I'm guessing this would require changes to the upstream docker images and probably isn't going to happen.  I realise there's not many using ZFS in unraid, but in case anyone else comes across this problem, I've "fixed" it with a disgusting user scripts hack.   I have this running in User Scripts every 5 minutes, it will: Check if lancache-bundle docker is running If so, it will check the "sendfile" setting in nginx.conf inside the docker If nginx.conf is set to "s