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How to Use Chkdsk

Check Your Hard Drive for Errors

Hard DriveChkdsk inspects the physical structure of a Hard Drive or SSD's to make sure that they are healthy. It can then repair any drive problems that it finds, related to bad sectors, lost clusters, cross-linked files and directory errors.

These types of problems can arise in a variety of ways. System restarts, crashes or freezes, power glitches and incorrectly turning off a computer, can cause all sorts of corruption in the drives file or folder structure.

Once an error occurs it can develop to create more errors, so regularly running Chkdsk should be made part of your routine PC maintenance.

Chkdsk can also serve as an early warning that a hard drive or SSD is deteriorating. Drives gradually wear out and sectors may become bad. If Chkdsk starts finding bad sectors, that's a sign that your drive may need replacing.

The Security of the NT File System

The NT file system itself has a built in recovery system. If a drive becomes corrupted, the NT file system runs a recovery procedure that accesses information stored in a transaction log file. The NT file system recovery procedure guarantees that the drive volume will be restored to a consistent state. For this reason, it is unlikely that NTFS volumes will become corrupted. So the /R switch (see the table opposite) is usually not essential, but it can be used as a convenient mechanism for scanning the entire volume of a disk if it is suspected of having bad sectors.

Bad sectors can certainly cause problems with shutting down and rebooting so a good tip is to run Chkdsk with the /R switch enabled. This setting can repair any problems that might be developing on your computers hard disk.

As the Chkdsk tool has built-in support for the NT file system you can run this from a Windows command prompt. To do this, Click Start and then click Run. In the Run box type cmd. Right click the CMD Prompt app and select Run as Administrator. When you arrive at the command prompt type
CHKDSK C:   /R (i.e. repair your C Drive) and hit Enter.

If the following message appears: “Cannot lock current drive. Chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts?” type Y and hit Enter.

Now reboot your computer so that Chkdsk can automatically run and check the hard drive for errors. It will then attempt to repair these.

This simple process will usually fix the shut-down and restarting problems on most Windows machines.

Be aware that if your PC's drive is heavily fragmented and contains a lot of files Chkdsk's performance will be very slow and will take several hours to complete. For this reason it's a good idea to run Chkdsk overnight, at a time when you are not using your PC.

Running Chkdsk from the Recovery Console

Chkdsk is also available from the Windows Recovery Console.

To use this route you will need a full copy of Windows and the boot order in the BIOS must be set so that the CD drive is the first in the list.

Place the CD into your CD/DVD Drive and reboot your computer. When you arrive at the install menu choose to repair using the Recovery Console (NOT AUTORECOVERY which shows during the loading phase of a CD Boot).

When you arrive at the Recovery Console DOS prompt type CHKDSK C:  /R and hit Enter.

If you have multiple partitions, type D: and press Enter.
Now run chkdsk /r again i.e. CHKDSK D:  /R

Many systems have been rescued by the Windows Recovery Console command CHKDSK C:  /R.

Note: Switches for the Chkdsk command in the Recovery Console are not the same as those in Table opposite. There are only two available.

/P, which does an exhaustive check of the drive and corrects any errors. It does not check for bad sectors.

/R : which locates bad sectors and recovers readable information and includes all the functions of /P.

How Chkdsk Works - the Switches

Chkdsk can be run with or without a range of switches. The switches can cut down the time it takes to complete a full Chkdsk sweep.

/F Fixes errors on the disk. Does not scan for bad sectors.
/V On FAT/FAT32: Displays the full path and name of every file on the disk. On NTFS: Displays cleanup messages if any.
/R Locates bad sectors and recovers readable information (implies /F).
/X NTFS only: Forces the volume to dismount first if necessary.
/I NTFS only: Performs a less vigorous check of index entries.
/C NTFS only: Skips checking of cycles within the folder structure.
/L [:size] NTFS only: Changes the log file size to the specified number of kilobytes.

The Processes Chkdsk Performs

Phase 1: Checking files

During its first pass, Chkdsk examines each file record segment in the volume's master file table (MFT) and examines it for internal consistency. At the end of this phase, Chkdsk has identified the space that is in use and the space that is available, both within the MFT and on the volume as a whole.

Phase 2: Checking indexes (directories)

During this pass, Chkdsk examines each directory that is on the volume, checking for internal consistency and verifying that every file and directory that is represented by a file record segment in the master file table (MFT) is referenced by at least one directory. Chkdsk confirms that every file or subdirectory that is referenced in a directory actually exists as a valid file record segment in the MFT and also checks for circular directory references. Finally, Chkdsk confirms that the time stamps and file size information for the files are up-to-date in the directory listings for those files. At the end of this phase, Chkdsk has made sure that there are no "orphaned" files and that all directory listings are for legitimate files.

Phase 3: Checking security descriptors

During this phase, Chkdsk examines each security descriptor that is associated with files or directories on the volume. Security descriptors contain information about ownership of a file or directory, about NTFS permissions for the file or directory, and about auditing for the file or directory.

Phases 4 and 5: Checking sectors (optional)

If the /R switch is in effect, Chkdsk runs two more passes to look for bad sectors that it can repair. During stage 4, Chkdsk verifies all the sectors in use ; during stage 5, Chkdsk verifies and actions unused clusters.


Interrupting the Chkdsk process when it is used with the /F or the /R switch is not recommended. The integrity of the disk can be compromised by stopping the process.

If you are subject to power failures during bad weather we suggest you invest in an uninterruptible power supplyto guard against short-term power outages or fluctuations. This is especially important when using Chkdsk with the /F or the /R switch.

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