zfsnap makes rolling ZFS snapshots easy and - with cron - automatic.

The main advantages of zfsnap are its portability, simplicity, and performance.
It is written purely in /bin/sh and does not require any additional software -
other than a few core *nix utilies.

zfsnap stores all the information it needs about a snapshot directly in its
name; no database or special ZFS properties are needed. The information is
stored in a way that is human readable, making it much easier for a sysadmin to
manage and audit backup schedules.

Snapshot names are in the format of pool/fs@[prefix]Timestamp--TimeToLive
(e.g. pool/fs@weekly-2014-04-07_05.30.00--6m). The prefix is optional but can
be quite useful for filtering, Timestamp is the date and time when the snapshot
was created, and TimeToLive (TTL) is the amount of time the snapshot will be
kept until it can be deleted.