Disk configuration recommendations

[Steve Bertrand]

Hi everyone,

We've just built a new network storage box that will replace an existing 
unit. The device is purely for storing a hot backup of server images.

The motherboard has four SATA ports, which I have connected to four 
500GB SATA drives.

I had full intentions on using either GEOM or ZFS (I'm just reading up 
on the latter now) to span the drives together (I don't care about 
redundancy on this unit).

I did not realize until yesterday that the motherboard my colleague went 
with has onboard RAID.

What I'm looking for are opinions on a solution to make this box as 
resilient as possible for the long term (eg: if the motherboard dies, it 
would be nice to drop the disks into another box).

Do you have any recommendations on how I should proceed? Hardware RAID, 
ZFS or GEOM?

Some info that may help guide recommendations:

- 4GB of memory
- dual core 2.2Ghz
- I have no problem having /boot on a USB key
- preferably /backup to be ~1.6TB
- like to have a small piece of the disk encrypted (directory or partition)
- would be nice to be able to easily (ie: dynamically) add storage 
capacity without wiping existing data
- three GigE NICs, so would like to pursue the possibility of perhaps 
using disk space of other nodes (or at least mounting it remotely)
- would consider a RAID 5 setup if a recommendation meets other 
(non-listed) design objectives

Thanks all!

Steve