I am thinking of doing this: Tray 1: SSD boot/apps Tray 2: 1TB storage drive External 1 FW800: 1TB storage drive And then mirroring the TB drives with a OS X software Raid 1. But, if one drive crashes, is the other drive instantly usable? How do you separate or recover the "mirrored" drive in a Raid 1? Also, can you do a Raid 1 with a drive on an SATA, and then a FW800 with such different transfer speeds, will the FW800 drive be able to write as fast as the SATA one, or will the SATA one have to slow down? What is the best way to have an internal drive in the mac pro, and then have it real-time mirrored on an external? Or is this not possible.