Run ScanDisk (commonly the chkdsk utility on Windows) to verify and repair file system and disk integrity errors affecting drive reliability.
What ScanDisk Is and When to Use It
ScanDisk is a long-standing diagnostic tool that checks a storage device for file system corruption, bad sectors, and metadata inconsistencies. On modern Windows systems, the equivalent and actively maintained command is chkdsk, exposed through the graphical Check Disk utility and the command-line chkdsk.exe. You should run it when you observe frequent hangs, file corruption, unexpected system crashes, or non-ejectable media removal messages. It is most effective as a read-only scan first, followed by repairs when necessary and safe.
How ScanDisk / chkdsk Works Under the Hood
ScanDisk and chkdsk validate file system structures by examining the file system metadata—file allocation tables (FAT), master file table (MFT) on NTFS, and inode maps on other file systems—and cross-checking directory entries with physical disk locations. The tool can operate in multiple modes:
- Basic read-only scan without repairs
- Automatic correction of logical file system errors
- Surface scan for bad sectors and marking them as unusable
These operations are I/O intensive and can take minutes to many hours, depending on disk capacity, number of files, interface speed, and extent of errors.
How to Run ScanDisk on Windows (Step-by-Step)
Graphical Method (Recommended for Most Users)
This approach uses the Check Disk GUI and is the safest way to initiate a scan without typing commands.
- Open File Explorer and right-click the target drive under This PC or Computer.
- Select Properties > Tools > Check.
- Choose Scan drive (or Scan) and wait for the progress to complete.
Command-Line Method (chkdsk)
Use chkdsk in an elevated Command Prompt or PowerShell when you need specific switches or cannot access the GUI. Common switches include:
- /f — Fixes errors on the disk (requires write access).
- /r — Locates bad sectors and recovers readable data (implies /f).
- /x — Forces the volume to dismount first if necessary.
- /i — Performs a less vigorous check of index entries (NTFS only).
Example: chkdsk C: /f /r. If the target drive is in use, Windows will prompt you to schedule the scan on the next restart.
Safety, Performance, and Limitations
Running a read-only scan is generally safe and has minimal risk. However, allowing automatic repairs—especially with /f or /r—can result in data loss if the disk has severe corruption or impending hardware failure. Before permitting repairs:
- Ensure you have recent, restorable backups.
- Close all applications that hold open handles to the target drive.
- Prefer a read-only scan first to assess the scope of issues.
Note that chkdsk cannot repair encrypted files without access to your decryption keys, and it does not recover user files—only attempts to fix file system structures so the OS can access them again.
When ScanDisk / chkdsk Is Not Enough
For physical media problems such as clicking sounds, intermittent detection, or consistently failing S.M.A.R.T. indications, ScanDisk may report uncorrectable errors. In these cases:
- Back up data immediately.
- Use manufacturer-specific S.M.A.R.T. and diagnostic tools for further assessment.
- Consider professional data recovery services for critical data on failing drives.
SSD devices benefit from TRIM and wear-leveling; chkdsk can still fix file system errors but cannot realign heavily fragmented or degraded NAND blocks.
Practical Best Practices and Alternatives
Use ScanDisk / chkdsk as part of a broader storage maintenance routine rather than a one-time fix. Combine regular scans with proactive monitoring:
| Action | Recommended Frequency | Tool |
|---|---|---|
| Read-only integrity check | Monthly or after system instability | chkdsk C: without switches or GUI scan |
| Surface and bad-sector scan | Quarterly or when experiencing read errors | chkdsk C: /r or vendor utilities |
| File system and metadata backup | Weekly or continuously | robocopy, File History, or imaging solutions |
| S.M.A.R.T. health monitoring | Continuous via OS and periodic review | Windows Management Instrumentation, vendor tools |
Summary
To run ScanDisk effectively and safely, use the graphical Check Disk tool for routine checks, and employ chkdsk with appropriate switches for advanced scenarios. Prioritize backups, start with read-only scans, reserve repairs for when you have verified media health, and escalate to manufacturer tools or professional recovery when hardware failure signs appear. These practices help maintain file system integrity and prolong reliable storage lifespan.