I would like to direct you to
http://en.wikipedia.org/wiki/RAID#Hardware_RAID
A hardware RAID controller should be used in a server, OS doesnt matter. Failure of one drive means the other takes over, im talking about mirroring, not stripping.
RAID 1: Mirrored Set (2 disks minimum) without parity: provides fault tolerance from disk errors and single disk failure. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing. Array continues to operate so long as at least one drive is functioning.
And I do apologise if anything i have said is wrong, i was under the impression that RAID can be controlled separate from the OS, at least I know my RAID controller is independant