CHKDSK: What It Is & How to Run It & Fix Common CHKDSK Errors

Part 1. Introduction

What Is CHKDSK

CHKDSK is a command-line tool in Windows used to check and repair local hard drives, solid-state drives, or removable drives.

It scans for file system errors, marks bad sectors, and recovers readable information.

CHKDSK helps protect the security and stability of your disk, data, and system, as a corrupted file system can lead to disk inaccessibility or even system failure.

Wondering when you need to run CHKDSK? Keep reading.

When to Run CHKDSK

Typically, you should run CHKDSK when your disk shows problems or the system runs into performance issues.

Let’s explore the details.

Common Signs You Need to Run CHKDSK

Typically, you should run CHKDSK if you notice any of the following signs:

• Disk access issues. If a disk cannot be accessed and warnings like “Location is not available” appear, this often indicates file system corruption or bad sectors.
• System instability or crashes. Abnormal shutdowns, blue screens, or black screens may indicate logical errors on the system disk.
• Performance degradation. A long system boot time or occasional spinning circle when accessing files may hint at disk errors.
• Unusual disk behavior. Frequent delays when opening files or strange clicking sounds of your disk may suggest read/write failures or file system problems.

When you encounter these issues, running CHKDSK can help repair the disk or rule out file system problems.

Should you always run CHKDSK manually? Not necessarily. Windows can run it automatically without manual intervention.

Automatic CHKDSK Check

When Windows detects abnormal situations, such as unexpected shutdowns or file system errors, it may mark the affected disk as dirty. On the next restart, CHKDSK will run automatically to scan and repair errors.

Once the errors are fixed, the system will mark the disk as clean, and CHKDSK will no longer run automatically on the next startup.

This mechanism helps maintain file system integrity and prevents minor issues from developing into serious disk or system failures.

Preventive vs. Reactive Check

There are generally two ways CHKDSK runs: you can run it manually, or Windows runs it automatically if the system detects a dirty disk. 

With preventive checks, you can perform maintenance at convenient times when the system is idle, and avoid long startup delays caused by reactive checks.

After understanding the basics of CHKDSK, let’s see how to run it with or without additional parameters.

Part 2. Understanding CHKDSK Commands

This section explains CHKDSK’s basic usage and common parameters.

How to Run CHKDSK on Windows

You can run CHKDSK either through the Command Prompt or using File Explorer. Follow the instructions below for each method.

How to Run CHKDSK From Command Prompt

Here is how to execute the CHKDSK command from Command Prompt to examine the basic file system structure, file name linkage, and security descriptors of your drive.

Step 1. Type cmd in the Windows search bar, right-click Command Prompt, and choose Run as administrator.

Step 2. If the UAC window appears, click Yes to continue.

Step 3. Type chkdsk and press Enter.

Without any additional parameters, CHKDSK runs in read-only mode and quickly checks the current disk (usually the C: drive) without fixing any errors.

The most commonly used CHKDSK parameters and their usage for disk repair are explained below.

How to Run CHKDSK From Windows Explorer

File Explorer’s error-checking tool provides a similar function to the CHKDSK command. It offers a more intuitive graphical interface for checking file system errors.

Unlike CHKDSK, this tool cannot scan for bad sectors and does not allow parameter customization. It is more suitable for users who are not familiar with command lines.

Here is how to run CHKDSK in File Explorer:

Step 1. Press Windows + E to open File Explorer.

Step 2. Right-click the target drive and choose Properties.

Step 3. Go to the Tools tab, and click Check under the Error checking section.

Step 4. Click Scan drive to begin the process.

The steps above cover how to basically check (and repair) file system errors by using CMD or the error-checking tool.

If you want to perform more advanced repairs or customize how CHKDSK runs, continue reading for the CHKDSK command parameters.

