Cheapest way to backup data

[jarod-ajLrJawYSntWk0Htik3J/w at public.gmane.org (Jarod Wilson)]

On Sun, 2009-02-22 at 13:11 -0600, Jack Coats wrote:
> Other raid levels are redundant, raid5 has the parity drive
> distributed across the various
> drives (that is why it requires a minimum of 3 drives, and more drives
> reduces 'loss' of storage space).
> Raid 6 is really raid6 with a hot spare as I understand it. (and
> depending on the controller/vendor you can have multiple hot spares).

I think you meant "raid 6 is really raid 5 with a hot spare", but that's
also incorrect.

RAID6 is very similar to RAID5, but the additional disk is NOT a hot
spare, its so the array can write an additional parity bit for every
data stripe. You need at least 4 disks, and get the capacity of only (n
- 2), but in theory, the array can survive the failure of any 2 disks in
the array.

-- 
Jarod Wilson
jarod-ajLrJawYSntWk0Htik3J/w at public.gmane.org