I've got a lot of servers with the root filesystem (including /boot) on a RAID-1 array. For years I've had systems configured such that if one drive fails then the other can boot the system (although in the case of IDE if drive 0 fails then the other drive would have to be changed to the other cable before booting). http://etbe.coker.com.au/2012/04/17/zfs-btrfs-cheap-servers/ Now I'm considering the case of a reasonable size ZFS server. Would it work to have an 8-disk mirror for the root filesystem? I'll probably put /var on ZFS so the root filesystem won't need to be particularly big. In terms of wasting space a 10G root filesystem mirrored across all disks isn't a big deal when you have 3TB disks. It seems that the ability to boot from any disk and having a symmetric layout provide more benefit than saving maybe 60G of raw disk capacity. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/