NewDeal Technical Support Document 248
DAMAGED HARD DRIVE
Occasionally any hard disk can develop minor surface defects which can
cause problems with your data. If your programs suddenly start giving you
error messages, or crashing without error messages, and you haven't
changed your computer's configuration, you might have damaged sectors. The
bad sectors are usually easy to find and fix.
How to check your hard drive for bad sectors, and how to
Damaged sectors are sometimes called "check disk errors,"
named so after the DOS program CHKDSK, which can sometimes be used to
Commercial Hard Disk Utility Programs
The best way to find and fix bad sectors is to use a commercial hard disk
utility program, such as Norton Disk Doctor, PC Tools' Disk Fix, or
Microsoft's ScanDisk. There are many other products available for the
same purpose. If you use a commercial hard disk repair program, follow
the instructions in the program's manual for finding and repairing the
damage. Then go to "The Final Step" section below.
Finding Damaged Files using CHKDSK
If you don't own a hard disk utility program, you can use the DOS command
CHKDSK to find and repair some file errors. However, keep in mind that
commercial disk checking programs have a higher success rate for finding
and repairing damaged files. Also, be aware that CHKDSK cannot find or
repair physical defects on the disk, CHKDSK can only locate problems with
the file directory structure.
To check for damaged files with CHKDSK, exit any programs you have
running. At any DOS prompt, enter
If CHKDSK finds errors, it will report them with a message
like "Errors found" or "Cross-linked files."
If CHKDSK prompts you to "Convert lost chains to files?"
enter Y. DOS will convert the information stored in the damaged files
into files with the file name extension CHK. You can delete these files later
if you don't want to try to recover information from them.
Fixing Cross-Linked Files
CHKDSK cannot fix files that are cross-linked. To fix them, you must
delete every file that DOS reports as being cross-linked. After you
delete the files, run CHKDSK /f again.
If CHKDSK Didn't Find Any Problems
CHKDSK may give your hard disk a clean bill of health even if there are
bad sectors. This is because CHKDSK can only find files that have been
mis-allocated, it cannot find all physically damaged sectors. If CHKDSK
shows no errors, try installing the software program that's crashing into
a new, different directory. Then run the program from that directory. If
the program no longer crashes, the other copy of it may be stored on
The Last Resort
Before the existence of hard disk utilities like Norton DiskDoctor or
ScanDisk, we used the FORMAT command to thoroughly test a hard drive and
either repair or block off bad sectors. CAUTION: FORMAT erases all the
files on your hard drive, both document files and program files!
Before you reformat a drive, make a backup copy of all your files on
floppy diskettes, on tape, on removable disks, or an other hard drive. In
the absence of a hard disk utility like DiskDoctor or ScanDisk, you can
eliminate bad sectors by backing up all your files, reformatting the
drive, and then restoring all your files from the backup.
If any of the files you backed up were stored on bad sectors, they
may still be corrupt, so proceed to the final step.
The Final Step
After making sure that your drive has no bad sectors, if a file -- either
a program file or one of your personal documents -- was stored on a
damaged sector, you will probably have to restore the file from a backup,
or re-install the software program that contains that program file.
It may be difficult to tell which files were on the bad sectors. After
you've fixed the errors, try to run your programs and re-install
any programs or documents that misbehave.
Last Modified 17 Feb 1999