[gentoo-user] RAID with mixed drive sizes

[Benoit St-Pierre]

I'm in the planning stages of setting up a file server and am considering
using RAID.

My concern is that my drive sizes are mixed. I have two 500GB SATA drives, a
320GB IDE and a 250GB IDE.

I would like to set these up so that the maximum amount of disk space is
usable, but still be able to recover from any one drive failing. I would
also like to be able to add drives of any size as easily as possible.

Is it possible to split each disk into a bunch of 10GB partitions, giving me
157 partitions in total, and specifying that I want to have 50 partitions
worth of parity info so that if any 50 partitions go bad (ie: one of the
500GB disks) the RAID can recover? Adding/replacing would be simple if I can
change the amount of parity info to keep, but I don't know if this is
actually possible. It looks as though spares need to be explicitly given so,
if a disk with lots of spares goes down, it's not going to work.

Another option I see is if I create 4x 250GB partitions (one on each drive)
in one RAID5 array, 3x 70GB partitions (on the 3 larger drives) in another
RAID5 array, and two 120GB in a RAID1 array. The RAID1 array reduces my
total available disk space a bit, which is less than ideal and
adding/replacing disks would be more of a headache.

I remember reading something about using LVM and RAID to achieve this, but
everything I've found has been for identical drives.

Any suggestions?