NFS dynamics over flow-controlled wide area networks

The network file system protocol (NFS) has been the leading distributed file system for workstations since it was first introduced by Sun Microsystems in 1986. The geographical scale of NFS has been limited to the local area due to its relatively low performance on the wide area Internet. However, with the advent of high bandwidth wide area networks such as ATM, NFS over WANs may become more promising. In this paper, the performance of NFS over various sizes of WAN is studied The effects of ATM flow-control and queueing strategies on NFS are discussed, as are the performance of TCP and UDP as NFS transport protocols. The primary conclusion is that standard NFS over UDP works well over ATM WANs as long as ATM-level flow control keeps the cell loss rate under one percent. In some cases, NFS over TCP works badly with small packets due to unfortunate interactions with TCP's congestion window.