Hi! I just bought a San Mobile Stor external RAID box. It's configured as RAID 0. I've got two Hitachi 750 GB hd's in it. It's connected to my 15" mbp via eSATA (Sonnet Tempo). It was working fine all day yesterday, then I had three incidents today. First, I was importing a movie from my camcorder when the bottom hard disk bay started beeping and the Mobile Stor LCD said it was bad. I turned it off, waited 15 seconds, and turned it back on. It came fine and the LCD said the bottom HD was OK. Second incident was for the same hard disk, but the alarm came up when I rebooted my mbp. Turned the Mobile Stor off, removed the bottom tray, and put it back in. Turned the RAID box on again and it shows OK. The third incident was after another reboot of the mbp. But this time it's the top hard disk drive that's sending out the alarm. Cycling of the Mobile Stor "fixed" it. Since the Mobile Stor, my Sonnet Tempo expresscard, and the hard drives are all new, I don't know which one is the most likely culprit. I would like to eliminate the HD's from the suspects list by doing a surface scan on it. The hard disk utility in the Leo install DVD does not do external HD's. The OSX Disk Utility's First Aid only checks the file structure. I was wondering if someone can recommend a freeware HD surface scanner. Techtool looks good, but seems like overkill for what I need and costs too much. So any suggestions for a freeware, or at least, one that's cheaper than Techtool Pro?