Lost cluster
Updated: 04/26/2017 by Computer Hope
A lost cluster is a segment of data that is corrupted or missing, causing the computer to register data as used when it's not. When getting lost cluster hard drive messages, it is often a strong indication that the hard drive is failing. If you're running Microsoft Windows and are still able to get into Windows back up all critical data and try running ScanDisk on the computer, to mark these clusters as bad. If you are getting lost or missing cluster messages during a format, we recommend you replace the hard drive.