Seeking some advice. Is there any reason to not put a backup drive in one of the extra bays in the Mac Pro, rather than externally? Also what's a good rule of thumb for a backup drive's capacity vs. the main drive? Thanks. EDIT: Read about about having off-site drives in case of fire to answer the first Q. So I might as well be specific about my needs... For audio recording, I'm looking at: OS: SSD ~100 GB Record drive: 1 TB Samples / Personal Media: 2 TB split into 2. I am trying to devise an effective backup solution but I'm just learning about RAID, still unsure what would be the best path.