Apple's One Rack Wonder - MacStories

The Xserve RAID isn’t as deep as the Xserve, but at 3U (about 5.25 inches) in height and weighing in at nearly 100 pounds when filled with hard drives, it is a solid piece of hardware.
To connect to the Xserve, the Xserve RAID supported dual 2 Gb Fibre Channels. That meant the two machines could talk to each other at speeds up to 400 MBps.
From the beginning, the Xserve RAID had redundant power and cooling systems, something that wouldn’t come to the server for several revisions.