Backup

1. Take a snapshot

Take a snapshot of the zpool you wish to backup

zfs snapshot tank@backup-jan-2020

2. Find external drive

Find the drive path for the external drive

For example, with a 64GB USB drive:

fdisk -l | grep 'Disk /dev'
[...]
Disk /dev/sdn: 62.4 GB, 62411243520 bytes, 121896960 sectors

/dev/sdn is the path we're interested in and will use in this tutorial.

3. Create zpool on external drive

Create a zpool on the destination drive. No need to format the drive.

zpool create backup1 /dev/sdn

4. Send snapshot to external drive

Send the snapshot to the external drive, this may take some time.

zfs send tank@backup-jan-2020 | pv | zfs recv -F backup1

5. Verify snapshot size

Compare the size of the snapshot on your data volume to the snapshot on the external volume.

The REFER amount should match.

zfs list -t snapshot | grep 'backup-jan-2020'
NAME                      USED  AVAIL  REFER  MOUNTPOINT
tank@backup-jan-2020      392K      -  1.79T  -
backup1@backup-jan-2020   0B        -  1.79T  -

6. Export the external zpool

Export the external zpool so your machine isn't looking for it

zpool export backup1

7. Power off the USB Drive (Optional)

udisksctl power-off -b /dev/sdn

Restore

1. Import the external zpool

Import the external zpool by name, or use zfs import to find the name

zfs import backup1

This should automatically mount it at /backup1, if not use zfs mount backup1 to force a mount.

2. Verify backup snapshot

Ensure a backup snapshot is present on the external drive

zfs list -t snapshot | grep backup1
NAME                      USED  AVAIL  REFER  MOUNTPOINT
backup1@backup-jan-2020   0B        -  1.79T  -

3. Send the snapshot from the external drive to the data volume

Send the snapshot to the data volume, this may take some time.

zfs send backup1@backup-jan-2020 | pv | zfs recv tank

4. Verify snapshot size