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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Wanted to comment that we also hit this issue and agree with Paul that it would be nice in the FAQ to at least have something like the vertical bars that denote
changed or added lines in a document, which are seen in the GPFS Admin guides. This should make it easy to see what has changed.<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">Would also be nice to “Follow this page” to get notifications of when the FAQ changes from my IBM Knowledge Center account… or maybe the person that publishes
the changes could announce the update on the GPFS - Announce Developer Works page.<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"><a href="https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000001606">https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000001606</a>
<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">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-Bryan<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>Sanchez, Paul<br>
<b>Sent:</b> Friday, June 03, 2016 2:38 PM<br>
<b>To:</b> gpfsug main discussion list (gpfsug-discuss@spectrumscale.org) <gpfsug-discuss@spectrumscale.org><br>
<b>Subject:</b> [gpfsug-discuss] nosmap parameter for RHEL7 x86_64 on Haswell/Broadwell?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">After some puzzling debugging on our new Broadwell servers, all of which slowly became brick-like upon after getting stuck starting GPFS, we discovered that this was already
a known issue in the FAQ. Adding “nosmap” to the kernel command line in grub prevents SMAP from seeing the kernel-userspace memory interactions of GPFS as a reason to slowly grind all cores to a standstill, apparently spinning on stuck locks(?). (Big thanks
go to RedHat for turning us on to the answer when we opened a case.)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From
<a href="https://www.ibm.com/support/knowledgecenter/STXKQY/gpfsclustersfaq.html">
https://www.ibm.com/support/knowledgecenter/STXKQY/gpfsclustersfaq.html</a>, section 3.2:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <o:p></o:p></span></p>
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<p class="MsoNormal"><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Note: In order for IBM Spectrum Scale on RHEL 7 to run on the Haswell processor
</span></i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:0in;text-indent:-.25in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="font-size:10.0pt;font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Disable the Supervisor Mode Access Prevention (smap) kernel parameter</span></i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:0in;text-indent:-.25in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="font-size:10.0pt;font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Reboot the RHEL 7 node before using GPFS</span></i><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Some observations worth noting:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:0in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">We’ve been running for a year with Haswell processors and have hundreds of Haswell RHEL7 nodes which do not exhibit this problem. So maybe this only really affects
Broadwell CPUs?<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:0in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">It would be very nice for SpectrumScale to take a peek at /proc/cpuinfo and /proc/cmdline before starting up, and refuse to break the host when it has affected processors
and kernel without “nosmap”. Instead, an error message describing the fix would have made my day.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:0in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">I’m going to have to start using a script to diff the FAQ for these gotchas, unless anyone knows of a better way to subscribe just to updates to this doc.
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Thanks,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Paul Sanchez<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <o:p></o:p></span></p>
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