On Mon, 20 Jun 2011, Dave Burgess wrote:
I'm trying something a little complicated.
I've built a 2Gig raid0 array to boot from.  I'm using all four disks 
as raid elements (two live, two as spares).  [...]
After that, I set the rest of the disks up in a raid5 config.
You could also consider having a separate 2GB boot partition on each 
disk, without glueing them together into a RAID0.  In normal use, 
you'd keep them all identical, using rsync or dump|load or something, 
but you would also have the ability to test upgrades by installing on 
only one of the multiple boot partitions.  (I do this with a two-disk 
system, with a small boot partition on each disk, and a large RAID0 
over "the rest" of both disks.)
--apb (Alan Barrett)