Knowledge Base

ScanDisk Marks Valid Clusters Bad with Incorrect CMOS Settings

Article ID: 119429

Article Last Modified on 11/20/1999

Microsoft MS-DOS 6.2 Standard Edition
Microsoft MS-DOS 6.21 Standard Edition
Microsoft MS-DOS 6.22 Standard Edition

This article was previously published under Q119429

SYMPTOMS

When you perform a surface scan with ScanDisk, some valid, usable clusters are designated as bad (unusable).

CAUSE

This problem occurs if your CMOS settings are set incorrectly for your hard disk drive. For example, if you have a 150-megabyte (MB) hard disk and the CMOS is set for a 20-MB hard disk, ScanDisk scans the first 20 MB correctly, but the remaining 130 MB are mark as bad.

RESOLUTION

To correct your cluster entries:

Back up your files.
Correct your CMOS settings. (For more information, contact your hardware vendor.)
Run FORMAT /C /S to reformat the drive. (The /C parameter tells FORMAT to reexamine each cluster, and the /S parameter makes the drive bootable.)

NOTE: Use the /S parameter only if the hard disk is your C drive.
Reinstall MS-DOS and Microsoft Backup.
Restore your data.

MORE INFORMATION

Running ScanDisk after you correct the CMOS settings does not correct the problem. To avoid corrupting protection schemes that mark clusters bad, ScanDisk does not change usable clusters marked as bad back to good.

Additional query words: 6.20 6.21 6.22 unused

Keywords: KB119429