NFS Server Performance and Tuning Guide for Sun Hardware

Server Bottlenecks

This section (see Table 5-3) shows server bottlenecks and how to remedy them.

Table 5-3 Server Bottlenecks





NFS server hostname not responding

vmstat -s

or iostat

Cache hit rate is < 90% 

Adjust the suggested parameters for DNLC, then run to see if the symptom is gone. If not, reset the parameters for DNLC. Adjust the parameters for the buffer cache, then the inode cache, following the same procedure as for the DNLC. 

NFS server hostname not responding

netstat -m

or nfsstat

Server not keeping up with request arrival rate 

Check the network. If the problem is not the network, add appropriate Prestoserve NFS accelerator, or upgrade the server. 

High I/O wait time or CPU idle time; slow disk access times or NFS server hostname not responding

iostat -x

I/O load not balanced across disks; the svc_t value is greater than 40 ms

Take a large sample (~2 weeks). Balance the load across disks; add disks as necessary. Add a Prestoserve NFS accelerator for synchronous writes. To reduce disk and network traffic, use tmpfs for /tmp for both server and clients. Measure system cache efficiencies. Balance load across disks; add disks as necessary.

Slow response when accessing remote files 

netstat -s

or snoop

Ethernet interface dropping packets 

If retransmissions are indicated, increase buffer size. For information on how to use snoop, see "snoop"" in Appendix A, Using NFS Performance-Monitoring and Benchmarking Tools.