<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Hi</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">I'll give my opinion. Worth what you pay for. </div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">Do as many as you can, six in this case for the good reason you mentioned. </div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">But play with the callbacks so the migration happens on watermarks when it happens. Otherwise you might hit no space till your next policy run. </div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">The second is well documented on the redbook AFAIK</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">Cheers<br><br>--<div>Cheers</div></div><div><br>On 19 Apr 2017, at 22.54, Buterbaugh, Kevin L <<a href="mailto:Kevin.Buterbaugh@Vanderbilt.Edu">Kevin.Buterbaugh@Vanderbilt.Edu</a>> wrote:<br><br></div><blockquote type="cite"><div>
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Hi All,
<div class=""><br class=""></div><div class="">We currently have what I believe is a fairly typical setup … metadata for our GPFS filesystems is the only thing in the system pool and it’s on SSD, while data is on spinning disk (RAID 6 LUNs). Everything connected via 8 Gb FC SAN. 8 NSD servers.
Roughly 1 PB usable space.</div><div class=""><br class=""></div><div class="">Now lets just say that you have a little bit of money to spend. Your I/O demands aren’t great - in fact, they’re way on the low end … typical (cumulative) usage is 200 - 600 MB/sec read, less than that for writes. But while GPFS has always been
great and therefore you don’t need to Make GPFS Great Again, you do want to provide your users with the best possible environment.</div><div class=""><br class=""></div><div class="">So you’re considering the purchase of a dual-controller FC storage array with 12 or so 1.8 TB SSD’s in it, with the idea being that that storage would be in its’ own storage pool and that pool would be the default location for I/O for your main
filesystem … at least for smaller files. You intend to use mmapplypolicy nightly to move data to / from this pool and the spinning disk pools.</div><div class=""><br class=""></div><div class="">Given all that … would you configure those disks as 6 RAID 1 mirrors and have 6 different primary NSD servers or would it be feasible to configure one big RAID 6 LUN? I’m thinking the latter is not a good idea as there could only be one primary
NSD server for that one LUN, but given that: 1) I have no experience with this, and 2) I have been wrong once or twice before (<grin>), I’m looking for advice. Thanks!</div><div class=""><br class=""></div><div class=""><div class=""><div class="">—</div><div class="">Kevin Buterbaugh - Senior System Administrator</div><div class="">Vanderbilt University - Advanced Computing Center for Research and Education</div><div class=""><a href="mailto:Kevin.Buterbaugh@vanderbilt.edu" class="">Kevin.Buterbaugh@vanderbilt.edu</a> - (615)875-9633</div><div class=""><br class=""></div><br class="Apple-interchange-newline"></div><br class=""></div>
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