I actually just set up an identical dell tower to use as backup. I figure I can just swap drives and edit fstab if there's a failure in the main rig.

Servers on the otherhand make me a bit nervous. If you're running in raid 5 or 6, rebuild can take weeks depending on the the size of the virtual drive, and that's a lot of stress on the drives. Even rebuilding a raid 10 can take days — it's usually faster to run in raid zero and use regular rsyncs, and swap if shit gets borked.