In our shop we're faithfully using RAID in all our workstations, probably just because that seems to be the way it ought to be done. I'm talking about workstations for scientific simulations, using the onboard RAID chips.
But I've heard a lot of RAID horror stories. Stackoverflow itself has had an outage caused indirectly by RAID controller.
RAID protects you against a very narrow type of failure - physical disk failure - but at the same time it also introduces extra points of failure. There can be problems with the RAID controller, and there often are. In our shop at least, it seems that RAID controllers fail at least as often as disks themselves. You can also easily mess something up with the process of swapping a faulty drive.
When is RAID worth the trouble? Don't you get a better return on investment by adding more redundancy to your backup solutions? Which type of RAID is better or worse in this regard?
Edit: I've changed the title from the original "Is RAID worth the trouble?", so it sounds less negative