The ideal case would be to get a new ZFS system and copy over the network. Depending on how big your data is, and how many spare drives you have, you could prob

The ideal case would be to get a new ZFS system and copy over the network. Depending on how big your data is, and how many spare drives you have, you could probably do something hacky like creating a small ZFS pool on linux, empty a btrfs drive, and then move it over to ZFS. At that point you could export that system and switch over to FreeNAS. But the end result wouldn't be optimal, pretty far from it. edit: just to clarify ZFS under Linux isn't hacky, ubuntu 16.04 makes it pretty nice, rather this particular suggestion is hacky.