You can already do offline/lazy dedupe. zfs set mountpoint=foopy/foo /mnt/foo zfs set dedup=off foopy/foo zfs set mountpoint=foopy/baz /mnt/baz zfs s

You can already do offline/lazy dedupe. zfs set mountpoint=foopy/foo /mnt/foo zfs set dedup=off foopy/foo zfs set mountpoint=foopy/baz /mnt/baz zfs set dedup=on foopy/baz Save all your stuff in /mnt/foo, then when you want to dedup do mv /mnt/foo/bar /mnt/baz/ Yeah... this feels like picrel, and it is https://i.pinimg.com/originals/cb/09/16/cb091697350736aae53afe4b548b9d43.jpg but it's here and now and you can do it now.