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How to Check a Disk for Errors (CHKDSK) in Batch Script

Maintaining the health of a file system is a critical administrative task. Over time, disks can develop logical errors in the file system or even physical bad sectors, leading to data corruption or system instability. The standard Windows tool for detecting and repairing these issues is Check Disk (chkdsk.exe). From a batch script, you can automate this process to run as part of a scheduled maintenance routine or as a prerequisite before a critical operation like a full backup.

This guide will teach you how to use the CHKDSK command from a batch script, explain its most important parameters for finding and fixing errors, and show you how to interpret its exit codes to determine the health of your drive.

What is CHKDSK?​

CHKDSK is a powerful command-line utility that verifies the logical integrity of a file system. It can:

  • Scan for logical errors: Check for inconsistencies in the file system's master file table (MFT), security descriptors, and other metadata.
  • Fix logical errors (/F): Correct these inconsistencies to restore the file system to a healthy state.
  • Scan for physical errors (/R): Scan the entire disk surface for bad sectors and attempt to recover readable information from them.

The Core Command: CHKDSK​

The basic syntax for the Check Disk utility is straightforward.

CHKDSK [volume] [parameters]

  • [volume]: The drive letter you want to check, followed by a colon (e.g., C:, D:).
  • [parameters]: Switches that control the behavior of the scan (e.g., /F to fix errors).

Basic Example: A Read-Only Scan​

If you run CHKDSK with only a drive letter, it performs a read-only scan. It will report any errors it finds but will not attempt to fix them. This is a safe way to check the status of a drive without making any changes.

@ECHO OFF
ECHO --- Performing a read-only scan of the C: drive ---
ECHO This may take some time...
ECHO.
CHKDSK C:
note

The output will be a multi-stage report on the health of the file system.

Key Parameters for Repairing Disks (/F, /R, /X)​

To make CHKDSK useful for maintenance, you must use its repair parameters. These actions require administrator privileges.

  • /F: Fixes errors on the disk. This is the most common parameter. CHKDSK will attempt to lock the drive to perform repairs. If it can't, it will prompt to run on the next reboot.
  • /R: Locates bad sectors and Recovers readable information. This implies /F (it does everything /F does, plus a full surface scan). This is a much longer and more intensive process.
  • /X: Forces the volume to dismount first, if necessary. This can help if files are in use. CHKDSK /X also implies /F.

A common command for a thorough check and repair is CHKDSK D: /F /X.

Interpreting the Results (%ERRORLEVEL%) for Scripts​

For automation, you need to know if the scan was successful. CHKDSK sets the %ERRORLEVEL% variable to indicate the outcome.

  • 0: No errors were found.
  • 1: Errors were found and fixed.
  • 2: Did not perform repair because /F was not specified.
  • 3: Could not check the disk, errors were found but could not be fixed, or errors were not fixed because /F was not specified. This indicates a failure.

A script to check the result

@ECHO OFF
CHKDSK D: /F

IF %ERRORLEVEL% LSS 2 (
    ECHO [SUCCESS] The drive is clean or was successfully repaired.
) ELSE (
    ECHO [FAILURE] The drive has errors that were not fixed.
)

Common Pitfalls and How to Solve Them​

Problem: The Script is Not Run as Administrator​

If you use /F or /R without elevated privileges, the command will fail.

Example of script with error:

Access Denied as you do not have sufficient privileges.
You have to invoke this utility running in elevated mode.

Solution: The script must be run as an Administrator. Right-click the .bat file or cmd.exe and select "Run as administrator."

Problem: "Cannot lock current drive" (Checking the System Drive)​

You cannot run CHKDSK /F on the system drive (C:) while Windows is running because the drive is in use. When this happens, CHKDSK will ask you an interactive question.

Example of the prompt:

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? (Y/N)

This prompt will halt any unattended script, waiting for input.

Solution: Pipe "Y" to the Command​

You can automate answering "Yes" to this prompt by piping the Y character into the command.

@ECHO OFF
REM This command answers "Y" to the reboot prompt automatically.
ECHO Y | CHKDSK C: /F /R
note

This will schedule the disk check and allow your script to continue without getting stuck.

Practical Example: A Scheduled Disk Health Check Script​

This script is designed to be run as a scheduled task. It checks a data drive for errors and logs the result.

@ECHO OFF
SETLOCAL
SET "TARGET_DRIVE=D:"
SET "LOG_FILE=C:\Logs\DiskHealth.log"

ECHO %DATE% %TIME% - Starting check of drive %TARGET_DRIVE% >> "%LOG_FILE%"

CHKDSK %TARGET_DRIVE% /F

IF %ERRORLEVEL% EQU 0 (
    ECHO %DATE% %TIME% - RESULT: Success. No errors found. >> "%LOG_FILE%"
) ELSE IF %ERRORLEVEL% EQU 1 (
    ECHO %DATE% %TIME% - RESULT: Success. Errors were found and fixed. >> "%LOG_FILE%"
) ELSE (
    ECHO %DATE% %TIME% - RESULT: FAILURE. Chkdsk failed with code %ERRORLEVEL%. >> "%LOG_FILE%"
)

ECHO %DATE% %TIME% - Check complete. >> "%LOG_FILE%"
ECHO. >> "%LOG_FILE%"

ENDLOCAL

Conclusion​

The CHKDSK command is an essential utility for automating disk maintenance. By using it within a batch script, you can ensure the integrity of your file systems as part of a regular schedule.

Key takeaways for scripting with CHKDSK:

  • Run CHKDSK D: for a safe, read-only scan.
  • Use CHKDSK D: /F to find and fix logical errors.
  • You must run as an Administrator to use the /F or /R parameters.
  • Check the %ERRORLEVEL% to determine the outcome of the scan for your script's logic.
  • To run a fixing scan on the system drive (C:), you must schedule it for the next reboot by piping "Y" into the command: ECHO Y | CHKDSK C: /F.

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