Minimal viable ZFS snapshot utility.
Add zfs-autosnap snap to your cron.hourly, and zfs-autosnap gc to
cron.daily; then set at.rollc.at:snapkeep=h24d30w8m6y1 (or whatever
is your retention policy) on datasets you want managed. Try
zfs-autosnap status to check what's going on.
Retenion policy is set via the property at.rollc.at:snapkeep, which
must be present on any datasets (filesystems or volumes) that you'd
like to be managed. The proposed default of h24d30w8m6y1 means to
keep 24 hourly, 30 daily, 8 weekly, 6 monthly and 1 yearly snapshots.
The garbage collector looks at every snapshot under the managed
datasets, and considers its creation time to decide whether to keep
it. The snapshot name does not matter! If you'd like to retain a
particular snapshot (e.g. right before a risky upgrade), set its
at.rollc.at:snapkeep property to a literal minus (-).
As always, when in doubt, consider reading the source: it's mere 400ish lines of relatively clean Rust.
It will try not to eat your data; the only destructive operation is contained within a function that will refuse to work on things that are not snapshots - but there's NO WARRANTY. Previous version (written in Python), was in production use since ca 2015 and there were zero incidents; this (Rust) version is basically a source port.
USE AT YOUR OWN RISK.