I've setup a random 230GB disk as root with all important data on zfs.
This is one of two remote replicas (via synthing) so not using mirroring or other in-machine redundancy. Picked zfs so I could rely on its data checksumming and trivial adding of additional disks into a pool. The other replica is setup similarly except for (3* 2TB instead of the 8TB).
I have an issue getting zfs initialised on a third machine, and it would be even better to be able to boot from zfs, but, not going to let that stop me from being very happy with the result on these two :)
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
onyx0 2.31T 4.71T 27K /onyx0
onyx0/media 2.31T 4.71T 2.31T /home/media
onyx1 7.78T 2.75T 23K /onyx1
onyx1/foo 7.78T 2.75T 7.78T /home/media/foo
# ag wd.\*GB /var/run/dmesg.boot
204:wd0: 232 GB, 484521 cyl, 16 head, 63 sec, 512 bytes/sect x 488397168 sectors
210:wd1: 7452 GB, 15504021 cyl, 16 head, 63 sec, 512 bytes/sect x 15628053168 sectors
216:wd2: 5589 GB, 11628021 cyl, 16 head, 63 sec, 512 bytes/sect x 11721045168 sectors
222:wd3: 5589 GB, 11628021 cyl, 16 head, 63 sec, 512 bytes/sect x 11721045168 sectors