To get full rsync backups from a server on your FreeNAS box you have a couple of options. It took me some time to get used to the read-only FS regarding the / partition. When you want to login on another server with your root account you’ll get a SSH alert that you have to confirm with “yes”. Obviously this will not be saved on the read-only FS. So to get this working you have to remount / with write partitions, do your change and remount readonly again.