Hello again 
I’m about to setup rsync to backup the most critical files from my freenas nas to an spare laptop running Ubuntu.
Ubuntu is logged into the freenas share with it’s file manager. It’s the laptop that has the job of running rsync.
The freenas nas is only doing storage. That way I don’t accidentally fuck up freenas and all my files setting up jails etc…
Now, is rsync one way by default? I want it to backup from freenas to Ubuntu, one way only.
So if freenas finds and corrects bitrot/corruption during a scrub, rsync doesn’t look a the Ubuntu file version and syncs that to freenas, effectively working against the ZFS magic?
So is rsync one way “out of the box” or do I have to configure it to be that?
Well I sure hope it’s one-way by default because I’ve been relying on that behaviour for non-system backups for over decade!
Set up your rsync script to backup a test directory over to another test directory to begin with. That’ll at the very least sort out whether you need a trailing slash or not (I always seem to get that wrong).