CHKDSK Key Parameters Explained

Syntax of the CHKDSK Command

The basic syntax of the CHKDSK command is:

chkdsk [<volume>[[<path>]<filename>]] [/f] [/v] [/r] [/x] [/i] [/c] [/l[:<size>]] [/b] [/scan] [/forceofflinefix] [/perf] [/spotfix] [/sdcleanup] [/offlinescanandfix] [/freeorphanedchains] [/markclean] [/?]

As defined in the syntax, CHKDSK supports a wide range of parameters. They are used to perform advanced disk repair tasks, such as repairing file system errors, detecting and isolating bad sectors, dismounting a volume forcibly, and more.

However, you do not need to use all these parameters every time you run CHKDSK.

Below are the most commonly used parameters and their purposes.

So, for example, to repair the E: drive, execute CHKDSK E: /f /r /x /v.

Other parameters are generally not needed for typical users and are mainly used by advanced users or IT professionals. Check Microsoft’s official CHKDSK documentation for the complete list of supported parameters.

CHKDSK on HDDs vs SSDs: Performance & Limitations

While CHKDSK can be applied to both HDDs and SSDs, the performance and considerations differ depending on the drive type.

HDDs use spinning magnetic platters. Due to this mechanical design, the read/write head must physically move to each data location when running CHKDSK. This makes the scan slower, especially on large drives.

In contrast, SSDs have no moving parts. As a result, CHKDSK scans are generally faster, even when using /r for a complete surface scan and repair.

However, although /r runs quickly on SSDs, repeated full surface scans may increase write and erase cycles, which can slightly reduce the drive’s lifespan.

Difference Between HDD & SSD Considerations

Considering the limitations of HDDs and SSDs, before running CHKDSK, some precautions should be taken.

For large HDDs, it is best to schedule scans during non-working hours, as interrupting CHKDSK midway is not recommended.

For SSDs, you need to avoid unnecessary /r scans.

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Part 3. Advanced CHKDSK Operations

This section explains some advanced CHKDSK operations for professional use.

The following content covers how to:

• Schedule a CHKDSK scan to run at system startup.
• Cancel a scheduled disk check if needed.
• Run CHKDSK when the computer is not bootable.
• Access and review CHKDSK logs to understand the scan results.

Force a CHKDSK on Startup

Some users prefer to let Windows automatically check their drives for file system errors at startup, without having to type the CHKDSK command manually each time.

However, Windows does not yet provide an option to schedule CHKDSK for every boot.

Forcing CHKDSK to run on startup is valid only when the drive is in use (especially the system drive) or marked as dirty.

Run CHKDSK on an active drive:

Step 1. Open an administrative Command Prompt.

Step 2. Type chkdsk C: /f /r and press Enter.

You will receive a message stating that CHKDSK cannot run because the volume is in use and asking if you want to schedule a check at the next system restart.

Step 3. Type Y and press Enter. Then, CHKDSK will run automatically the next time you start your PC.

Force a drive into a dirty state:

You can also manually set the drive as dirty using the fsutil command to trigger CHKDSK automatically at the next startup.

In an administrative Command Prompt window, type fsutil dirty set drive letter: and press Enter. Replace drive letter with the actual letter of the drive you suspect has file system errors.

This command marks the drive as dirty, forcing CHKDSK to run automatically the next time you restart your computer.

Change Scheduled Disk Checks (Chktnfs)

If you have scheduled an automatic disk check to run the next time your computer starts but now want to cancel it, the chkntfs command can help.

Chkntfs is used to display or modify the automatic disk checking behavior. You can use it to cancel a scheduled check or change the Autochk.exe initiation countdown time.

Below, I will use the C: drive for example.

Check if a drive is scheduled for a disk check:

Open Command Prompt as an administrator. Then type chkntfs C: and press Enter.

You may see one of the following results:

• CHKDSK is scheduled: Chkdsk has been scheduled manually to run on the next reboot on volume C:.
• CHKDSK is not scheduled: C: is not dirty.

