<div class="socmaildefaultfont" dir="ltr" style="font-family:Arial, Helvetica, sans-serif;font-size:10.5pt" ><div dir="ltr" >Aaron,</div>
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<div dir="ltr" >Also are your new NSDs the same size as your existing ones?</div>
<div dir="ltr" >i.e. the NSDs that are at a higher %age full might have more free blocks than the other NSDs?</div>
<div dir="ltr" ><div class="socmaildefaultfont" dir="ltr" style="font-family:Arial, Helvetica, sans-serif;font-size:10.5pt" ><div class="socmaildefaultfont" dir="ltr" style="font-family:Arial, Helvetica, sans-serif;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 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:1.286em;" ><span style="font-family: Verdana,Geneva,sans-serif;" >Daniel</span></span></div>
<div style="margin-bottom:0cm;margin-bottom:.0001pt;line-height:normal;" ><br> </div>
<table border="0" cellpadding="0" cellspacing="0" > <tbody> <tr> <td style="width: 150px; padding: 0cm;" > <div style="margin-bottom:0cm;margin-bottom:.0001pt;line-height:normal;" ><a href="https://www.youracclaim.com/user/danel-kidger" target="_blank" ><img alt="IBM Storage Professional Badge" src="" src="https://acclaim-production-app.s3.amazonaws.com/images/ea52b12f-97ac-4e72-8d24-b0ced8054e7d/Storage%2BTechnical%2BV1.png" style="width: 120px; height: 120px; float: left;" ></a></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 face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2" > </font></div></div></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: Jan-Frode Myklebust <janfrode@tanso.net><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] pool block allocation algorithm<br>Date: Sat, Jan 13, 2018 9:25 AM<br> <br>Don’t have documentation/whitepaper, but as I recall, it will first allocate round-robin over failureGroup, then round-robin over nsdServers, and then round-robin over volumes. So if these new NSDs are defined as different failureGroup from the old disks, that might explain it..<br><br><br>-jf
<div><div dir="ltr" >lør. 13. jan. 2018 kl. 00:15 skrev Aaron Knister <<a href="mailto:aaron.s.knister@nasa.gov" target="_blank" >aaron.s.knister@nasa.gov</a>>:</div>
<blockquote style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex" >Apologies if this has been covered elsewhere (I couldn't find it if it<br>has). I'm curious how GPFS decides where to allocate new blocks.<br><br>We've got a filesystem that we added some NSDs to a while back and it<br>hurt there for a little while because it appeared as though GPFS was<br>choosing to allocate new blocks much more frequently on the ~100% free<br>LUNs than the existing LUNs (I can't recall how free they were at the<br>time). Looking at it now, though, it seems GPFS is doing the opposite.<br>There's now a ~10% difference between the LUNs added and the existing<br>LUNs (20% free vs 30% free) and GPFS is choosing to allocate new writes<br>at a ratio of about 3:1 on the disks with *fewer* free blocks than on<br>the disks with more free blocks. That's completely inconsistent with<br>what we saw when we initially added the disks which makes me wonder how<br>GPFS is choosing to allocate new blocks (other than the obvious bits<br>about failure group, and replication factor). Could someone explain (or<br>point me at a whitepaper) what factors GPFS uses when allocating blocks,<br>particularly as it pertains to choosing one NSD over another within the<br>same failure group.<br><br>Thanks!<br><br>-Aaron<br><br>--<br>Aaron Knister<br>NASA Center for Climate Simulation (Code 606.2)<br>Goddard Space Flight Center<br>(301) 286-2776<br>_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__spectrumscale.org&d=DwMFaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=HlQDuUjgJx4p54QzcXd0_zTwf4Cr2t3NINalNhLTA2E&m=f89xvht1uMUzAcLpusakZb1snMOgweGu0KTkKp9oedI&s=QYsXVDOdNRcII7FPtAbCXEyYJzNSd_UXq8bmreALKxs&e=" rel="noreferrer" target="_blank" >spectrumscale.org</a><br><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__gpfsug.org_mailman_listinfo_gpfsug-2Ddiscuss&d=DwMFaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=HlQDuUjgJx4p54QzcXd0_zTwf4Cr2t3NINalNhLTA2E&m=f89xvht1uMUzAcLpusakZb1snMOgweGu0KTkKp9oedI&s=NSd3e2hwIKBCwSxsKe-GTf8EwJ6AkZQiTsRQZ73UH20&e=" rel="noreferrer" target="_blank" >http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a></blockquote></div>
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