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Church Of The
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Chkdsk examines disk space and use for the NTFS and FAT file systems. Information specific to each file system is provided in a status report. The status report shows errors found in the file system.

If errors exist on the disk, chkdsk alerts you with a message and corrects the errors if the /f switch was used. Chkdsk must be able to lock the drive to correct errors. If errors are found but the drive cannot be locked, an error message is displayed. If you run chkdsk without the /f switch on an active partition, it may report spurious errors, since it will not lock the volume.

You should use chkdsk occasionally on each disk to check for errors.

Checking a locked drive at reboot

Files cannot be open on a drive when chkdsk corrects disk errors it finds. If files are open chkdsk offers to check the drive the next time the computer reboots. If you choose to check the drive the next time the computer reboots, the drive will be checked and errors will be corrected automatically at reboot. If the drive partition is a boot partition, upon completion it will reboot the computer.

Checking a FAT disk

Windows NT displays chkdsk status reports for a FAT disk in the following format:

Volume Serial Number is B1AF-AFBF

72214528 bytes total disk space

73728 bytes in 3 hidden files

30720 bytes in 12 directories

11493376 bytes in 386 user files

61440 bytes in bad sectors

60555264 bytes available on disk

2048 bytes in each allocation unit

35261 total allocation units on disk

29568 available allocation units on disk

Checking an NTFS disk

Windows NT displays chkdsk status reports for an NTFS disk in the following format:

The type of the file system is NTFS.

CHKDSK is verifying files...

File verification completed.

CHKDSK is verifying indexes...

Index verification completed.

CHKDSK is verifying security descriptors...

Security descriptor verification completed.

12372 kilobytes total disk space.

3 kilobytes in 1 user files.

2 kilobytes in 1 indexes.

4217 kilobytes in use by the system.

8150 kilobytes available on disk.

512 bytes in each allocation unit.

24745 total allocation units on disk.

16301 allocation units available on disk.

Fixing disk errors

The chkdsk command corrects disk errors only if you specify the /f switch. Since repairs usually change a disk's file allocation table and sometimes cause a loss of data, chkdsk first prompts you with a confirmation message similar to the following:

10 lost allocation units found in 3 chains.

Convert lost chains to files?

If you press Y, Windows NT saves each lost chain in the root directory as a file with a name in the format FILEnnnn.CHK. When chkdsk finishes, you can check these files to see if they contain any data you need. If you press N, Windows NT fixes the disk but does not save the contents of the lost allocation units.

If you do not use the /f switch, chkdsk alerts you with a message if a file needs to be fixed but does not fix the error(s).

If you use chkdsk /f on a very large disk (for example, 70 GB) or a disk with a very large number of files (millions), chkdsk may take a long time (perhaps days) to complete. The computer will not be available during this time, as chkdsk does not relinquish control until it is done.

Using chkdsk with open files

If you specify the /f switch, chkdsk shows an error if open files are found on the disk. If you do not specify the /f switch and open files exist, chkdsk might report lost allocation units on the disk. This could happen if open files have not yet been recorded in the file allocation table. If chkdsk reports the loss of a large number of allocation units, consider repairing the disk.

Physical disk errors

Use the /r switch to find physical disk errors in the file system. For information about recovering physically damaged files, see the recover command.

Bad disk sectors

Bad sectors reported by chkdsk were marked as "bad" when your disk was first prepared for operation. They pose no danger.

Exit codes

No errors were found
Errors were found and fixed.
Could not check the disk, errors could not be fixed, or errors were not fixed because /f was not specified.

More Information About Chkdsk

ntcmds00000001.gif Chkdsk--Examples

ntcmds00000001.gif Chkdsk


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