ZFS NAS configuration question

[Dan Naumov]

Hey

I am not entirely sure if this question belongs here or to another
list, so feel free to direct me elsewhere :)

Anyways, I am trying to figure out the best way to configure a NAS
system I will soon get my hands on, it's a Tranquil BBS2 (
http://www.tranquilpc-shop.co.uk/acatalog/BAREBONE_SERVERS.html ).
which has 5 SATA ports. Due to budget constraints, I have to start
small, either a single 1,5 TB drive or at most, a small 500 GB system
drive + a 1,5 TB drive to get started with ZFS. What I am looking for
is a configuration setup that would offer maximum possible storage,
while having at least _some_ redundancy and having the possibility to
grow the storage pool without having to reload the entire setup.

Using ZFS root right now seems to involve a fair bit of trickery (you
need to make an .ISO snapshot of -STABLE, burn it, boot from it,
install from within a fixit environment, boot into your ZFS root and
then make and install world again to fix the permissions). To top that
off, even when/if you do it right, not your entire disk goes to ZFS
anyway, because you still do need a swap and a /boot to be non-ZFS, so
you will have to install ZFS onto a slice and not the entire disk and
even SUN discourages to do that. Additionally, there seems to be at
least one reported case of a system failing to boot after having done
installworld on a ZFS root: the installworld process removes the old
libc, tries to install a new one and due to failing to apply some
flags to it which ZFS doesn't support, leave it uninstall, leaving the
system in an unusable state. This can be worked around, but gotchas
like this and the amount of work involved in getting the whole thing
running make me really lean towards having a smaller traditional UFS2
system disk for FreeBSD itself.

So, this leaves me with 1 SATA port used for a FreeBSD disk and 4 SATA
ports available for tinketing with ZFS. What would make the most sense
if I am starting with 1 disk for ZFS and eventually plan on having 4
and want to maximise storage, yet have SOME redundancy in case of a
disk failure? Am I stuck with 2 x 2 disk mirrors or is there some 3+1
configuration possible?

Sincerely,
- Dan Naumov