CHKNTFS.EXE: What You Can Use It For

Article ID: 160963 - View products that this article applies to.

System Tip

This article applies to a different version of Windows than the one you are using. Content in this article may not be relevant to you.

Visit the Windows 7 Solution Center

This article was previously published under Q160963

The Chkntfs.exe utility has been developed by Microsoft and is available in Microsoft Windows NT 4.0 Service Pack 2 and later versions of Windows. It is designed

to disable the automatic running of chkdsk on specific volumes, when Windows restarts from an improper shutdown. Chkntfs can also be used to unschedule a

chkdsk if chkdsk /f was used to schedule a chkdsk on an active volume on the next system restart.

Every time Windows restarts, Autochk.exe is called by the Kernel to scan all volumes to check if the volume dirty bit is set. If the dirty bit is set, autochk performs

an immediate chkdsk /f on that volume. CHKDSK /f verifies file system integrity and attempts to fix any problems with the volume. It is always advisable to run

chkdsk on volumes that have been improperly shutdown, however, there may be some situations in which running chkdsk after every improper shutdown is not

possible or practical. In some cases, chkdsk may take several hours or even days to completely check the volume or may hang while checking the volume. In these

situations, it is more practical to postpone the chkdsk until a more convenient time.

Chkntfs is a utility that enables a system administrator to exclude volumes from being checked by the autochk program. The utility is run from a command

prompt and has the following command line options:

If no switches are specified, chkntfs displays the status of the dirty bit for each drive.

Examples:

chkntfs /x c: This disables chkdsk from running on drive C:

chkntfs /x d: e: This disables chkdsk from running on drives D: and E:.

The chkntfs /x commands are not cumulative, the command overwrites any previous drive exclusions that have been established. In the above example, chkntfs

only disables the chkdsk checking on drives D and E, drive C is not checked for the presence of a dirty bit.

The chkntfs utility works by modifying the BootExcecute value in the system registry. The BootExecute value is located in the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CURRENTCONTROLSET\CONTROL\Session Manager

The default value is:

BootExecute:REG_MULTI_SZ:autocheck autochk *

Chkntfs /x adds a /k parameter prior to the asterisk. The /k parameter excludes volumes from being checked for the presence of a dirty bit.

For example, the command

chkntfs /x D:

would modify this registry entry to autocheck autochk /k:d *

Chkdsk /f schedules itself to run at the next reboot by setting the dirty bit on the drive. Chkdsk /x disables the checking for this bit. Chkdsk /f can never run on

volumes that are excluded from dirty bit checking by chkntfs.

In order to run a chkdsk /f on a drive that has been excluded by the chkntfs utility, you must run the chkntfs /d option to return the system to its normal state or

edit the BootExecute value in the registry and remove the applicable drive letter from the /k parameter.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry

incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the

SUMMARY

MORE INFORMATION

chkntfs drive: [...] chkntfs /d chkntfs /x drive: [...] chkntfs /c drive: [...] drive: Specifies a drive letter. /D Restores

the machine to the default behavior; all drives are checked at boot time and chkdsk is run on those that are dirty. This

undoes the effect of the /X option. /X Excludes a drive from the default boot-time check. Excluded drives are not accumulated

between command invocations. /C Schedules chkdsk to be run at the next reboot if the dirty bit has been set.

Find it myself

Ask the community

Get live help

Select the product you need help with

Windows Internet

Explorer

Office Surface Media Player Skype Windows

Phone

More products

CHKNTFS.EXE: What You Can Use It For http://support.microsoft.com/?kbid=160963

1 of 2 10/31/2012 8:50 PM

registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the

Microsoft Knowledge Base:

322756 (http://support.microsoft.com/kb/322756/ ) How to back up and restore the registry in Windows

Chkdsk /f /r enables chkdsk to check volumes for file system errors and bad sectors on the physical disk. Chkdsk /f /r schedules itself to be run on the next system

reboot, by adding an entry into the BootExecute value. For example,

chkdsk c: /f /r

adds the following entry to the BootExecute value:

Because this entry is actually placed in the registry, the chkdsk /f /r is unaffected by any chkntfs commands. The only way to disable a chkdsk /f /r is to remove

the line from the BootExecute value that references this command.

The Chkntfs.exe utility treats all drives as local to the node. This includes Microsoft Cluster Server (MSCS) physical disk resources on a shared drive array. When

using Chkntfs.exe to exclude shared drives on a cluster, you must run the exlusion command on each node. This must be done to ensure each node's registry will

have the proper entries. You can only run the command for the shared drive(s) that node owns. If the node does not own the physical disk resource you will

receive an error.

Article ID: 160963 - Last Review: February 22, 2007 - Revision: 3.3

APPLIES TO

Microsoft Windows 2000 Server

Microsoft Windows 2000 Advanced Server

Microsoft Windows 2000 Professional Edition

Microsoft Windows 2000 Datacenter Server

Microsoft Windows NT Workstation 4.0 Developer Edition

Microsoft Windows NT Server 4.0 Standard Edition

Microsoft Windows Server 2003 Service Pack 1

Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)

Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)

Microsoft Windows Server 2003, Standard Edition (32-bit x86)

Microsoft Windows Server 2003, Web Edition

Keywords: kbhowto KB160963

Back to the top

autocheck autochk /r \??\C:

Properties

Give Feedback

CHKNTFS.EXE: What You Can Use It For http://support.microsoft.com/?kbid=160963

2 of 2 10/31/2012 8:50 PM