Bad sectors get reallocated automatically, so you might not find any with testing. You need to see how many have been reallocated. SMART should already be enabled, so maximize your term window and type: smartctl -a /dev/sdb That will show the reallocated sector count, as well as power on hours, and temps, etc. Do that for each drive. If its attached to a raid controller, you have to take additional steps as found on google. If there are any reallocated sectors, you might want to think about replacing it. I have a customer with a failing drive in a server that causes it to freeze from time to time as it develops new bad sectors. I'm replacing it this weekend...