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I saw something EXACTLY like this way back in the 3.x days when I had a backend storage unit that had a flaky main memory issue and some enclosures were constantly flapping between controllers for ownership. Some NSDs were affected, some were not. I can imagine
this could still happen in 4.x and 5.0.x with the right hardware problem.</div>
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Were things working before or is this a new installation? <br>
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What is the backend storage?</div>
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If you are using device-mapper-multipath, look for events in the messages/syslog. Incorrect path weighting? Using ALUA when it isn't supported? (that can be comically bad! helped a friend diagnose that one at a customer once) Perhaps using the wrong rr_weight
or rr_min_io so you have some wacky long io queueing issues where your path_selector cannot keep up with the IO queue?
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Most of this is easily fixed by using most vendor's suggested settings anymore, IF the hardware is healthy...<br>
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Ed</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> gpfsug-discuss-bounces@spectrumscale.org <gpfsug-discuss-bounces@spectrumscale.org> on behalf of Saula, Oluwasijibomi <oluwasijibomi.saula@ndsu.edu><br>
<b>Sent:</b> Wednesday, June 3, 2020 5:45 PM<br>
<b>To:</b> gpfsug-discuss@spectrumscale.org <gpfsug-discuss@spectrumscale.org><br>
<b>Subject:</b> [gpfsug-discuss] Client Latency and High NSD Server Load Average</font>
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<div><span style="color:rgb(0,0,0); font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">Hello,</span></div>
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Anyone faced a situation where a majority of NSDs have a high load average and a minority don't?</div>
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Also, is 10x NSD server latency for write operations than for read operations expected in any circumstance? </div>
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We are seeing client latency between 6 and 9 seconds and are wondering if some GPFS configuration or NSD server condition may be triggering this poor performance.</div>
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<span style="font-family:Arial,sans-serif; font-size:13.3333px">Thanks,</span><br>
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<b><span style="margin:0px; font-size:10pt; font-family:Arial,sans-serif; color:black">Oluwasijibomi (Siji) Saula</span></b></p>
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