Create zfs-geek-backup.sh

This script will backup select datasets to zfs pool.
The pool can be on a USB harddrive, I use a USB drive dock
and several old SATA drives.
You may have switch drives whenever you like, only changes from get
transfered and snapshots on the USB drive mean you can have many
versions of your data going back (in my case) months and months.
 
If you have prepared the USB drive then simply
physically attach the drive to a server USB port
Run this script or let cron do it.

To prepared a drive:
zpool create MyBackup da1
(where da1 is assigned by your system
 and might be something else on your machine)

Written and tested on NAS4Free 9.1.0.1 - Sandstorm (revision 636)