[DM-MUG] backups, external FW drives, and concatenated RAID

[kristau]

On 3/27/07, Ray Bowler <rbowler at mchsi.com> wrote:
> I'm trying to remember but don't the two drives in the RAID have to
> be the same size?

That depends on the RAID configuration, but in general you will end up
using the smaller of the two capacities.  Here's a break down:

RAID 0, striping or concatenating.  Capacities are additive.  EG: 200
GB + 300 GB = 500 GB available.

RAID 1, mirroring.  Size of the smallest drive is the capacity of the
volume.  EG: You can't duplicate the 300 GB drive to the 200 GB drive,
but you can go the other way around.

RAID 5, three or more drives made redundant.  Portions of the data are
duplicated across the three drives such that you can lose any one
drive and not lose data.  Each drive will only use the space equal to
the smallest drive, but the drive space is additive as add drives.
EG: 100 GB + 200 GB + 300 GB = 200 GB volume.  Each drive only uses
100 GB and the total volume space is equal to (number of drives) *
(capacity on each drive) - (capacity of one drive).

Hope that wasn't too confusing!  My head spins a bit when I talk about RAID. . .

-- 
Tired programmer
Coding late into the night
The core dump follows

My GNUPG public key is available at http://www.kristau.net/public_key.asc