Having lost a drive recently I have decided to use take old HP SFF desktop and chuck in 4GB of RAM and run up an Open NAS box of some type.

I did the usual hunting around reading reviews looking at specs and came to the same conclusion, FreeNAS was the best but was too high spec’d hardware wise for me. For a start it basically requires a minimum of 8GB of RAM and I suspect more CPU power than I had. So I have gone with Open Media Vault as it is a compromise:

http://www.openmediavault.org/

Some OMV posts:

Installing Open Media Vault

Wipe a RAID disk

Open Media Vault FAQs

Access contents on a single disk from a Debian mirror array

Backing up Open Media Vault

Setting up a Windows shared drive

Setting up notifications for Open Media Vault