It seems tempting to put everything on a single volume, but what happens if you need to rebuild that volume? You put all your data at risk. I have been running a 16 Disk RAID5 volume in production for a number of months now. We are going to modify this so it's two RAID10 volumes. The reason is simply to ensure that if we need to run a volume check or we loose a volume or it has to be rebuilt, we don't loose our entire operation.