Re: Cost
"It is all too easy to get carried away reading a paper on e.g. ZFS and thinking that it answers all your problems at a stroke."
ZFS answers several problems, which is why I'm in the process of installing a 400TB system at the moment, but it's not a backup or archive solution and never claims to be. Snapshots are for when someone fatfingers a couple of file deletions and that's about it.