nfsstat

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nfsstat

nfsstat can be used to examine NFS performance.

nfsstat -s reports server-side statistics. In particular, the following are important:

calls: Total RPC calls received.
badcalls: Total number of calls rejected by the RPC layer.
nullrecv: Number of times an RPC call was not available even though it was believed to have been received.
badlen: Number of RPC calls with a length shorter than that allowed for RPC calls.
xdrcall: Number of RPC calls whose header could not be decoded by XDR (External Data Representation).
readlink: Number of times a symbolic link was read.
getattr: Number of attribute requests.
null: Null calls are made by the automounter when looking for a server for a filesystem.
writes: Data written to an exported filesystem.

Sun recommends the following tuning actions for some common conditions:

writes > 10%: Write caching (either array-based or host-based, such as a Prestoserv card) would speed up operation.
badcalls >> 0: The network may be overloaded and should be checked out. The rsize and wsize mount options can be set on the client side to reduce the effect of a noisy network, but this should only be considered a temporary workaround.
readlink > 10%: Replace symbolic links with directories on the server.
getattr > 40%: The client attribute cache can be increased by setting the actimeo mount option. Note that this is not appropriate where the attributes change frequently, such as on a mail spool. In these cases, mount the filesystems with the noac option.

nfsstat -c reports client-side statistics. The following statistics are of particular interest:

calls: Total number of calls made.
badcalls: Total number of calls rejected by RPC.
retrans: Total number of retransmissions. If this number is larger than 5%, the requests are not reaching the server consistently. This may indicate a network or routing problem.
badxid: Number of times a duplicate acknowledgement was received for a single request. If this number is roughly the same as badcalls, the network is congested. The rsize and wsize mount options can be set on the client side to reduce the effect of a noisy network, but this should only be considered a temporary workaround.
If on the other hand, badxid=0, this can be an indication of a slow network connection.
timeout: Number of calls that timed out. If this is roughly equal to badxid, the requests are reaching the server, but the server is slow.
wait: Number of times a call had to wait because a client handle was not available.
newcred: Number of times the authentication was refreshed.
null: A large number of null calls indicates that the automounter is retrying the mount frequently. The timeo parameter should be changed in the automounter configuration.

nfsstat -m (from the client) provides server-based performance data.

srtt: Smoothed round-trip time. If this number is larger than 50ms, the mount point is slow.
dev: Estimated deviation.
cur: Current backed-off timeout value.
Lookups: If cur>80 ms, the requests are taking too long.
Reads: If cur>150 ms, the requests are taking too long.
Writes: If cur>250 ms, the requests are taking too long.

Old News ;-)

pSeries and AIX Information Center

The nfsstat command displays statistical information about the NFS and the RPC interface to the kernel for clients and servers.
This command could also be used to re-initialize the counters for these statistics (nfsstat -z). For performance issues, the RPC statistics (-r option) are the first place to look. The NFS statistics show you how the applications use NFS.

RPC statistics
The nfsstat command displays statistical information about RPC calls.

Parent topic: NFS statistics and tuning parameters

Linux Command Directory nfsstat

nfsstat [options]

System administration command. Print statistics on NFS and remote procedure call (RPC) activity for both clients and server.

Options
-a

Display all statistics.

-c

Display only client-side statistics.

-n

Display only NFS statistics.

-r

Display only RPC statistics.

-s

Display only server-side statistics.

-o facility

Only display statistics for the specified facility. The following are valid values for facility:
fh

Server file handle cache.

net

Network layer statistics.

nfs

Same as -n.

rc

Server request reply cache.

rpc

Same as -r.

-z

Reset statistics to zero. Use with above options to zero out specific sets of statistics (e.g. -zr to reset the RPC statistics.)

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Last modified: February 28, 2008