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<p class="MsoNormal">Right, except I should point out that a mirror sync operation doesn’t have to be from one pool to another. The FLR replica can use any specified layout. Using an OST Pool is just a convenience.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">-Cory<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">On 2/20/21, 12:10 PM, "Indivar Nair" <indivar.nair@techterra.in> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Thanks, Cory.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">So -<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">1. When the "lfs mirror" command is run, the file(s) are copied by the client from one pool to another<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> Pool A -> Client Machine -> Pool B (mirror)<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">2. If a mirrored file is modified, the modifications are saved only to the primary mirror<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> We will then have to run the "lfs mirror resync" command to synchronize all the mirror copies<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> Pool A (modified file) -> Client Machine -> Pool B (mirror)<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">So for this feature to be really effective, we will need a dedicated client that does this copying / re-copying continuously.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">And if there are a lot of mirrored files, the dedicated client will have to be very fast too.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">3. In future it may be possible to move these files using HSM agents.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Regards,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Indivar Nair<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">On Fri, Feb 19, 2021 at 1:51 AM Spitz, Cory James <<a href="mailto:cory.spitz@hpe.com" target="_blank">cory.spitz@hpe.com</a>> wrote:<o:p></o:p></p>
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Good questions, Indivar.<o:p></o:p></p>
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1) The Lustre Operations Manual doesn’t make this clear at <a href="https://doc.lustre.org/lustre_manual.xhtml#flr.operations.resyncmirror" target="_blank">https://doc.lustre.org/lustre_manual.xhtml#flr.operations.resyncmirror</a> , but a mirror sync will be completed in the context of the client that it was executed on.
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2) Mirror resync is entirely manual today. Again, it is done in the context of the client from which the lfs command was executed. Automatic or “Immediate” mirror is on the
<a href="https://www.lustre.org/roadmap/" target="_blank">https://www.lustre.org/roadmap/</a> for 2.16.0. However, as a side note, there are also plans to “externalize” and leverage the HSM coordinator to be able to hand-off the data movement to multiple data movers. See LU-6081, LU-12890, and LU-13384 for an outline
of that work. I only mention it here because you’ve hinted at the need for this improvement, but it is not committed to the roadmap yet.<o:p></o:p></p>
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3) One way could use lfs find to find files needing a mirror update. There are multiple options to zero in on the mirror count and/or state. Consult the lfs-find man page for details.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
-Cory<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
On 2/17/21, 6:43 AM, "lustre-discuss" <<a href="mailto:lustre-discuss-bounces@lists.lustre.org" target="_blank">lustre-discuss-bounces@lists.lustre.org</a>> wrote:<o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
Hi All,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
I was going through the FLR feature in the Lustre Manual and had some questions.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
1. If we run the "lfs mirror" command on an existing file or directory, how is the file ' directory copied from one OST to another?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
Is the copying done by the Lustre client on which this command was run?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
2. And, in case of delayed mirroring of newly created files, who does the copying?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
3. How can we automate this process to automatically mirror certain file types?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
Regards,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.0in">
Indivar Nair<o:p></o:p></p>
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