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<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">The performance impact can be quite significant depending on what you are tracing. We even having monitoring that looks for long running traces and the recommended action is to “kill with impunity!!”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">I believe IBM recommends never running clusters with continuous tracing.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">-Bryan<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt">From:</span></b><span style="font-size:11.0pt"> gpfsug-discuss-bounces@spectrumscale.org [mailto:gpfsug-discuss-bounces@spectrumscale.org]
<b>On Behalf Of </b>Oesterlin, Robert<br>
<b>Sent:</b> Tuesday, March 07, 2017 2:33 PM<br>
<b>To:</b> gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Subject:</b> [gpfsug-discuss] Potential problems - leaving trace enabled in over-write mode?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I’m considering enabling trace on all nodes all the time, doing something like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">mmtracectl --set --trace=def --trace-recycle=global --tracedev-write-mode=overwrite --tracedev-overwrite-buffer-size=256M<br>
mmtracectl --start<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">My questions are:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">- What is the performance penalty of leaving this on 100% of the time on a node?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">- Does anyone have any suggestions on automation on stopping trace when a particular event occurs?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">- What other issues, if any?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal">Bob Oesterlin<br>
Sr Principal Storage Engineer, Nuance<br>
507-269-0413<o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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