Chkdsk : CheckDisk Command

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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.

Syntax :
chkdsk [volume:][[Path] FileName] [/f] [/v] [/r] [/x] [/i] [/c] [/l[:size]]
Parameters
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.
Remarks
􀁺 Running chkdsk
To run chkdsk on a fixed disk, you must be a member of the Administrators group.
􀁺 Checking a locked drive at restart
If 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 errors
Chkdsk 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.
z Fixing disk errors
Chkdsk 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.
z Checking a FAT disk
Windows 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
z Checking an NTFS disk
Windows 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.