SMART is a set of tools some Hard Drives come with to monitor there health. I got a new HD off Ebay and was having issues and SMART helped me save myself some headache by confirming it was a bad drive.
In my case all i need to do was see the output of:
said Failed, end of story!
--check if drive has SMART capabilites
--if supported but disabled
--to find estimated times to run tests
--to run the long test, the best of course
--For detailed info on IDE drive
To check mounted disks /dev/XXX use: