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Yes, but if you are storing the output of zfs send for each snapshot (incrementally) you won't get the benefit of it using a merkle tree on the storage side of things (obviously it's used among other neat algorithms to figure out what the delta between snapshots is).

If you are using zfs recv on the remote server you will get basically the same features as restic (minus content-defined deduplication, and full-repo encryption -- ZFS has extent-based dedup and its built-in encryption is not "full-disk" since it reveals ZFS-level metadata). And you get real atomic snapshots which is better than what restic can give you because it's a userspace tool (though you can always use restic with ZFS).

I'm not sure we're actually in disagreement on how ZFS works, it's a question of whether you can get the practicalities of the benefits without having a ZFS server which holds your backups. If you just store the out of zfs send then it's also hard to expire old backups, and restoring would require applying all of the saved send payloads rather than just doing one 'zfs send' from the remote server.




Sure, zfs send does not actually send a section of a blockchain. It could have, but that wouldn't have been as space-efficient.


In order for ZFS send to be able to provide the same features as restic it would need to output a representation of the zfs merkle tree as a flat filesystem (but encrypted) -- which would allow a dumb server to deduplicate the tree (and ZFS is clever enough to already know what blobs exist on the remote side). I guess this was not done because a ZFS send stream might be more efficient for transfer (as you said). But this means that it's main use as a backup system requires having a ZFS server on the other end (in order to be efficient and useful as a backup store).

Again, I'm not bashing ZFS. My whole point is that restic is a neat and interesting project specifically because it doesn't require a clever server to provide its features -- that doesn't mean ZFS isn't a great project (far from it).

I use ZFS on my servers and love it, and I use restic for backups.




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