To enable automatic snapshots, place lines such as these into /etc/crontab:

    PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin
    15,30,45 * * * * root %%PREFIX%%/sbin/zfs-auto-snapshot frequent  4
    0        * * * * root %%PREFIX%%/sbin/zfs-auto-snapshot hourly   24
    7        0 * * * root %%PREFIX%%/sbin/zfs-auto-snapshot daily     7
    14       0 * * 7 root %%PREFIX%%/sbin/zfs-auto-snapshot weekly    4
    28       0 1 * * root %%PREFIX%%/sbin/zfs-auto-snapshot monthly  12

This will keep 4 15-minutely snapshots, 24 hourly snapshots, 7 daily snapshots,
4 weekly snapshots and 12 monthly snapshots. Any resulting zero-sized snapshots
will be automatically cleaned up.

Enable snapshotting on a dataset or top-level pool with:

    zfs set com.sun:auto-snapshot=true DATASET

Children datasets can be disabled for snapshot with:

    zfs set com.sun:auto-snapshot=false DATASET

Or for specific intervals:

    zfs set com.sun:auto-snapshot:frequent=false DATASET

See website and command usage output for further details.