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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">What version of GPFS are you running Keith?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">All nodes mounting the file system must briefly quiesce I/O operations during the snapshot create operations, hence the “</span><span style="font-size:9.0pt;font-family:BookMaster">Quiescing
all file system operations.</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">” message in the output. So don’t really see a way to specify a specific set of nodes for these operations. They have made updates in newer releases
of GPFS to combine operations (e.g. create and delete snapshots at the same time) which IBM says “system performance is increased by batching operations and reducing overhead.”.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Trying to isolate GPFS resources (e.g. cgroups) on the clients (e.g. CPU and memory resources dedicated to GPFS/SSH/kernel/networking/etc) can help them respond
more quickly to quiesce I/O requests.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">HTH,<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>
<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>Keith Ball<br>
<b>Sent:</b> Tuesday, March 27, 2018 5:26 PM<br>
<b>To:</b> gpfsug-discuss@spectrumscale.org<br>
<b>Subject:</b> [gpfsug-discuss] Control of where mmcrsnapshot runs?<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><em><span style="font-size:8.5pt;font-family:"Verdana",sans-serif;color:#333333">Note: External Email</span></em><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi All,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Two questions on snapshots:<o:p></o:p></p>
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<p class="MsoNormal">1.) I note that neither "mmcrsnapshot" nor "mmdelsnapshot" appear to have an "-N" option as "PIT" commands typically do. Is there any way to control where threads for snapshot creation/deletion run? (I assume the filesystem manager will
always be involved regardless).<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">2.) When mmdelsnapshot hangs or times out, the error messages tend to appear on client nodes, and not necessarily the node where mmdelsnapshot is run from, not the FS manager. Besides telling all users "don't
use any I/O" when runnign these commands, are there ways that folks have found to avoid hangs and timeouts of mmdelsnapshot?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">FWIW our filesystem manager is probably overextended (replication factor 2 on data+MD, 30 daily snapshots kept, a number of client clusters served, plus the FS manager is also an NSD server).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Many Thanks,<o:p></o:p></p>
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<p class="MsoNormal"> Keith<o:p></o:p></p>
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<p class="MsoNormal">RedLine Performance Solutions LLC <o:p></o:p></p>
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