The version of NFS that has been most commonly used is NFS Version 2. Technology has rolled on ahead and it has begun to show weaknesses that only a revision of the protocol could overcome. Version 3 of the Network File System supports larger files and filesystems, adds significantly enhanced security, and offers a number of performance improvements that most users will find useful.
Olaf Kirch and Trond Myklebust are developing an experimental NFSv3 server. It is featured in the developer Version 2.3 kernels and a patch is available against the 2.2 kernel source. It builds on the Version 2 kernel-based NFS daemon.
The patches are available from the Linux Kernel based NFS server home page at http://csua.berkeley.edu/~gam3/knfsd/.