Convert Drive to DriveSpace in MS-DOS 6.22

This article explains how to convert an existing uncompressed hard drive or floppy disk into a compressed DriveSpace format using MS-DOS 6.22. It details the precise command-line structure, the function of each required and optional parameter, and how the operating system handles the conversion process to maximize available storage space without losing existing files.

The DRVSPACE /COMPRESS Command

In MS-DOS 6.22, converting an existing drive to the DriveSpace compressed format is performed using the DRVSPACE /COMPRESS command. The standard command structure is:

DRVSPACE /COMPRESS drive1: [/NEWDRIVE=drive2:] [/RESERVE=size]

Parameter Breakdown

  • drive1:
    This required parameter specifies the letter of the existing drive you want to compress (for example, C: or D:).

  • /NEWDRIVE=drive2:
    This optional parameter sets the drive letter for the newly created "host" drive. When DriveSpace compresses an existing drive, the original drive letter (e.g., C:) represents the compressed volume where your files are stored, while the physical hardware receives a new drive letter (such as H:) to host the hidden Compressed Volume File (CVF). If omitted, DriveSpace automatically assigns the next available drive letter.

  • /RESERVE=size
    This optional parameter specifies the amount of free space, measured in megabytes, to leave uncompressed on the host drive. Leaving space uncompressed is useful for files that cannot be stored on a compressed drive, such as the Windows permanent swap file.

Example Usage

To compress an existing C: drive, assign drive letter H: to the uncompressed host drive, and reserve 10 MB of uncompressed space, run:

DRVSPACE /COMPRESS C: /NEWDRIVE=H: /RESERVE=10

To compress a secondary partition or floppy disk with default settings:

DRVSPACE /COMPRESS D:

Conversion Process

Executing the command initiates an automated multi-step sequence:

  1. Integrity Check: MS-DOS runs SCANDISK to ensure the target drive has no bad clusters or file system errors.
  2. Defragmentation: The drive is defragmented to consolidate free space.
  3. Volume Creation: DriveSpace creates the hidden CVF (named DRVSPACE.000) and compresses existing files into it.
  4. System Restart: The system updates DRVSPACE.INI and reboots to load the compressed volume with the original drive letter.

Alternatively, running DRVSPACE without any command-line parameters launches the full-screen menu interface, allowing you to select Compress from the menu bar and choose an existing drive to convert interactively.