If he is running a "array" of drives that are striped with parity such as raid 5 or 6 why would losing one drive in the array matter.
Losing one drive should not be a show stopper. Just buy another drive and hot swap out the bad drive for the new one.
If he lost a raid controller then that means the data on those drives are going to be worthless and data will need to be restored from backups.
If his raid controller is going bad and he wants to move the data to another array since he only has a single raid controller then that would make sense.