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<div dir="ltr" >If you need functionality like you describe, then as well as using tiering with the ILM Policy Engine, also consider using AFM to cache onto say SSDs. That way you would have dynamic caching: as soon as a file gets accessed, it goes into the cache and further I/O will be do the SSD copy so faster until such time as the file ages and newer files replace it in the AFM cache. The cost of this is perhaps a little more complexity and also a 'hot' file consumes space on both SSD and disk.</div>
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<div dir="ltr" ><div class="socmaildefaultfont" dir="ltr" style="font-family:Arial;font-size:10.5pt" ><div class="socmaildefaultfont" dir="ltr" style="font-family:Arial;font-size:10.5pt" ><div class="socmaildefaultfont" dir="ltr" style="font-family: Arial; font-size: 10.5pt;" ><div class="socmaildefaultfont" dir="ltr" style="font-family: Arial; font-size: 10.5pt;" ><div class="socmaildefaultfont" dir="ltr" style="font-family: Arial; font-size: 10.5pt;" ><div class="socmaildefaultfont" dir="ltr" style="font-family: Arial; font-size: 10.5pt;" ><div class="socmaildefaultfont" dir="ltr" style="font-family: Arial; font-size: 10.5pt;" ><div class="socmaildefaultfont" dir="ltr" style="font-family: Arial; font-size: 10.5pt;" ><div dir="ltr" style="margin-top: 20px;" ><div style="font-family: sans-serif; font-size: 8pt; margin-top: 10px;" ><div style="margin-bottom:0cm;margin-bottom:.0001pt;line-height:normal;" ><span style="font-size:1.143em;" ><span style="font-family: Verdana,Geneva,sans-serif;" >Daniel</span></span></div>
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<div style="margin-bottom:0cm;margin-bottom:.0001pt;line-height:normal;" > v<br> </div>
<table cellpadding="0" cellspacing="0" border="0" > <tbody> <tr> <td style="width:201px;padding:0cm 0cm 0cm 0cm;" > <div style="margin-bottom:0cm;margin-bottom:.0001pt;line-height:normal;" ><img alt="Spectrum Scale Logo" src="" src="http://ausgsa.ibm.com/projects/t/tivoli_visual_design/public/2015/Spectrum-Storage/Email-signatures/Storage/spectrum_scale-logo.png" style="width: 75px; height: 120px; float: left;" ></div>
<div style="margin-bottom:0cm;margin-bottom:.0001pt;line-height:normal;" > </div> </td> <td style="width:21px;padding:0cm 0cm 0cm 0cm;" > </td> <td style="width:202px;padding:0cm 0cm 0cm 0cm;" > <div style="margin-bottom:0cm;margin-bottom:.0001pt;line-height:normal;" ><strong><span style="font-family:Arial, Helvetica, sans-serif" ><span style="font-size:10.0pt;" >Dr Daniel Kidger</span></span></strong><br> <span style="font-family:Arial, Helvetica, sans-serif" ><span style="font-size:7.5pt;" >IBM Technical Sales Specialist<br> Software Defined Solution Sales<br> <br> +</span></span><span style="color:#5F5F5F;" ><span style="font-family:Verdana, Geneva, sans-serif" ><span style="font-size:10.0pt;" >44-(0)7818 522 266 </span></span></span><br> <span style="color:#5F5F5F;" ><span style="font-family:Arial, Helvetica, sans-serif" ><span style="font-size:8.0pt;" >daniel.kidger@uk.ibm.com</span></span></span></div> </td> </tr> </tbody></table><font size="2" face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" > </font></div></div></div></div></div></div></div></div></div></div></div>
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<blockquote data-history-content-modified="1" dir="ltr" style="border-left:solid #aaaaaa 2px; margin-left:5px; padding-left:5px; direction:ltr; margin-right:0px" >----- Original message -----<br>From: Eric Horst <erich@uw.edu><br>Sent by: gpfsug-discuss-bounces@spectrumscale.org<br>To: gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>Cc:<br>Subject: Re: [gpfsug-discuss] File_heat for GPFS File Systems<br>Date: Tue, Sep 27, 2016 9:56 PM<br>
<div><font size="2" face="Default Monospace,Courier New,Courier,monospace" >>><br>>> if a file gets hot again, there is no rule for putting the file back<br>>> into a faster storage device?<br>><br>><br>> The file will get moved when you run the policy again. You can run the<br>> policy as often as you like.<br><br>I think its worth stating clearly that if a file is in the Thrifty<br>slow pool and a user opens and reads/writes the file there is nothing<br>that moves this file to a different tier. A policy run is the only<br>action that relocates files. So if you apply the policy daily and over<br>the course of the day users access many cold files, the performance<br>accessing those cold files may not be ideal until the next day when<br>they are repacked by heat. A file is not automatically moved to the<br>fast tier on access read or write. I mention this because this aspect<br>of tiering was not immediately clear from the docs when I was a<br>neophyte GPFS admin and I had to learn by observation. It is easy for<br>one to make an assumption that it is a more dynamic tiering system<br>than it is.<br><br>-Eric<br><br>--<br>Eric Horst<br>University of Washington<br>_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss" target="_blank" >http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a></font><br> </div></blockquote>
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