DoubleSpace, Drive Letters, and Installable Devices (97885)


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 Q97885

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.

This article discusses how MS-DOS DoubleSpace assigns drive letters when installable block device drivers are loaded in the CONFIG.SYS file. Drive assignments depend on the order of device drivers in relation to the DEVICEHIGH=C:\DOS\DBLSPACE.SYS /MOVE command in the CONFIG.SYS file.

NOTE: Installable block device drivers (for example, RAMDRIVE.SYS) affect DoubleSpace because they use drive letters.

MORE INFORMATION

If no block devices appear before the DBLSPACE.SYS command in the CONFIG.SYS file, host drive letters are assigned according to the ActivateDrive line in DBLSPACE.INI file on the host drive. Any unused letters between the FirstDrive and LastDrive lines appear as "Available for DoubleSpace" when you type dblspace /list at the MS-DOS command prompt. For example, if you have the following configuration files: 
   CONFIG.SYS:           DBLSPACE.INI
   -----------           ------------
   DBLSPACE.SYS          LastDrive=H
   RAMDRIVE.SYS          ActivateDrive=H,CO
your DBLSPACE /LIST would look something like this: 
   Drive  Type
   -----  -------------------------
     A    Removable-media drive
     B    Removable-media drive
     C    Compressed hard drive
     D    Available for DoubleSpace
     E    Available for DoubleSpace
     F    Available for DoubleSpace
     G    Available for DoubleSpace
     H    Local hard drive
     I    RamDrive
However, if a block devices loads before DBLSPACE.SYS in the CONFIG.SYS file, it uses the first drive letter available after the last physical drive before any Double Space drives mount. As a result, if a drive letter taken by a block device would otherwise have been either a host drive or an "Available for DoubleSpace" drive, DoubleSpace moves the host or "Available..." drive to a different letter. The letter used is one greater than the LastDrive specified in the DBLSPACE.INI. For example, if you have the following configuration files: 
   CONFIG.SYS:           DBLSPACE.INI
   ------------          ------------
   RAMDRIVE.SYS          LastDrive=H
   DBLSPACE.SYS          ActivateDrive=H,C0
your DBLSPACE /LIST would look something like this: 
   Drive  Type
   -----  -------------------------
     A    Removable-media drive
     B    Removable-media drive
     C    Compressed hard drive
     D    RamDrive
     E    Available for DoubleSpace
     F    Available for DoubleSpace
     G    Available for DoubleSpace
     H    Local hard drive
     I    Available for DoubleSpace
If more than one block device is loaded prior to the DBLSPACE.SYS command in the CONFIG.SYS file, each block device causes DoubleSpace to move a host or "Available" drive, using successive letters after the LastDrive.

This results in DoubleSpace reserving drive letters after the drive letter specified by the LastDrive line in the DBLSPACE.INI file.

For example, if you have a Novell network in the case above, Novell would use drive letters starting after those reserved by DoubleSpace, regardless of the LastDrive line in the DBLSPACE.INI file. However, if letter specified by the LastDrive line in the CONFIG.SYS file is greater than the last drive letter reserved by DoubleSpace, Novell NetWare uses drive letters starting after the letter in the LastDrive line in the CONFIG.SYS file.
Modification Type: Major Last Reviewed: 12/3/1999
Keywords: KB97885
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