UNFORMAT Does Not Work on Disk Manager Partition (71812)

The information in this article applies to:
    Microsoft MS-DOS operating system 5.0

This article was previously published under Q71812


Because MS-DOS recognizes only up to 1024 cylinders on a physical hard drive, the MS-DOS 5.0 UNFORMAT command restores only partitions at or under the 1024 cylinder limit. It does not restore a partition created using Ontrack Computer Systems' Disk Manager if that partition spans the 1024 cylinder boundary on a physical hard drive.


If a partition created using third-party partitioning software spans the 1024 cylinder boundary, it will not be restorable using the MS-DOS UNFORMAT command unless the device driver accompanying the software is first loaded. For example, it is possible to restore such a partition created using SpeedStor because its drivers, HARDRIVE.SYS or SSTOR.SYS, can be loaded whether or not a SpeedStor partition is present.

However, Disk Manager's driver, DMDRVR.BIN, does not load unless there is a Disk Manager partition detected. Because DMDRVR.BIN does not load, UNFORMAT cannot look beyond the 1024 cylinder boundary; therefore, you cannot use UNFORMAT to restore the partition.

The products included here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

Modification Type: Major Last Reviewed: 11/19/1999
Keywords: KB71812