"The normal timeout logic can take care of retransmission in the unlikely case that one is needed."

NFS can be run over TCP or UDP. Does the retransmission occur when using UDP?

Yes! The retransmission logic in Linux NFS is independent of transport (see the `retrans` option in `mount.nfs`).

Weirdly enough this also means that if you’re running with TCP you can have retransmits at the NFS/SunRPC level and at the TCP level depending on your configuration.