Periodic export of ZFS pool to external USB drive
[root@freenas] ~# zpool list
NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
archive 7.25T 4.17T 3.08T - 14% 57% 1.00x ONLINE /mnt
freenas-boot 3.72G 2.27G 1.45G - - 60% 1.00x ONLINE -
usb-backups 1.81T 396K 1.81T - 0% 0% 1.00x ONLINE /mnt
# Intial
zfs snapshot -r archive/backups@2015-09-22
zfs send -R archive/backups@2015-09-22 | zfs receive -vF usb-backups
...
# Incremental afer that
zfs snapshot -r archive/backups@2015-09-23
zfs send -I archive/backups@2015-09-22 archive/backups@2015-09-23 | zfs receive -vF usb-backups
# export the backup pool
zpool export usb-backups
# decrypt device ...
# import the backup pool
zpool import usb-backups