Cancel an automatic disk check:

If CHKDSK is scheduled, type chkntfs /x C: and press Enter.

This command excludes the drive from being checked during startup.

To confirm it, run chkntfs C: again, and check the output message.

Change the Autochk.exe initiation countdown time:

By default, an automatic disk check starts several seconds after the system boots.

If you want to change this countdown time, type chkntfs /t:time and press Enter. For example, run chkntfs /t:30 to set it to 30 seconds.

Run CHKDSK on an Unbootable Computer

If your system fails to boot normally, there may be issues with the system drive. Running CHKDSK can help troubleshoot and repair file system errors.

However, since Windows is not bootable, you cannot run CHKDSK as usual. In this case, go to the Windows Recovery Environment (WinRE) to access the Command Prompt.

There are typically two ways to run CHKDSK when your PC won’t start normally:

Option 1. Force access Windows Recovery Mode using the Power button

Step 1. Press and hold the Power button for about 10 seconds to turn off the computer.

Step 2. Press the Power button again to turn it on. During startup, press and hold the Power button for 10 seconds to shut down your computer.

Step 3. Repeat this process three times.

When you see the message “Automatic Repair couldn’t repair your PC”, click Advanced options to enter WinRE.

Step 4. Navigate to Troubleshoot > Advanced options > Command Prompt.

Now, run the CHKDSK command to repair file system errors.

Once the errors are found and fixed, restart your computer and check if it boots normally.

Option 2. Use the Windows installation media

If you cannot access the recovery environment using the Power button, use a Windows installation media instead.

Step 1. On a working computer, insert a blank USB drive and create a Windows installation media.

Step 2. Insert the USB disk into the unbootable computer and restart it.

During startup, press the appropriate key, usually F12, F2, F10, or Esc,to enter the boot menu, then select the USB drive as the boot device.

Step 3. On the Windows Setup screen, click Next, and then click Repair your computer.

Step 4. Choose Troubleshoot > Advanced options > Command Prompt.

Now, execute the CHKDSK command to check and repair your drive.

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Check CHKDSK Logs

After running CHKDSK, reviewing the provided information is essential.

Note that the results may not always be visible on the screen, especially if the scan was automatic or the command window was closed.

Fortunately, the system retains CHKDSK logs, allowing you to confirm what errors were detected and whether they were successfully repaired.

Here is how to check CHKDSK logs:

Step 1. Type Event Viewer in the Windows search box and press Enter to open it.

Step 2. Expand Windows Logs. Then right-click Application and choose Filter Current Log.

Step 3. Expand the Event sources drop-down menu, then tick Chkdsk and Wininit, and click OK.

The events related to CHKDSK will be displayed, and you can review the details of each scan.

Part 4. Troubleshooting CHKDSK Errors

Although CHKDSK is effective for repairing disk errors and marking bad sectors, certain issues may prevent it from running correctly.

This section outlines some common CHKDSK errors and explains how to troubleshoot them.

CHKDSK Cannot Run Because the Volume Is in Use by Another Process

This error occurs when the drive you are trying to check is currently in use by Windows or another program.

Under this circumstance, there are two solutions.

Solution 1. Use the /x Parameter

If you are running CHKDSK on a non-system drive, use the /x parameter to forcibly dismount the drive.

In Command Prompt, type chkdsk drive letter: /f /r /x (replace the drive letter with the actual one) and press Enter. The error should not appear again.

However, the /x parameter does not work for the system drive, because when Windows is running, the system drive is in use. In this case, try the next solution.

Solution 2. Run CHKDSK on Next Restart

When you see the message saying that the volume is in use, there will usually be another prompt asking if you want to run CHKDSK the next time you restart the computer.

Type y and press Enter. The next time you restart, CHKDSK will run automatically before Windows loads to your desktop.

CHKDSK Is Not Available for RAW Drives

If the file system of a drive is corrupted or missing, Windows may recognize it as a RAW drive. CHKDSK cannot operate on RAW volumes, so you need to repair the drive before running CHKDSK.

