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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">Hi Shankar, Vic,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Would it not be possible, once the original cache site is useable, to bring it up in local-update mode so that you can pre-fetch all
the metadata from home?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Once you are ready to do the switchover: stop writing to home, do a final sync of metadata, then “promote” the local-update cache to
a single-writer; continue writing new data in to the original cache.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">I am assuming the only reason you’d want to repopulate the SW cache with metadata is to prevent someone accidentally creating the same
file after the disaster and overwriting the original at home without any knowledge?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Luke.<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></a></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>Shankar Balasubramanian<br>
<b>Sent:</b> 19 April 2016 06:47<br>
<b>To:</b> gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>
<b>Subject:</b> Re: [gpfsug-discuss] AFM Question<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">SW mode does not support failover. IW does, so this will not work.
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<span style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
<br>
Best Regards,<br>
Shankar Balasubramanian<br>
AFM & Async DR Development<br>
IBM Systems<br>
Bangalore - Embassy Golf Links <br>
India<br>
<br>
</span><br>
<br>
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<span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#5F5F5F">From: </span><span style="font-size:7.5pt;font-family:"Arial",sans-serif">Vic Cornell <<a href="mailto:viccornell@gmail.com">viccornell@gmail.com</a>></span><br>
<span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#5F5F5F">To: </span><span style="font-size:7.5pt;font-family:"Arial",sans-serif">gpfsug main discussion list <<a href="mailto:gpfsug-discuss@spectrumscale.org">gpfsug-discuss@spectrumscale.org</a>></span><br>
<span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#5F5F5F">Date: </span><span style="font-size:7.5pt;font-family:"Arial",sans-serif">04/18/2016 07:13 PM</span><br>
<span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#5F5F5F">Subject: </span><span style="font-size:7.5pt;font-family:"Arial",sans-serif">[gpfsug-discuss] AFM Question</span><br>
<span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#5F5F5F">Sent by: </span><span style="font-size:7.5pt;font-family:"Arial",sans-serif"><a href="mailto:gpfsug-discuss-bounces@spectrumscale.org">gpfsug-discuss-bounces@spectrumscale.org</a></span><o:p></o:p></p>
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Hi All,<o:p></o:p></p>
<p>Is there a bandwidth efficient way (downtime is allowed) to reverse the relationship between HOME and CACHE in a single writer AFM relationship?<o:p></o:p></p>
<p>If it is not immediately obvious why this might be useful, see the following scenario:<o:p></o:p></p>
<p>Fileset A is a GPFS fileset which is acting as CACHE for a single writer HOME on fileset B located on a separate filesystem.<o:p></o:p></p>
<p>The system hosting A fails and all data on fileset A is lost.<o:p></o:p></p>
<p>Admin uses fileset B as a recovery volume and users read and write data to B until the system hosting A is recovered, albeit without data.<o:p></o:p></p>
<p>Admin uses mmafmctl to “failover” AFM relationship to a new fileset on A, all data are copied from B to A over time and users continue to access the data via B.<o:p></o:p></p>
<p>So is there a bandwidth efficient way (downtime is allowed) to reverse the relationship between A and B such that the replication flow is as it was to start with?<o:p></o:p></p>
<p>Cheers,<o:p></o:p></p>
<p style="margin-bottom:12.0pt">Vic<br>
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<br>
</span><o:p></o:p></p>
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