First thing you need to decide is buy off the shelf NAS or make your own based on some hardware you may have lying around. I have an old TS140 with an i3 that

First thing you need to decide is buy off the shelf NAS or make your own based on some hardware you may have lying around. I have an old TS140 with an i3 that can take 4 HD, has ECC RAM with 4 slots. I'm currently exploring setting it up with Freenas (or Truenas after the merge) based on ZFS. So far it looks pretty good and performant. For off the shelf NAS, Synology options look good..