I know TechTool Pro can recover files, test performance and stuff like that but it seems to do a lot of processing in the background and take writes a lot of stuff to disk. So, in English, what's it actually doing and is it really worth it. I backup my disk very regularly and from past experience when things go wrong with disks, they really go wrong and it's generally back to backup time. So basically, can someone tell me why I should keep it running?