get two or three dedicated servers, stick a 2 disk mirrored raid in each one, run one primary and have barman manage your snapshots+streaming replication. hook

get two or three dedicated servers, stick a 2 disk mirrored raid in each one, run one primary and have barman manage your snapshots+streaming replication. hook in some cronjobs to monitor age of stuff and failure of stuff. that is pretty much it for anything less than, say, 5TB. Beyond that your copy times are too high and making snapshots becomes extremely difficult.