this article applies to:
    Microsoft MS-DOS operating system 6.2
    Microsoft MS-DOS operating system 6.22

This article was previously published under Q103527


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.


You are running Microsoft MS-DOS 6.2 DoubleSpace, drive C is compressed, and you receive the following message when attempting to install MS-DOS 6.2 Upgrade or Step-Up:

There is not enough free space on drive C to install MS-DOS. You cannot install MS-DOS unless your computer has at least 4,200,000 bytes of free disk space on drive C. Exit Setup, and move or delete unneeded files from the drive. For more information about freeing disk space, see 'Diagnosing and Solving Problems.'

Press ENTER to exit Setup.


MS-DOS 6.2 Setup may display this error message if the DoubleSpace compressed volume file (CVF) does not contain a minimum of 4,200,000 bytes of free contiguous hard disk space (even though sufficient hard disk space is reported by CHKDSK or DIR).


To work around this problem, defragment the DoubleSpace-compressed drive using the DoubleSpace Defrag utility. For example, type dblspace /defrag at the MS-DOS command prompt and then press ENTER.

DoubleSpace Defrag optimizes the DoubleSpace CVF and creates a contiguous block of free space in the CVF. You should then be able to successfully run the MS-DOS 6.2 Setup program.

If Setup still reports there is insufficient space, free some space by moving or deleting files from the drive.

IMPORTANT: If you are installing MS-DOS 6.2 Step-Up, do not delete MS-DOS files from your hard disk to free space. Step-Up requires these files to update your system.


MS-DOS 6.2 Setup uses a new DoubleSpace application program interface (API) function when you install over MS-DOS 6.2. The new API call provides Setup with the amount of contiguous free space in the compressed volume file's "sector heap" (data area).

Modification Type: Major Last Reviewed: 11/21/1999
Keywords: KB103527