[K12OSN] why RAID?

[Michael Wescott]

> why is it so important to get RAID set up?  Why not just
> have a cron job that makes a copy of /home or any other
> important directories?

RAID levels 1 and 5 provide a sufficient redundancy that you
can lose a disk without losing data. There are, of course,
other tradeoffs; the redundancy comes at the price of additional
disks and a performance impact on writes. There is also a gain in
read performance.

But disk failures aren't the only way to lose data. A RAID
decreases the probability that a hardware failure will cause
data loss, but it has no impact on users or administrators
deleting or overwriting a file. So having a RAID setup does
not eliminate the need for doing periodic backups.

-- 
	Mike Wescott
	Wescott_Mike at EMC.COM