Difference Between DEFRAG and DBLSPACE /DEFRAGMENT (94357)


The information in this article applies to:

  • Microsoft MS-DOS operating system 6.0
  • Microsoft MS-DOS operating system 6.2
  • Microsoft MS-DOS operating system 6.22
This article was previously published under Q94357
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.

SUMMARY

There are two ways to defragment a DoubleSpace drive: you can run DBLSPACE /DEFRAGMENT, or you can run Microsoft Defragmenter (DEFRAG.EXE).

MORE INFORMATION

Files stored on DoubleSpace drives become fragmented just as they do on physical drives.

Running DEFRAG.EXE

Microsoft Defragmenter (DEFRAG.EXE) makes files contiguous by making virtual clusters contiguous. For example, a DoubleSpace drive would change from

H:\DBLSPACE.000: [1213--542---132-2--113---4 ]
C: [1123156-1-13-5-1-2-3-1521--123------- ]

to:

H:\DBLSPACE.000: [1213--542---132-2--113---4 ]
C: [111112222333344455556---------------- ]

NOTE: In this example, each number represents a piece of a file. For example, each "1" indicates a piece of file 1.

Running DBLSPACE /DEFRAGMENT

DBLSPACE /DEFRAGMENT moves data within the compressed volume file (CVF) so that all the free space is at the end. Files aren't made contiguous; they are simply placed in one group at the front of the drive. Using the same example, the file would change from

H:\DBLSPACE.000: [1213--542---132-2--113---4 ]
C: [1123156-1-13-5-1-2-3-1521--123------- ]

to:

H:\DBLSPACE.000: [121354213221134----------- ]
C: [1123156-1-13-5-1-2-3-1521--123------- ]

Running DBLSPACE /DEFRAGMENT /F

DBLSPACE/DEFRAG/F moves all the used sectors to the end of the CVF. Using the same example, the file would change from

H:\DBLSPACE.000: [1213--542---132-2--113---4 ] C: [1123156-1-13-5-1-2-3-1521--123------- ]

to:

H:\DBLSPACE.000: [-----------121354213221134 ]
C: [1123156-1-13-5-1-2-3-1521--123------- ]

NOTE: When you run DBLSPACE with the /DEFRAGMENT parameter, it may not make all of the unused sectors contiguous; this is why the /F switch exists. If you cannot resize a DoubleSpace drive because it is too fragmented, you must defragment the drive with DBLSPACE /DEFRAGMENT and then with Defragmeter.

To do this:

  1. Run DBLSPACE to defragment the CVF.
  2. Move all the sectors to the end of the disk by typing the following at the MS-DOS command prompt:

    dblspace /defragment /f

  3. Run Defragmenter with the /F parameter by typing the following at the MS-DOS command prompt:

    defrag /f

    This should move all of the data to the end of the CVF and then back to the front. All of the unused sectors should then be contiguous.

Fully Optimizing Your DoubleSpace Drive

If you type DEFRAG to defragment a DoubleSpace drive, Defragmenter runs DBLSPACE /DEFRAGMENT when it has completed. Once both types of defragmentation have been done, the sample file appears similar to the following:

H:\DBLSPACE.000: [121354213221134----------- ]
C: [111112222333344455556---------------- ]

Note that files are contiguous on the virtual drive (drive C) but not within the CVF. Free space is contiguous in both places.
Modification Type:MajorLast Reviewed:11/16/1999
Keywords:KB94357
©2002 Microsoft Corporation. All rights reserved.