CHKDSK Windows cmd line tool – Microsoft overview

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Here’s microsoft’s overview of the CHKDSK Windows command line tool.  An in-depth discussion can be found here.

Quote microsoft:


Creates and displays a status report for a disk based on the file system. Chkdsk also lists and corrects errors on the disk. Used without parameters, chkdsk displays the status of the disk in the current drive.


chkdsk [volume:][[Path] FileName] [/f] [/v] [/r] [/x] [/i] [/c] [/l[:size]]


volume: : Specifies the drive letter (followed by a colon), mount point, or volume name.

[Path] FileName : Specifies the location and name of a file or set of files that you want chkdsk to check for fragmentation. You can use wildcard characters (that is, * and ?) to specify multiple files.

/f : Fixes errors on the disk. The disk must be locked. If chkdsk cannot lock the drive, a message appears that asks you if you want to check the drive the next time you restart the computer.

/v : Displays the name of each file in every directory as the disk is checked.

/r : Locates bad sectors and recovers readable information. The disk must be locked.

/x : Use with NTFS only. Forces the volume to dismount first, if necessary. All open handles to the drive are invalidated. /x also includes the functionality of /f.

/i : Use with NTFS only. Performs a less vigorous check of index entries, reducing the amount of time needed to run chkdsk.

/c : Use with NTFS only. Skips the checking of cycles within the folder structure, reducing the amount of time needed to run chkdsk.

/l[:size] : Use with NTFS only. Changes the log file size to the size you type. If you omit the size parameter, /l displays the current size.

/?: Displays help at the command prompt.


Running chkdskTo run chkdsk on a fixed disk, you must be a member of the Administrators group.
Checking a locked drive at restartIf you want chkdsk to correct disk errors, you cannot have open files on the drive. If files are open, the following error message appears:Chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)If you choose to check the drive the next time you restart the computer, chkdsk checks the drive and corrects errors automatically when you restart the computer. If the drive partition is a boot partition, chkdsk automatically restarts the computer after it checks the drive.
Reporting disk errorsChkdsk examines disk space and disk use for the file allocation table (FAT) and NTFS file systems. Chkdsk provides information specific to each file system in a status report. The status report shows errors found in the file system. If you run chkdsk without the /f command-line option on an active partition, it might report spurious errors because it cannot lock the drive. You should use chkdsk occasionally on each disk to check for errors.
Fixing disk errorsChkdsk corrects disk errors only if you specify the /f command-line option. Chkdsk must be able to lock the drive to correct errors. Because repairs usually change a disk’s file allocation table and sometimes cause a loss of data, chkdsk sends 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 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 fixes the disk, but it does not save the contents of the lost allocation units.

If you do not use the /f command-line option, chkdsk sends a message if a file needs to be fixed, but it does not fix any errors.

If you use chkdsk /f on a very large disk (for example, 70 gigabytes) or a disk with a very large number of files (for example, millions of files), chkdsk might take a long time (for example, over several days) to complete. The computer is not available during this time because chkdsk does not relinquish control until it is finished.

Checking a FAT diskWindows displays chkdsk status reports for a FAT disk in the following format:Volume Serial Number is B1AF-AFBF72214528 bytes total disk space73728 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 diskWindows 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.

Using chkdsk with open filesIf you specify the /f command-line option, chkdsk sends an error message if there are open files on the disk. If you do not specify the /f command-line option 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.
Finding physical disk errorsUse the /r command-line option to find physical disk errors in the file system. For information about recovering physically damaged files with recover, see Related Topics.
Reporting bad disk sectorsBad sectors reported by chkdsk were marked as bad when your disk was first prepared for operation. They pose no danger.
Understanding exit codesThe following table lists the exit codes that chkdsk reports after it has finished.

Exit code Description
0 No errors were found.
1 Errors were found and fixed.
2 Disk cleanup, such as garbage collection, was performed, or cleanup was not performed because /f was not specified.
3 Could not check the disk, errors could not be fixed, or errors were not fixed because /f was not specified.
The chkdsk command, with different parameters, is available from the Recovery Console.


If you want to check the disk in drive D and have Windows fix errors, type:

chkdsk d: /f

If it encounters errors, chkdsk pauses and displays messages. Chkdsk finishes by displaying a report that lists the status of the disk. You cannot open any files on the specified drive until chkdsk finishes.

To check all of files on a FAT disk in the current directory for noncontiguous blocks, type:

chkdsk *.*

Chkdsk displays a status report, and then lists the files matching the file specification that have noncontiguous blocks.

Formatting legend

Format Meaning
Italic Information that the user must supply
Bold Elements that the user must type exactly as shown
Ellipsis (…) Parameter that can be repeated several times in a command line
Between brackets ([]) Optional items
Between braces ({}); choices separated by pipe (|). Example: {even|odd} Set of choices from which the user must choose only one
Courier font Code or program output

Command-line reference A-Z

End quoting microsoft:


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