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Hi Paul,<br>
<br>
Thanks, interestingly the FS-900 only does raid5. I get no choice about that, I do get a sector size choice when I create a lun on it...<br>
<br>
I was also wondering how gpfs would do a metadata update. Would it be smart enough to know the sector size was 512b and only modify that, or would it always do a read modify write on the whole 4k inode?<br>
<br>
Simon<br>
<br>
-----Original Message-----<br>
<b>From: </b>Sanchez, Paul [<a href="mailto:Paul.Sanchez@deshaw.com">Paul.Sanchez@deshaw.com</a>]<br>
<b>Sent: </b>Monday, May 16, 2016 10:28 AM GMT Standard Time<br>
<b>To: </b>gpfsug-discuss@spectrumscale.org<br>
<b>Subject: </b>Re: [gpfsug-discuss] Flash for metadata<br>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Simon,</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I can’t speak specifically to the FS-900, since I generally use Dell Compellent and NetApp EF arrays for flash today. But I also take care to ensure that the
system pool metadata NSDs use RAID10 (or equivalent) rather than RAID5/6. For small 4K metadata writes, on a 4K blocksize LUN this could result in optimal writes. For larger native blocksize LUNs, it eliminates the parity calculation for read-modify-write
operations. </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks,<br>
Paul</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b>
<span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">gpfsug-discuss-bounces@spectrumscale.org [mailto:gpfsug-discuss-bounces@spectrumscale.org]
<b>On Behalf Of</b> Simon Thompson (Research Computing - IT Services)<br>
<b>Sent:</b> Monday, May 16, 2016 9:44 AM<br>
<b>To:</b> gpfsug-discuss@spectrumscale.org<br>
<b>Subject:</b> [gpfsug-discuss] Flash for metadata</span></p>
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<p class="MsoNormal"> </p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Hi all</span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">I'm currently about to deploy some flash systems (FS-900) to take our metadata for one of our Spectrum Scale file-systems. We use 4k inodes for this file-system.</span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> </span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">On the FS-900, when creating a volume, we get a choice of 512b or 4k sectors. Does anyone have a suggestion on this? On a spinning disk RAID array, I get what
a strip size is and we'd use multiples of the stripe where possible for the block size.</span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> </span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Is the sector size on the FS-900 the smallest chunk that can be written out? And so would it make sense to use 4k sectors for 4k GPFS inodes right?</span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Related. In the deployment guide for the FS-900 arrays, if one is using a file-system (e.g. XFS) on the array the guide talks about aligning the partitions with
with array, when GPFS is used on a storage array, does it automatically work out the sector alignment?</span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> </span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Thanks</span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"> </span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Simon</span></p>
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