Chapter 4 TroubleshootingCommon Problems and SolutionsQuantum DXi3500 and DXi5500 User’s Guide 140NFS Performance 4 For optimal performance it is necessary to use 1000BaseT instead of100BaseT. On NFS clients, use the vers=3, rsize=262144 andwsize=262144 mount options, and use TCP mounts instead of UDP.When possible, it is also best to utilize TCP Offload capabilities as well asjumbo frames.It is best practice to have clients directly attached to the same networkswitch as the NFS server. Any routing required for NFS traffic incursadditional latency that impacts performance.It is critical to make sure the speed/duplex settings are correct, becausethis severely impacts performance. Most of the time auto-detect is thecorrect setting. Some managed switches allow setting speed/duplex (forexample 1000Mb/full,) which disables auto-detect and requires the host tobe set exactly the same. However, if the settings do not match betweenswitch and host, it severely impacts performance. For example, if theswitch is set to auto-detect but the host is set to 1000Mb/full, you willobserve a high error rate along with extremely poor performance. OnLinux, the ethtool tool can be very useful to investigate and adjust speed/duplex settings.It can be useful to use a tool such as netperf to help verify networkperformance characteristics.
