NFS Server Performance and Tuning Guide for Sun Hardware

General Troubleshooting Tuning Tips

This section (see Table 5-1) lists the actions to perform when you encounter a tuning problem.

Table 5-1 General Troubleshooting Tuning Problems and Actions to Perform


Command Output/Result 


netstat -i

Collis+Ierrs+Oerrs/Ipkts + Opkts > 2%

Check the Ethernet hardware. 

netstat -i

Collis/Opkts > 10%

Add an Ethernet interface and distribute the client load. 

netstat -i

Ierrs/Ipks > 25%

The host may be dropping packets, causing high input error rate. To compensate for bandwidth-limited network hardware: reduce the packet size; set the read buffer size, rsize and/or the write buffer size wsize to 2048 when using mount or in the /etc/vfstab file. See "To Check the Network" in Chapter 3, Analyzing NFS Performance.

nfsstat -s

readlink > 10%

Replace symbolic links with mount points. 

nfsstat -s

writes > 5%

Install a Prestoserve NFS accelerator (SBus card or NVRAM-NVSIMM) for peak performance. See "Prestoserve NFS Accelerator" in Chapter 4, Configuring the Server and the Client to Maximize NFS Performance.

nfsstat -s

There are any badcalls.

The network may be overloaded. Identify an overloaded network using network interface statistics. 

nfsstat -s

getattr > 40%

Increase the client attribute cache using the actimeo option. Make sure the DNLC and inode caches are large. Use vmstat -s to determine the percent hit rate (cache hits) for the DNLC and, if needed, increase ncsize in the /etc/system file. See "Directory Name Lookup Cache (DNLC)"in Chapter 4, Configuring the Server and the Client to Maximize NFS Performance.

vmstat -s

Hit rate (cache hits) < 90% 

Increase ncsize in the /etc/system file.

Ethernet monitor, for example: 

SunNet Manager SharpShooter, NetMetrix  

Load > 35% 

Add an Ethernet interface and distribute client load.