<span style=" font-size:10pt;font-family:sans-serif">Hi Kevin,</span><br><br><span style=" font-size:10pt;font-family:sans-serif">The I/O hist shown
by the command mmdiag --iohist actually depends on the node on which you
are running this command from.</span><br><span style=" font-size:10pt;font-family:sans-serif">If you are running
this on a NSD server node then it will show the time taken to complete/serve
the read or write I/O operation sent from the client node. </span><br><span style=" font-size:10pt;font-family:sans-serif">And if you are
running this on a client (or non NSD server) node then it will show the
complete time taken by the read or write I/O operation requested by the
client node to complete.</span><br><span style=" font-size:10pt;font-family:sans-serif">So in a nut shell
for the NSD server case it is just the latency of the I/O done on disk
by the server whereas for the NSD client case it also the latency of send
and receive of I/O request to the NSD server along with the latency of
I/O done on disk by the NSD server.</span><br><span style=" font-size:10pt;font-family:sans-serif">I hope this answers
your query.</span><br><br><br><span style=" font-size:10pt;font-family:sans-serif">Regards, The Spectrum
Scale (GPFS) team<br><br>------------------------------------------------------------------------------------------------------------------<br>If you feel that your question can benefit other users of Spectrum
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for priority messages to the Spectrum Scale (GPFS) team.</span><br><br><br><br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">From:
</span><span style=" font-size:9pt;font-family:sans-serif">"Buterbaugh,
Kevin L" <Kevin.Buterbaugh@Vanderbilt.Edu></span><br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">To:
</span><span style=" font-size:9pt;font-family:sans-serif">gpfsug
main discussion list <gpfsug-discuss@spectrumscale.org></span><br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Date:
</span><span style=" font-size:9pt;font-family:sans-serif">02/16/2019
08:18 PM</span><br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Subject:
</span><span style=" font-size:9pt;font-family:sans-serif">[gpfsug-discuss]
Clarification of mmdiag --iohist output</span><br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Sent
by: </span><span style=" font-size:9pt;font-family:sans-serif">gpfsug-discuss-bounces@spectrumscale.org</span><br><hr noshade><br><br><br><span style=" font-size:12pt">Hi All, </span><br><br><span style=" font-size:12pt">Been reading man pages, docs, and Googling,
and haven’t found a definitive answer to this question, so I knew exactly
where to turn… ;-)</span><br><br><span style=" font-size:12pt">I’m dealing with some slow I/O’s to
certain storage arrays in our environments … like really, really slow
I/O’s … here’s just one example from one of my NSD servers of a 10 second
I/O:</span><br><br><span style=" font-size:12pt">08:49:34.943186 W
data 30:41615622144 2048 10115.192 srv
dm-92 <client
IP redacted></span><br><br><span style=" font-size:12pt">So here’s my question … when mmdiag
—iohist tells me that that I/O took slightly over 10 seconds, is that:</span><br><br><span style=" font-size:12pt">1. The time from when the NSD server
received the I/O request from the client until it shipped the data back
onto the wire towards the client?</span><br><span style=" font-size:12pt">2. The time from when the client
issued the I/O request until it received the data back from the NSD server?</span><br><span style=" font-size:12pt">3. Something else?</span><br><br><span style=" font-size:12pt">I’m thinking it’s #1, but want to confirm.
Which one it is has very obvious implications for our troubleshooting
steps. Thanks in advance…</span><br><br><span style=" font-size:12pt">Kevin</span><br><span style=" font-size:12pt">—</span><br><span style=" font-size:12pt">Kevin Buterbaugh - Senior System Administrator</span><br><span style=" font-size:12pt">Vanderbilt University - Advanced Computing
Center for Research and Education</span><br><a href="mailto:Kevin.Buterbaugh@vanderbilt.edu"><span style=" font-size:12pt;color:blue"><u>Kevin.Buterbaugh@vanderbilt.edu</u></span></a><span style=" font-size:12pt">- (615)875-9633</span><br><tt><span style=" font-size:10pt">_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br></span></tt><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss"><tt><span style=" font-size:10pt">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</span></tt></a><tt><span style=" font-size:10pt"><br></span></tt><br><br><BR>