2007-12-15 19:54:32

by Mark Seger

[permalink] [raw]
Subject: Am I the only one who finds nfsstat pretty useless?

When I want to monitor what's happening with nfs, I want a
second-by-second view of what's happening and while that usually
involved many of the counters in nfsstat, they're not particularly
useful in their present form. When I wrote collectl (see
http://collectl.sourceforge.net/), which shows just about any
performance counter you can think of all nicely formatted, I couldn't
help but add nfs counters as well. Now you can see them all on a single
line (I'm currently talking V2 and V3 but am planning on adding V4 some
time soon). I have used the output to show fluctuations in the commit
rates from a few a second to over 1K per second! This was particularly
helpful in finding problems trying to write over 1M files to the same
directory in an xfs file system.

I don't know how well these examples will show up if they're reformatted
by mail, but here are just a few different formats for displaying nfs
data, in some cases mixed with other types as controlled by -s which
lets you specify the type of data you want to see including cpu, disk,
network, lustre, infiniband, nfs, sockets, inodes, slabs, processes and
perhaps one or two more I forgot to list:

[[email protected] collectl]# collectl -oT -scmf
# <--------CPU--------><-----------Memory----------><--NFS Svr
Summary-->
#Time cpu sys inter ctxsw free buff cach inac slab map read
write calls
14:49:58 0 0 136 31 13M 495M 2G 562M 0 0 0
0 0
14:49:59 1 1 144 45 13M 495M 2G 562M 0 0 0
0 0
14:50:00 0 0 156 63 13M 495M 2G 562M 0 0 0
0 0

[[email protected] collectl]# collectl -oT -scFnd
#
<--------CPU--------><-----------Disks-----------><-----------Network----------><----NFS
MetaOps---->
#Time cpu sys inter ctxsw KBRead Reads KBWrit Writes netKBi
pkt-in netKBo pkt-out meta commit retran
14:50:38 0 0 133 27 0 0 236 7 0
6 0 2 0 0 0
14:50:39 8 8 147 36 0 0 0 0 0
2 0 0 0 0 0

[[email protected] collectl]# collectl -oT -sf --verbose
# NFS SERVER (/sec)
# <----------Network-------><----------RPC---------><---NFS V3--->
# PKTS UDP TCP TCPCONN CALLS BADAUTH BADCLNT READ WRITE
14:51:37 0 0 0 0 0 0 0 0 0
14:51:38 0 0 0 0 0 0 0 0 0
14:51:39 0 0 0 0 0 0 0 0 0

[[email protected] collectl]# collectl -oT -sF --verbose
# NFS V3 SERVER (/sec)
# NULL GETA SETA LOOK ACCS RLNK READ WRIT CRE8 MKDR SYML MKND
RMOV RMDR RENM LINK RDIR RDR+ FSTA FINF PATH COMM
14:52:18 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
14:52:19 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
14:52:20 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0

naturally this would look a lot more meaningful with real nfs traffic
and all this data can be reported interactively or written to rolling
log files for later playback and can also be recorded in space-separated
format making it easy to display with gnuplot. But don't just take my
word for it, download a copy and try it out yourselves.

-mark