NFS Version 3 Protocol

An implementation of NFS version 3 protocol was a new feature of the Solaris 2.5 release. Several changes have been made to improve interoperability and performance. For optimal use, the version 3 protocol must be running on both the NFS servers and clients.

This version enables safe asynchronous writes on the server, which improve performance by allowing the server to cache client write requests in memory. The client does not need to wait for the server to commit the changes to disk, so the response time is faster. Also, the server can batch the requests, which improves the response time on the server.

All Solaris NFS version 3 operations return the file attributes, which are stored in the local cache. Because the cache is updated more often, the need to do a separate operation to update this data arises less often. Therefore, the number of RPC calls to the server is reduced, improving performance.

The process for verifying file access permissions has been improved. Specifically, version 2 generated a message that reported a "write error" or a "read error" if users tried to copy a remote file to which they did not have permissions. In version 3, the permissions are checked before the file is opened, so the error is reported as an "open error."

The NFS version 3 protocol removes the 8-Kbyte transfer size limit. Clients and servers negotiate whatever transfer size they support, rather than conform to the 8-Kbyte limit imposed in version 2. The Solaris 2.5 implementation defaults to a 32-Kbyte transfer size.