In this case, the only solution is to format the disk.

Important: Recover Files From the RAW Drive Before Formatting

Since formatting will remove all files on the RAW drive and make free data recovery more difficult, you should recover any important data first.

MiniTool Power Data Recovery can scan and recover files from RAW drives easily. It is fully compatible with HDDs, SSDs, USB drives, SD cards, and other storage devices.

This data recovery software supports recovering up to 1 GB of files for free. Download and install it to give it a try.

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Solution – Format the Disk

After recovering your files, format the RAW drive in File Explorer to restore it to a normal state.

Step 1. In File Explorer, right-click your disk and choose Format.

Step 2. Specify the file system, volume label, and click Start.

Step 3. Click OK to begin. Once formatting is complete, your drive should return to normal, and CHKDSK should run on it without errors.

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CHKDSK an Unspecified Error Occurred

Sometimes CHKDSK fails without giving a clear reason, but only with an unspecified error. This can be caused by system file corruption, interference from other programs or drivers, and other issues.

In this case, run CHKDSK in Safe Mode or use system file repair tools like DISM and SFC.

Solution 1. Run CHKDSK in Safe Mode

Safe Mode is a diagnostic startup mode that loads only the essential drivers and services. By booting into this mode, you can ensure that CHKDSK runs without interference from third-party software or malware.

Here is a short video guide on how to boot into Safe Mode:

Step 1. Hold down the Shift key, and then click Start > Power > Restart.

Step 2. On the Choose an option screen, select Troubleshoot.

Step 3. Select Advanced options > Startup Settings > Restart.

Step 4. Press 4 to enable Safe Mode, or press 5 to enter Safe Mode with networking.

After entering Safe Mode, open Command Prompt as administrator and check if CHKDSK can run successfully. If it still fails, proceed to the next solution.

Solution 2. Run DISM & SFC

Corrupted or missing system files may prevent CHKDSK from running properly. In this case, using the DISM and SFC tools to detect and repair these files can resolve the issue.

Here is how to run DISM and SFC:

Step 1. Open Command Prompt as an administrator.

Step 2. Input the following command and press Enter:

DISM.exe /Online /Cleanup-image /Restorehealth

Step 3. After the DISM scan finishes, input sfc /scannow and press Enter.

When the SFC scan completes, if Windows reports that it found and repaired corrupted files, check whether CHKDSK runs without errors.

CHKDSK Cannot Open Volume for Direct Access

This error usually indicates that the drive is currently in use by other programs or has physical issues.

When this error occurs, you can use the chkntfs /x command to temporarily dismount the drive. This allows CHKDSK to run without the volume being locked. If this method fails, perform a clean boot to eliminate software conflicts.

Solution 1. Run Chkntfs to Bypass Volume Lock

Here is how to dismount the drive:

Step 1. Launch Command Prompt as an administrator.

Step 2. Input chkntfs /x drive letter: and press Enter. Replace the drive letter with the actual letter of your drive.

Step 3. Once the drive is dismounted, run CHKDSK again.

Solution 2. Run CHKDSK in a Clean Boot Environment

In a clean boot environment, Windows starts with a minimal set of drivers and programs. This helps identify if any software conflicts are blocking CHKDSK from running.

Step 1. Right-click Start and choose Run. Then type msconfig and press Enter.

Step 2. Go to the Services tab.

Step 3. Tick Hide all Microsoft services, and then click Disable all to disable all non-Microsoft services.

Step 4. Switch to the Startup tab, and click Open Task Manager.

Step 5. Select and disable all unnecessary enabled items. After that, restart your computer and check if CHKDSK runs successfully.

If CHKDSK works properly in a clean boot, it means that certain programs or services are interfering with the disk scan.

To find the culprit, gradually re-enable startup programs and services until the error occurs again.

