Recovery

A ZFS snapshot is a name attached to a dataset’s block tree at one transaction group. Nothing is copied, nothing is quiesced, and the cost is a few metadata blocks: zfs snapshot tank/data@before-upgrade returns before the shell prompt redraws. Because ZFS never overwrites a live block in place, the old tree stays valid on disk until the last reference to it goes away, and the snapshot is that reference. ...

A completed backup job establishes that the backup process produced an artifact. A restore rehearsal establishes whether that artifact, the available tooling, and the required environment can produce a usable system. These are different claims. Recovery evidence should identify the backup used, the state recovered, the dependencies supplied, and the time needed to make the result useful to the application. ...

Choose a small recovery unit, verify it, and practice restoring it somewhere disposable.