CHKDSK

CHKDSK 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. It is short for "Check disk".

The command is implemented as an executable program file, CHKDSK.EXE. Different operating systems all use the same filename, but the files are not necessarily compatible between operating systems.

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.

Windows NT-based CHKDSK

CHKDSK can be run from the Windows Shell, the Windows Command Prompt or the Windows Recovery Console. One option for CHKDSK is the use of the Command-line/R parameter, which allows the program to repair damage it finds on the hard drive.

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 or Winlogon and can be viewed with the Event Viewer. On the Windows 7 operating system, look for events with a "Source" name of "Chkdsk"

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 (April 9, 1991). 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 gives more details on this.

Chkdsk information for Windows 7, Vista, XP 32-bit and 64-bit

Chkdsk.exe for Windows 7 Enterprise Edition 32-bit
Chkdsk.exe for Windows 7 Enterprise Edition 64-bit
Chkdsk.exe for Windows 7 Home Premium Edition 32-bit
Chkdsk.exe for Windows 7 Home Premium Edition 64-bit
Chkdsk.exe for Windows 7 Professional Edition 32-bit
Chkdsk.exe for Windows 7 Professional Edition 64-bit
Chkdsk.exe for Windows 7 Ultimate Edition 32-bit
Chkdsk.exe for Windows 7 Ultimate Edition 64-bit
Chkdsk.exe for Windows XP Home SP2
Chkdsk.exe for Windows XP Professional SP2
Chkdsk.exe for Windows XP Professional SP3
Chkdsk.exe for Windows XP Professional x64 SP1
Chkdsk.exe for Windows Vista Business SP1 32-bit
Chkdsk.exe for Windows Vista Home Basic SP1 32-bit
Chkdsk.exe for Windows Vista Home Premium SP1 32-bit
Chkdsk.exe for Windows Vista Ultimate SP1 32-bit