I am having odd issues with the second HDD in my 2011 Mini Server. I ordered the upgraded version (7200 RPM 750 GB) and I was quite pleased to find WD Scorpio Black drives. I replaced the top HDD with an OCZ Vertex 3, which has been working without any issues. Unfortunately I cannot say the same for the HDD. I have this drive formatted in exFAT, which has not caused me any issues before and I use it for a lot of other disks. The other HDD that I took out is now sitting in an OWC enclosure and I use it to back up the HDD left in the mini. It is also formatted with exFAT and does not give me any issues. Basically the partition on the HDD left in the server just disappears every couple of days. I can run Verify Disk in Disk Utility and it will repair it with no data loss, but this is annoying. As I said, the HDD sitting in the external enclosure does not experience this issue. Has anyone seen something similar?