I was setting up a NAS box using FreeNas and received what looks like a possible hard drive error. My drives are new so I need to check for a drive problem. They are Western Digital Reds. I thought I had a utility disk from other WD drives I have but guess not. I looked at the WD site and the only utility they list for my drives is a data clone utility "Acronis True Image WD Edition." I don't think that will do. So my question, what is a good free bootable hard drive tester? Thanks