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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi Lohit,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">What type of network are you using on the back end to transfer the GPFS traffic?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Best,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Dwayne<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gpfsug-discuss-bounces@spectrumscale.org [mailto:gpfsug-discuss-bounces@spectrumscale.org]
<b>On Behalf Of </b>valleru@cbio.mskcc.org<br>
<b>Sent:</b> Tuesday, May 22, 2018 1:13 PM<br>
<b>To:</b> gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Subject:</b> [gpfsug-discuss] Critical Hang issues with GPFS 5.0. Downgrading from GPFS 5.0.0-2 to GPFS 4.2.3.2<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Hello All,
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">We have recently upgraded from GPFS 4.2.3.2 to GPFS 5.0.0-2 about a month ago. We have not yet converted the 4.2.2.2 filesystem version to 5. ( That is we have not run the mmchconfig
release=LATEST command)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Right after the upgrade, we are seeing many “ps hangs" across the cluster. All the “ps hangs” happen when jobs run related to a Java process or many Java threads (example: GATK
)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">The hangs are pretty random, and have no particular pattern except that we know that it is related to just Java or some jobs reading from directories with about 600000 files.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">I have raised an IBM critical service request about a month ago related to this - PMR: 24090,L6Q,000. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">However, According to the ticket - they seemed to feel that it might not be related to GPFS. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Although, we are sure that these hangs started to appear only after we upgraded GPFS to GPFS 5.0.0.2 from 4.2.3.2.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">One of the other reasons we are not able to prove that it is GPFS is because, we are unable to capture any logs/traces from GPFS once the hang happens.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Even GPFS trace commands hang, once “ps hangs” and thus it is getting difficult to get any dumps from GPFS.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Also - According to the IBM ticket, they seemed to have a seen a “ps hang" issue and we have to run mmchconfig release=LATEST command, and that will resolve the issue.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">However we are not comfortable making the permanent change to Filesystem version 5. and since we don’t see any near solution to these hangs - we are thinking of downgrading to
GPFS 4.2.3.2 or the previous state that we know the cluster was stable.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Can downgrading GPFS take us back to exactly the previous GPFS config state? <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">With respect to downgrading from 5 to 4.2.3.2 -> is it just that i reinstall all rpms to a previous version? or is there anything else that i need to make sure with respect to
GPFS configuration?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Because i think that GPFS 5.0 might have updated internal default GPFS configuration parameters , and i am not sure if downgrading GPFS will change them back to what they were
in GPFS 4.2.3.2<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Our previous state:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">2 Storage clusters - 4.2.3.2<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">1 Compute cluster - 4.2.3.2 ( remote mounts the above 2 storage clusters )<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Our current state:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">2 Storage clusters - 5.0.0.2 ( filesystem version - 4.2.2.2)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">1 Compute cluster - 5.0.0.2<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Do i need to downgrade all the clusters to go to the previous state ? or is it ok if we just downgrade the compute cluster to previous version?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Any advice on the best steps forward, would greatly help.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Thanks,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif">Lohit<o:p></o:p></span></p>
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