How many Xserve RAIDs will I need?
The minimum number of Xserve RAIDs your SAN will need is determined more by your bandwidth than storage requirements. Each Xserve RAID controller can provide real world 60MBps of sustained data. Each Xserve RAID has two controllers. So a single stream of 1080 24p, 10-bit, at 110MBps, requires two controllers, or a single Xserve RAID.