Rsync needed
On your project notes it states that you don't need rsync for the render nodes - well that certainly wasn't the case for me. I'm running a raspi3 cluster on raspian-lite. Rsync isn't installed as standard on that. It was failing on virtually all the nodes saying it could't retrieve the data. It was only when I twigged that the one node it wasn't failing on was one where I had installed rsync that I realised the problem. So... you might want to change your project page slightly to acknowledge that (at least on Raspian)
Cheers,
Chris. chris@chrislongbone.co.uk