How To: Check for Bad Sectors on USB Flash Drive

This how to tutorial describes a simple way to check for bad sectors on a USB flash drive. The instructions below will also fix any bad sectors, if possible, during the scanning process.

A bad sector on a flash drive is a portion of memory on the flash drive which cannot be accessed, written to, or read from and therefore cannot be used. A bad sector on a flash drive sounds easy enough to diagnose, but it’s important to know there are two types of bad sectors: hard and soft.

Physical damage to a USB flash drive will create a hard bad sector. A hard bad sector cannot be repaired or fixed and is typically induced from physical abuse. A good example: leaving a flash drive in your pocket and it went through the wash, or the device was dropped and hit the ground is such a way, physical damage happened to the memory.

A soft bad sector on a flash drive are memory logic problems. A soft bad sector can occur from a software or data error during the write process. In lower quality flash drives, it is possible the incorrect firmware was written into the USB controller ROM and thus creates instability via soft bad sectors.

Bad sectors cannot be repaired; however soft bad sectors can be repaired.

The soft bad sectors can be fixed by using the CHKDSK utility in the Windows operating system. This same utility will also flag any hard bad sectors not to be used again, and of course not repaired.

Some signs of a bad sector on a flash drive include:

• Cannot read a file on the flash drive
• A file location is no longer available
• Unable to format the USB flash drive
• A disk read error occurs during operation

In our opinion, run the check disk one time to see if your issue is resolved, but if subsequent scans are required, we recommend discarding the flash drive to avoid further issues.

Running the chkdsk scan is really easy:

Insert flash drive to computer

Using Windows Explorer navigate to the drive letter

In the Explorer window type cmd and press enter

Once inside the command line utility type chkdsk d: /f /r /x and click Enter. NOTE: *The letter d represents the drive letter of the flash drive.

• The /f parameter tells CHKDSK to fix any errors it finds.
• The /r parameter tells Windows to repair/restore bad sectors (if possible).
• The /x parameter unmounts any “handles” to the drive or said another way, this step will not allow any other resource to access the flash drive during the scan.

The process will take a few seconds up to several minutes based on the GB capacity of your flash drive.

Once done, Windows will generate a report for you to determine if the USB flash drive should be used or discarded. If a drive has a bad sector it’s not the end of the world and means the USB stick should be thrown away (preferably e-recycled). What you don’t want, is an increasing number of bad sectors over time. If you find one or two bad sectors on the drive, we suggest scanning the drive a second time about a month after the first scan and compare if the bad secort count remained the same or increased.