How to Fix a Bad Cluster on a Hard Drive

In most cases, lost clusters are nothing more than an annoyance. Fixing them can be a relatively straight forward process though it can seem scary. Most importantly, a full hard drive scan can take a very long time on a big hard drive.

Using CHKDSK to Fix Your Hard Drive Issues

Step

Understand your problem. In a Windows based file system, a cluster is a block of storage space that is not listed as free, but is not assigned to any file either. In other words, the file system has marked the cluster to not be overwritten, but it doesn't know why. This does not necessarily indicate any problems with the hard drive itself. Usually, lost or bad clusters are the result of improper program terminations due to things like power loss, or shutting off a computer without closing the applications first.

Step

Open a command prompt or DOS prompt. Depending on which version of Windows you are using there are multiple ways to run the CHKDSK utility. The method that works across most versions is to run it via the command line.

Step

Type "chkdsk /r" in your command prompt window. This tells the computer to run the CHKDSK utility and to repair any errors that it finds. Your computer may need to be rebooted in order to run the chkdsk utility. The utility can take a very long time to run (from several minutes, to hours).

Step

Wait for the utility to finish. Unless you begin seeing errors on the screen right away, it is probably in your best interest to go do something else while your computer checks the drive. The process can take hours, so there is not need to sit and stare at the screen.

Step

Reboot. After the utility has completed, reboot your system to start the operating system normally. Your lost clusters will be saved as files named with the convention: file####.chk

Step

Usually the data in such files is worthless. However, you may be able to analyze the files and recover some data if it is critical.