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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Embarrassingly I don’t know how to do that scientifically. I can tell you latency of the storage system which at a very simplistic
snapshot is averaging around 2ms. We are not using SSD for metadata but 10K SAS.<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" 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>J. Eric Wonderley<br>
<b>Sent:</b> 22 March 2017 13:41<br>
<b>To:</b> gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Subject:</b> Re: [gpfsug-discuss] snapshots & tiering in a busy filesystem<o:p></o:p></span></p>
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<p class="MsoNormal">The filesystem I'm working with has about 100M files and 80Tb of data.<br>
<br>
What kind of metadata latency do you observe?<br>
I did a mmdiag --iohist and filtered out all of the md devices and averaged over reads and writes. I'm seeing ~.28ms on a one off dump. The pure array which we have is 10G iscsi connected and is reporting average .25ms.<o:p></o:p></p>
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<p class="MsoNormal">On Wed, Mar 22, 2017 at 6:47 AM, Sobey, Richard A <<a href="mailto:r.sobey@imperial.ac.uk" target="_blank">r.sobey@imperial.ac.uk</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">We’re also snapshotting 4 times a day. Filesystem isn’t tremendously busy at all but we’re creating
snaps for each fileset.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">[root@cesnode tmp]# mmlssnapshot gpfs | wc -l</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">6916</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">
<a href="mailto:gpfsug-discuss-bounces@spectrumscale.org" target="_blank">gpfsug-discuss-bounces@spectrumscale.org</a> [mailto:<a href="mailto:gpfsug-discuss-bounces@spectrumscale.org" target="_blank">gpfsug-discuss-bounces@spectrumscale.org</a>]
<b>On Behalf Of </b>J. Eric Wonderley<br>
<b>Sent:</b> 20 March 2017 14:03<br>
<b>To:</b> gpfsug main discussion list <<a href="mailto:gpfsug-discuss@spectrumscale.org" target="_blank">gpfsug-discuss@spectrumscale.org</a>><br>
<b>Subject:</b> [gpfsug-discuss] snapshots & tiering in a busy filesystem</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I found this link and it didn't give me much hope for doing snapshots & backup in a home(busy) filesystem:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:12.0pt"><a href="http://www.spectrumscale.org/pipermail/gpfsug-discuss/2013-February/000200.html" target="_blank">http://www.spectrumscale.org/pipermail/gpfsug-discuss/2013-February/000200.html</a><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I realize this is dated and I wondered if qos etc have made is a tolerable thing to do now. Gpfs I think was barely above v3.5 in mid 2013.<o:p></o:p></p>
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_______________________________________________<br>
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gpfsug-discuss at <a href="http://spectrumscale.org" target="_blank">spectrumscale.org</a><br>
<a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss" target="_blank">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a><o:p></o:p></p>
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