I’ve released my backup script under the GPL. Basically it uses rsync to copy the configured paths to a central backup system and snapshots the filesystem once all of the rsyncs are completed. The really nice thing about it is that it can run multiple rsyncs in parallel and has a very simple configuration. We use this to back up all 3 of our datacenters at the same time, which makes our backup jobs complete much faster.
You can find more information on the ZFS Backup Server page.
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