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Check a Drive for Bad Sectors with Chkdsk

The online scan that needs no restart, the spotfix for small damage, and the full surface test for a drive you already suspect.

by@guidox updated:10/31/26 time:45 min level:Intermediate tested on:Windows 11 24H2 works on:Windows 10, Windows 11 tools:Command Prompt as administrator, PowerShell
TL;DR

Start with **chkdsk C: /scan**, repair what it found with `chkdsk C: /spotfix`, and schedule `/f /r /x` at boot only when you expect physical damage.

Before you start

Requirements

  • Command Prompt as administrator
  • Free time for the surface test
  • Thirty minutes
Step by step

Instructions

01

Run the read-only scan first

The scan checks the file system while Windows keeps running. It locks nothing, changes nothing and prints a verdict at the end.

chkdsk C: /scan
02

Read the verdict, not the prose

Windows has scanned the file system and found no problems is the pass. Any other wording names the stage that failed, and that name is what tells you whether the damage is structural or only a dirty bit.

03

Repair small damage without a reboot

Spotfix repairs the problems the scan recorded, online. It is the fast path and it leaves the volume mounted.

chkdsk C: /spotfix
tipIf the fix list is large, the tool schedules the work for the next start instead of forcing it now.
04

Schedule the full surface test

The r switch reads every sector, f repairs file system errors and x forces the volume to be dismounted. This is the only mode that finds physically unreadable areas, and it runs before Windows starts.

chkdsk C: /f /r /x
⚠ warningHours on a large mechanical disk, and the machine must not lose power during it. Laptops need the charger connected.
05

Confirm it actually ran

The result is written to the Application log as one long message from Wininit. Searching it is faster than watching the boot screen.

Get-WinEvent -FilterHashtable @{LogName='Application'; ProviderName='Microsoft-Windows-Wininit'} -MaxEvents 3 | Select-Object -ExpandProperty Message
06

Check the drive, not only the file system

A file system that keeps needing repair is a symptom. Health status and reallocated sectors tell you whether the hardware is compensating for failing areas.

Get-PhysicalDisk | Select-Object FriendlyName,MediaType,HealthStatus,OperationalStatus
tipTwo repairs within a month on the same drive means replace it. The next failure usually costs data.
Troubleshooting

Common issues

Cannot lock current drive

The volume is in use by Windows. Answer Y to schedule the check for the next restart.

/r has been running for hours

Expected on mechanical drives. Past roughly ten hours per terabyte the surface itself is failing, not the tool.

The scan reports NTFS is RAW

The partition table or boot sector is damaged. Copy the data off first; repairing can remove what is left.

Bad clusters were replaced

Back up immediately. Replaced clusters mean data was already lost, and more will follow.

FAQ

Frequently asked

Is chkdsk safe on an SSD?

The scan and spotfix are. The r switch writes every sector and adds wear, so read SMART health instead when the drive looks fine.

Does it recover files?

It fixes the file system around them, not their contents. Deleted files need a recovery tool.

How to undo this

Nothing to undo: scan and spotfix only touch file system metadata. A scheduled full check can be cancelled with chkntfs /x C: before the reboot.

Changelog · 1 entry
  1. 2026-10-31
    First version
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