Remember to take backups *anyhow*. That way, if the RAID controller
dumps cow manure on all the sectors, you won't be saying "Oh, SH*T".
Linux software RAID doesn't need a controller ;)
But yes, backups should be done anyways.
IMHO, RAID is good, harddisks are less reliable than the linux kernel,
the linux RAID layer, and reiserfs.
Also, note that there exist buggy RAID controllers, where if you are
doing
mirroring to 2 disks, and they develop bad blocks at different locations,
you can trash the mirror by resynchronizing (basically, you swap out one
of
the bad disks, re-sync, it progresses as far as the bad block on the
source
for the mirror, and dies).
Linux RAID has a special option for that : you can trigger a check, which
will re-read the entire disks and, if a read error occurs, re-write the
failing sector with good data from the other drives in the RAID. The drive
with the bad sector will then remap it to another sector.