Windows Cannot Run Disk Checking on This Volume Because It Is Write Protected

The write protection error usually occurs when a drive is set to read-only mode. This can happen in two ways:

• Physical write protection. Many SD cards have a physical lock switch on the side. When the switch is in the Locked position, the card is write-protected.
• Software-level write protection. The drive’s attribute is set to read-only.

In these cases, you need to remove the write protection of the drive.

Solution – Remove the Write Protection

First, check if your storage device has a physical lock switch (commonly on SD cards). If it does, make sure the switch is set to the Unlocked position.

If this does not apply to your situation or does not resolve the issue, follow the steps below to remove the read-only attribute from the drive.

Step 1. Open Command Prompt as administrator.

Step 2. Type the following commands, and press Enter after each one:

• diskpart
• list disk
• select disk # (replace # with the target disk number)
• attributes disk clear readonly

After clearing the read-only attribute, CHKDSK should run successfully.

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Part 5. CHKDSK Performance Considerations

When running CHKDSK, the time it takes to complete can vary significantly depending on several factors. The primary factors include the size of your drive, the number of files, the disk type, and the CHKDSK parameters specified.

Understanding these factors is important so you can take appropriate measures to avoid interrupting your workflow.

This section explains what affects CHKDSK runtime in detail and provides practical tips to optimize CHKDSK performance, especially for large drives.

Factors Affecting CHKDSK Runtime

The time CHKDSK takes to complete typically depends on several factors, including:

Disk size

Larger disks have more sectors and can hold more files. Thus, CHKDSK has to scan a great number of sectors and examine more file entries.

Consequently, scanning larger drives generally takes more time.

File system type

The type of file system also affects the scanning time. Different file systems, such as NTFS, FAT32, or exFAT, have varying levels of complexity and internal structures.

While there is no absolute rule, NTFS generally requires more time than FAT32 due to its more complex structure.

Fragmentation level

Disk fragmentation affects scanning speed. Over time, as files are created, deleted, and modified, file fragments may be scattered across the disk rather than stored contiguously. This forces CHKDSK to access multiple locations, thereby increasing scan time.

Disk type

The type of storage device also influences CHKDSK performance. Because solid-state drives (SSDs) have no moving parts, they can read and write data much faster than hard disk drives (HDDs).

As a result, CHKDSK generally completes more quickly on SSDs, though the difference may be less noticeable on small disks or when scanning a single partition.

CHKDSK parameter

Which CHKDSK parameter specified also affects how long it takes to run. For example:

• Using /r to check for bad sectors takes a long time because every sector is checked.
• Using /i (NTFS only) performs a less thorough check of index entries, so it can reduce the time needed to run CHKDSK.
• Using /c (NTFS only) skips checking cycles in the folder structure, which also shortens the scan time.

As explained, many factors can affect how long a disk scan takes, and CHKDSK can sometimes take a long time, especially on large drives.

So, I would like to introduce some tips to minimize the impact on your workflow or files.

How to Minimize Impact on Workflow

Run CHKDSK during non-business hours

CHKDSK can take a long time on large drives or when checking for bad sectors, so it is best to run it when your computer is idle or during non-business hours.

Use appropriate parameters

When running CHKDSK, using the right parameters can save time and protect your drive. For example, you may consider:

• Always start with /f to fix file system errors before doing a full /r scan.
• On NTFS drives, use /i to skip index checks and /c to skip folder cycle checks, which speeds up scanning.
• Avoid using /r frequently on SSDs, as it increases write/erase cycles and may slightly reduce the SSD’s lifespan.

Avoid stopping CHKDSK midway

Although interrupting CHKDSK usually won’t make your drive more corrupt than before, it is still not recommended. Interruptions can force a rescan later, which will waste a lot of time.

Back up data

CHKDSK usually does not cause data loss, but there are exceptions.

For example, repairing FAT file systems can modify the file allocation table and sometimes result in lost data.

