david@tasman.cc.utas.edu.au (David Nyman) (11/20/90)
I am having problems with NFS performance on our network. Our network consists of: 1. Two Sun 4/330's, 2. One VAX 6310 with 13 DEC terminal servers, and 3. One Vista terminal server, supporting 16 terminals for either LAT or TCP/IP connections. If I NFS mount a filesystem from the Sun NFS server on the Sun NFS client, access to the NFS filesystem on the client is abysmally slow (up to about 20 seconds for a 'pwd', for instance). 'nfsstat' will also report retransmissions and timeouts at the rate of about 30% !! This performance is not always reproducible - some NFS filesystem accesses are normal, but most suffer with the above symptoms (this is perhaps due to caching). I have attempted isolating the Sun/4's from the network, and, hey presto, the problem goes away !! No 'nfsstat' errors, timely responses, and all is rosy. Reconnecting to the network brings the problem back. Has anyone had similar problems? I firstly wondered if the VAX was swamping the network, even though it is only servicing the terminal servers. I find this hard to believe, but I'm open to any suggestions. It's also important to note that other network services (telnet, rlogin, rcp, etc) do not suffer from any degradation in performance. This is only a subjective comment, but if there is a problem with the other services it is nowhere as apparent as with NFS. Also, the nfs daemons on the NFS server do not accumulate CPU time ???? Hope someone can help, Dave.