Loosely based on this guide.
scp unifiController-disk1.vmdk [email protected]:/pool1
convert -f vmdk /pool1/unifiController-disk1.vmdk -p -O raw /pool1/unifiController.raw
root@pedge:/pool1# ls -hapl /dev/zvol/pool1/ total 0 drwxr-xr-x 2 root root 660 Sep 16 11:33 ./ drwxr-xr-x 3 root root 60 Sep 11 21:39 ../ lrwxrwxrwx 1 root root 9 Sep 13 13:55 vm-100-disk-0 -> ../../zd0 lrwxrwxrwx 1 root root 10 Sep 13 13:55 vm-100-disk-1 -> ../../zd16 ... ... lrwxrwxrwx 1 root root 11 Sep 16 11:33 vm-107-disk-0 -> ../../zd144
dd if=/pool1/unifiController.raw of=/dev/zd144 bs=1M status=progress oflag=dsync