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Scandisk and CHKDSK (CheckDisk)

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Scandisk and CHKDSK (CheckDisk)
Last Updated: 06 May 2004

*** PLEASE NOTE: Link(s), If Provided, May Be Wrapped ***

The GUI-based SCANDISK utility which is familiar to users
of Windows 9x/ME is replaced in NT/2000/XP/2003 by CHKDSK,
which is entirely CLI-based.  Additionally, it requires
exclusive access to the drive in order to conduct repairs,
which means that on the drive where the OS is installed,
or a pagefile or other open file exists, you will require
a reboot to run CHKDSK in repair mode.  You can run it in
Read/Only mode to see if there are any issues which would
need to be corrected.

Windows 2000 and above provide access to this functionality
by way of Windows Explorer, but the same caveats apply in
terms of open files and exclusive disk access.

When using NTFS, you will find that the need for frequent
CHKDSKs are greatly reduced, as this is a very robust file
system.  FAT32 users will probably be more acquainted with
the utility.

Most 3rd party disk checking utilities for Windows NT/2000
are simply GUI interfaces to CHKDSK.  Later versions of
CHKDSK provide more functionality (much more than the old
DOS/Win3x/9x) versions in correcting file system issues.


CHKDSK can be run in, essentially, three modes:

	READONLY ------ CHKDSK C:     (or other drive)
	NORMAL FIX ---- CHKDSK C: /F  (or other drive)
	EXTENDED FIX -- CHKDSK C: /R  (or other drive)

The latter two modes require a reboot if the drive or
partition that they'll be running on has locked files
(e.g. the pagefile), so if you just want to find out
if you NEED to fix anything, simple run it in READONLY
mode.  If it doesn't complain that there are issues
that you need to correct, then you don't have to run
one of the more extensive scans.

Using the /F parameter will run a 3-step process to fix
files, indexes and free space. Using the /R parameter
will run a 5-step process which also addresses bad
sectors on the disk, and looks harder at the Master File
Table (MFT).

Occasionally, you will run a CHKDSK /F and after it has
finished, a read-only CHKDSK will indicate that there
are still problems.  This is almost always resolved by
running the 5-step CHKDSK /R or running CHKDSK via the
Recovery Console.  I'm not sure what causes CHKDSK /F
to be ineffective under these circumstances, but it
doesn't appear to happen very frequently.

For other CHKDSK options, see:  CHKDSK /?


For those more familiar to the GUI SCANDISK found in
Win9x, you can still perform a disk check in Windows
Explorer by doing the following:

	Open "My Computer"    (Press [WINKEY]+[E])
	Select a local drive
	Right-Click on the drive
	Select "Properties"
	Select the "Tools" tab
	Select "Check Now..."


On occasion, you my encounter the following error when
attempting to schedule a CHKDSK for next reboot:

"cannot open volume for direct access"

Use NTHANDLE or one of the other tools to establish what
process is holding access to the drive.  If this message
occurs during the reboot that should start the CHKDSK
process, then you need to boot into the Recovery Console
and run CHKDSK there.  Also, verify that the firmware for
your disk controller is up-to-date.










• VRFYDSK ................ Resource Kit -- Server 2003


• As with other console commands, you will want to open
  a CMD window and run CHKDSK inside of it so that you
  have an opportunity to see the output of the command.

• You can use CHKNTFS to control the behavior of CHKDSK
  in NT/2000/XP

• CHKDSK is also available under the Recovery Console

• In Win9x/ME, SCANDISK is preferred over CHKDSK, but
  under NT/2000/XP, CHKDSK is the preferred disk checking