Managing NFS and NIS, 2nd Edition

Chapter 18. Client-Side Performance Tuning

The performance measurement and tuning techniques we’ve discussed so far have only dealt with making the NFS server go faster. Part of tuning an NFS network is ensuring that clients are well-behaved so that they do not flood the servers with requests and upset any tuning you may have performed. Server performance is usually limited by disk or network bandwidth, but there is no throttle on the rate at which clients generate requests unless you put one in place. Add-on products, such as the Solaris Bandwidth Manager, allow you to specify the amount of network bandwidth on specified ports, enabling you to restrict the amount of network resources used by NFS on either the server or the client. In addition, if you cannot make your servers or network any faster, you have to tune the clients to handle the network “as is.”

Slow server compensation

The RPC retransmission algorithm cannot distinguish between a slow server and a congested network. If a reply is not received from the server within the RPC timeout period, the request is retransmitted subject to the timeout and retransmission parameters for that mount point. It is immaterial to the RPC mechanism whether the original request is still enqueued on the server or if it was lost on the network. Excessive RPC retransmissions place an additional strain on the server, further degrading response time.

Identifying NFS retransmissions

Inspection of the load average and disk activity on the servers ...