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This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (May 2008) |
 Chkdsk.exe in action on drive C: |
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| Design by | Microsoft |
|---|---|
| OS | MS-DOS and NT-based versions of Windows |
| Platform | x86 |
| Available in | English |
| Type | System tool |
| License | Commercial (part of MS-DOS and Windows). |
CHKDSK (short for Checkdisk) is a command on computers running DOS, OS/2 and Microsoft Windows operating systems that displays the file system integrity status of hard disks and floppy disk and can fix logical file system errors. It is similar to the fsck command in Unix.
On computers running NT-based versions of Windows, CHKDSK can also check the disk surface for physical errors or bad sectors, a task previously done by SCANDISK. This version of CHKDSK can also handle some physical errors and recover data that is still readable.
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Windows NT-based CHKDSK
CHKDSK can be run from the Windows Shell, the Windows Command Prompt or the Windows Recovery Console.
Conducting a CHKDSK can take some time, especially if using the /R parameter, and the results are often not visible, for various reasons. The results of a CHKDSK conducted on restart using Windows 2000 or later operating systems are written to the Application Log, with a "Source" name of Wininit, and can be viewed with the Event Viewer.
A typical result:
Checking file system on C:
The type of the file system is NTFS.
A disk check has been scheduled.
Windows will now check the disk.
Cleaning up minor inconsistencies on the drive.
Cleaning up 318 unused index entries from index $SII of file 0x9.
Cleaning up 318 unused index entries from index $SDH of file 0x9.
Cleaning up 318 unused security descriptors.
CHKDSK is verifying file data (stage 4 of 5)...
File data verification completed.
CHKDSK is verifying free space (stage 5 of 5)...
Free space verification is complete.
14996645 KB total disk space.
10187752 KB in 88054 files.
30784 KB in 5774 indexes.
0 KB in bad sectors.
164341 KB in use by the system.
65536 KB occupied by the log file.
4613768 KB available on disk.
4096 bytes in each allocation unit.
3749161 total allocation units on disk.
1153442 allocation units available on disk.
Known issues
File system checking programs are designed to repair faulty file systems. However, other types of errors can also cause errors in the file system, which may cause these programs to run automatically. However, since the original problem is not of the type these programs can handle, they may cause even bigger problems, making data recovery much harder. Windows XP and Windows 2000 may start these programs without first asking and then 'repair' any errors they find without asking. For this reason, data recovery experts usually advise customers to stop these programs before they can do any damage by hitting 'ESC' (for which one has 10 seconds), or to even disable them completely. [1]
Sometimes the check after CHKDSK invoked with the /f or /r option on reboot still fails, giving the error "Cannot open volume for direct access" on startup, due to an application (anti-virus, anti-spyware, firewall, and the like) that locks up the partition before CHKDSK can access it. This has been improved in Windows XP Service Pack 2, but still happens occasionally. One fix is to set the /SAFEBOOT option in the boot.ini tab after running msconfig.[1] This puts the system in a minimal/low-resolution mode.
DOS-based CHKDSK
The MS-DOS 5 bug
The version of CHKDSK (and Undelete) supplied with MS-DOS 5.0 has a bug which can corrupt data. This applies to CHKDSK.EXE and UNDELETE.EXE with a date of 04/09/91. If the file allocation table of a disk uses 256 sectors, running CHKDSK /F can cause data loss and running UNDELETE can cause unpredictable results. This normally affects disks with a capacity of approximately a multiple of 128 MB. This bug was fixed in MS-DOS 5.0a. A Microsoft Knowledge Base article[2] gives more details on this.
See also
External links
- Microsoft TechNet Chkdsk article
- Understanding what CHKDSK does (NTFS only) – Microsoft Article
- Graphical CHKDSK Walkthrough – Covering both Windows and Command line options
- How to Use Chkdsk in Windows XP – Also explains how the program works
- Troubleshooting Disks and File Systems - TechNet Article on Windows XP resources to troubleshoot hard disk errors
References
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