My 4TB OWC Mercury Pro suddenly unmounted about 600GB into my 2.02TB initial time machine backup. This brand new drive had flawlessly transferred 1.2TB from my Mac Pro via FireWire, and then transferred that same 1.2TB via USB 3 onto the iMac. It was plugged into the same port for the Time Machine backup. After that incident I erased the drive, switched USB ports and began the backup again. I was away for over six hours, and when I came back it appeared that the backup had completed successfully this time... but I don't know for sure if it didn't unmount while I was away and somehow remount and appear to successfully finish. In any case the event was highly disturbing and I'm unsure about whether I should trust this drive, or my iMac for that matter (could it have faulty USB ports?) What would you do?