Chapter 4 Troubleshooting
Common Problems and Solutions
Quantum DXi3500 and DXi5500 User’s Guide
140
NFS Performance
4
For optimal performance it is necessary to use 1000BaseT instead of
100BaseT. On NFS clients, use the
vers=3
,
rsize=262144
and
wsize=262144
mount options, and use TCP mounts instead of UDP.
When possible, it is also best to utilize TCP Offload capabilities as well as
jumbo frames.
It is best practice to have clients directly attached to the same network
switch as the NFS server. Any routing required for NFS traffic incurs
additional latency that impacts performance.
It is critical to make sure the
speed/duplex
settings are correct, because
this severely impacts performance. Most of the time
auto-detect
is the
correct setting. Some managed switches allow setting
speed/duplex
(for
example
1000Mb/full
,) which disables
auto-detect
and requires the host to
be set exactly the same. However, if the settings do not match between
switch and host, it severely impacts performance. For example, if the
switch is set to
auto-detec
t but the host is set to
1000Mb/full
, you will
observe a high error rate along with extremely poor performance. On
Linux, 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 network
performance characteristics.
