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<p class="MsoNormal">I’ve used ‘preferDesignatedMnode=1’ in the past, but that was for a specific usecase, and that would have to come from the direction of support.<o:p></o:p></p>
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<p class="MsoNormal">I guess if you wanted to test your metanode theory, you could open that file (and keep it open) on node from a different remote cluster, or one of your local NSD servers and see what kind of results you get out of it.<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"-webkit-standard",serif;color:black">----<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"-webkit-standard",serif;color:black">Steve Crusan<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"-webkit-standard",serif;color:black"><a href="mailto:scrusan@ddn.com">scrusan@ddn.com</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"-webkit-standard",serif;color:black">(719) 695-3190<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black"><gpfsug-discuss-bounces@spectrumscale.org> on behalf of Marc A Kaplan <makaplan@us.ibm.com><br>
<b>Reply-To: </b>gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Date: </b>Tuesday, July 10, 2018 at 11:16 AM<br>
<b>To: </b>gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Subject: </b>Re: [gpfsug-discuss] Same file opened by many nodes / processes<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">I would start by making sure that the application(s)... open the file O_RDONLY and then you may want to fiddle with the GPFS atime settings:</span><br>
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<a href="https://www.ibm.com/support/knowledgecenter/en/STXKQY_4.2.0/com.ibm.spectrum.scale.v4r2.ins.doc/bl1ins_atime.htm"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">https://www.ibm.com/support/knowledgecenter/en/STXKQY_4.2.0/com.ibm.spectrum.scale.v4r2.ins.doc/bl1ins_atime.htm</span></a><span style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
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<span style="font-size:10.0pt;font-family:"Arial",sans-serif">At first I thought "uge" was a typo, but I guess you are referring to:
</span><br>
<a href="https://supcom.hgc.jp/english/utili_info/manual/uge.html"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">https://supcom.hgc.jp/english/utili_info/manual/uge.html</span></a><br>
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<span style="font-size:10.0pt;font-family:"Arial",sans-serif">Still not begin familiar, it would be "interesting" to know from a file operations point of view, what's going on in terms of opens, reads, closes : per second.</span><br>
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<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">From: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">Peter Childs <p.childs@qmul.ac.uk></span><br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">To: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">"gpfsug-discuss@spectrumscale.org" <gpfsug-discuss@spectrumscale.org></span><br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Date: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">07/10/2018 10:51 AM</span><br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Subject: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">[gpfsug-discuss] Same file opened by many nodes / processes</span><br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Sent by: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">gpfsug-discuss-bounces@spectrumscale.org</span><o:p></o:p></p>
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<tt><span style="font-size:10.0pt">We have an situation where the same file is being read by around 5000</span></tt><span style="font-size:10.0pt;font-family:"Courier New""><br>
<tt>"jobs" this is an array job in uge with a tc set, so the file in</tt><br>
<tt>question is being opened by about 100 processes/jobs at the same time.</tt><br>
<br>
<tt>Its a ~200GB file so copying the file locally first is not an easy</tt><br>
<tt>answer, and these jobs are causing issues with mmbackup scanning the</tt><br>
<tt>file system, in that the scan is taking 3 hours instead of the normal</tt><br>
<tt>40-60 minutes.</tt><br>
<br>
<tt>This is read only access to the file, I don't know the specifics about</tt><br>
<tt>the job.</tt><br>
<br>
<tt>It looks like the metanode is moving around a fair amount (given what I</tt><br>
<tt>can see from mmfsadm saferdump file)</tt><br>
<br>
<tt>I'm wondering if we there is anything we can do to improve things or</tt><br>
<tt>that can be tuned within GPFS, I'm don't think we have an issue with</tt><br>
<tt>token management, but would increasing maxFileToCache on our token</tt><br>
<tt>manager node help say?</tt><br>
<br>
<tt>Is there anything else I should look at, to try and attempt to allow</tt><br>
<tt>GPFS to share this file better.</tt><br>
<br>
<tt>Thanks in advance</tt><br>
<br>
<tt>Peter Childs</tt><br>
<br>
<tt>-- </tt><br>
<tt>Peter Childs</tt><br>
<tt>ITS Research Storage</tt><br>
<tt>Queen Mary, University of London</tt><br>
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