Red Hat Knowledgebase

NFS version 3 and above allow for either TCP and UDP to be the transport protocol for NFS data.

The choice of protocol to use depends on the network conditions. The advantages of using either for using a specific protocol are outlined below.

Advantages of UDP: UDP traditionally uses less CPU and network overhead than TCP.

Advantages of TCP: NFS over TCP handles multi speed networks more efficiently (networks where the links connecting the server and the client use different speeds).

When using NFS over high latency links or links with higher levels of packet loss and congestion, the TCP protocol allows routers to be able to retransmit the lost or out of order packets, rather than the originating host.

Conclusion

The TCP protocol is considered a sensible choice for both performance and reliability across most network situations. A possible downside is that TCP may be more processor (CPU) intensive. Unless CPU usage becomes an issue, consider configuring the clients to mount the NFS server using TCP.