This message appears on an NFS client that requested a service from an NFS server whose hardware is failing. Often the message "NFS read failed" appears along with this message. If the server were merely down or slow to respond, the "NFS server not responding" message would appear instead. Data corruption on the server system is possible.
Because this message usually indicates server hardware failure, initiate repair procedures as soon as possible. Check the memory modules, disk controllers, and CPU board.
For more information on NFS tuning, see chapter on monitoring network performance in the System Administration Guide, Volume II.