When this happens, CHKDSK may display a confirmation message similar to the following:

10 lost allocation units found in 3 chains. Convert lost chains to files?

If you press Y, Windows will save each lost chain in the root directory as a file named File<nnnn>.chk. After CHKDSK finishes, you will be able to check these files for any recoverable data.

In summary, while CHKDSK is designed to repair file system errors, data loss can sometimes occur when running it. Therefore, make sure to back up your important files to an external drive or cloud storage before scanning.

For backing up large amounts of data, MiniTool ShadowMaker is recommended. It can back up files, folders, partitions, and entire disks for free for 30 days.

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Part 6. CHKDSK Alternative – MiniTool Partition Wizard

As mentioned above, while CHKDSK is a useful tool for checking and repairing file system errors, running it through Command Prompt can be complex and may result in unexpected errors.

If you prefer a more user-friendly method to repair disk issues, MiniTool Partition Wizard is worth trying.

Its built-in Check File System feature performs the same function as CHKDSK but offers a clear graphical interface that makes the process much easier.

This function is completely free to use, so you can download and install the tool to give it a try.

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Step 1. Launch MiniTool Partition Wizard to enter its main interface. Select the disk partition you want to check, then scroll down the left menu bar to click Check File System.

Step 2. Select Check only or Check & fix detected errors per your needs, and then click Start.

Once the scan is complete, review the results to see whether any errors were found or if they have been fixed.

How CHKDSK Differs From MiniTool Partition Wizard

Both CHKDSK and MiniTool Partition Wizard can be used to detect file system errors. The following table compares their differences.

In summary, while CHKDSK offers more flexible command-line options, MiniTool Partition Wizard provides a more user-friendly and intuitive interface for checking and repairing disks. You can choose the one you prefer.

Part 7. CHKDSK vs. DISM vs. SFC

In addition to CHKDSK, Windows offers several other tools for troubleshooting system errors, and DISM and SFC are two commonly used ones.

Many users often confuse CHKDSK, DISM, and SFC, likely because their functions sound similar. For example, here is an actual scenario:

Is there any difference between SFC SCANNOW and CHKDSK /F? What kind of situations would they be used for? Do they overlap? Is there an order in which to use first? Thanks.reddit.com

To clear up this confusion, it is necessary to analyze how these tools differ.

CHKDSK

This tool is a disk-based tool that focuses on checking and repairing issues at the disk level. It scans the file system for errors and locates bad sectors.

CHKDSK is primarily used in cases where disk issues are suspected.

DISM

DISM, short for Deployment Image Servicing and Management, is a system-based tool that focuses on repairing the Windows system image. During this process, it uses Windows Update as the source to provide the necessary files.

Overall, DISM is used when the system image is corrupted or when Windows features fail to work correctly.

SFC

SFC, short for System File Checker, is a system-based tool designed to scan for and repair individual missing or corrupted system files.

DISM and SFC are commonly used when system files are missing or corrupted, when some Windows features stop working correctly, or when Windows becomes unresponsive.

The system image that DISM repairs is the foundation for many system components. If the image is corrupted, SFC cannot find clean copies of system files to restore. For this reason, Microsoft recommends running DISM first, especially when dealing with serious system corruption.

Overall, CHKDSK focuses on disk issues, while DISM and SFC work on system files and the Windows image. For a clear comparison of these three tools, check the table below.

Part 8. Conclusion

To sum up, this guide explains what CHKDSK is, its functions, and how to use it with key parameters to check and repair disk errors on Windows.

It also outlines common CHKDSK errors along with practical solutions, and offers several performance tips to reduce runtime impact.

Finally, it compares CHKDSK with DISM and SFC tools to help you choose the right utility when running into problems on Windows.

If you have used MiniTool software to recover files, manage partitions, or back up data, and run into any issues during the process, contact the support team at [email protected]. We will be happy to help you out.

Part 9. CHKDSK FAQ