AIX 5L Problem Determination - IBM Redbooks

If the total number of collisions from the netstat -v output (for Ethernet) is
greater than 10 percent of the total transmitted packets, using the following
formula, the system may have a high network load:
Number of collisions / Number of Transmit Packets > 0.1
If the system suffers from extensive NFS load, the nfsstat command provides
useful information.
10.4.2 The nfsstat command
NFS gathers statistics on types of NFS operations performed, along with error
information and performance indicators. You can use the nfsstat command to
identify network problems and observe the type of NFS operations taking place
on your system. The nfsstat command displays statistical information about the
NFS and Remote Procedure Call (RPC) interfaces to the kernel. You can also
use this command to reinitialize this information. The nfsstat command splits its
information into server and client parts. The following commands can be used to
match a particular need:
► nfsstat -r (to see the application NFS statistics)
The output is divided into server connection oriented and connectionless, as
well as client connection oriented and connectionless.
► nfsstat -s (to see the server statistics)
The NFS server displays the number of NFS calls received (calls) and
rejected (badcalls) due to authentication, as well as the counts and
percentages for the various kinds of calls made.
► nfsstat -c (to see the client statistics)
The NFS client displays the number of calls sent and rejected, as well as the
number of times a client handle was received (clgets) and a count of the
various kinds of calls and their respective percentages. For performance
monitoring, the nfsstat -c command provides information on whether the
network is dropping UDP packets. A network may drop a packet if it cannot
handle it. Dropped packets can be the result of the response time of the
network hardware or software, or an overloaded CPU on the server. Dropped
packets are not actually lost, because a replacement request is issued for
them.
A high badxid count implies that requests are reaching the various NFS
servers, but the servers are too loaded to send replies before the client's RPC
calls time out and are retransmitted. The badxid value is incremented each
time a duplicate reply is received for a transmitted request (an RPC request
retains its XID through all transmission cycles). Excessive retransmissions
place an additional strain on the server, further degrading response time.
Chapter 10. Performance problem determination 273