Windows NT will run the CHKDSK /F program the next time it reboots depending on the status of the Dirty Bit for each NTFS partition. There is no way to clear permanently the Dirty Bit once it has been set, except by running CHKDSK /F. However, there is a way to prevent the running of CHKDSK /F on NTFS partitions when Windows NT reboots. You may want to do this to retrieve some file segments before CHKDSK permanently rearranges the files on your NTFS partition. Since the Dirty Bit is set when an abnormal system termination has occurred, preventing CHKDSK /F to run should only be done as a temporary stopgap measure until normal Windows NT operation can be restored.
The CHKNTFS utility allows you to override the normal behavior of CHKDSK /F at boot time. When you run CHKNTFS /?, it will display the following help.
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 no switches are specified, CHKNTFS will display the status of the dirty bit for each drive.
CHKNTFS does not modify the Dirty Bit, but is sets or clears a flag in the Registry that overrides the behavior of CHKDSK /F. The Registry entry is
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\BootExecute
Normally it is set to
autocheck autochk *
CHKNTFS adds or removes override lines for individual NTFS partitions, e.g. to prevent CHKDSK /F from running for NTFS partition D: the entry becomes:
autocheck autochk *
autocheck autochk /k:D
When you scheduled the CHKDSK /F for drive D: when the Dirty Bit was not set with the /C option, the entry becomes
autocheck autochk *
autocheck autochk /m:D
In addition, you must have Administrator priveleges to run the CHKNTFS command. The file CHKNTFS.EXE is installed as part of Service Pack 2 for Windows NT 4.0. and placed in the \Winnt\System32 directory.