<div dir="ltr">We are in very similar situation.  VT - ARC has a layer of SSD for metadata only,  another layer of SSD for "hot" data, and a layer of 8TB HDDs for capacity.   We just now in the process of getting it all into production.<div><br></div><div>On this topic:</div><div><br></div><div>What is everyone's favorite migration policy to move data from SSD to HDD (and vice versa)?</div><div><br></div><div>Do you nightly move large/old files to HDD or wait until the fast tier hit some capacity limit?</div><div><br></div><div>Do you use QOS to limit the migration from SSD to HDD i.e. try not to kill the file system with migration work?</div><div><br></div><div><br></div><div>Thanks,</div><div>Brian Marshall</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Dec 15, 2016 at 4:25 PM, Buterbaugh, Kevin L <span dir="ltr"><<a href="mailto:Kevin.Buterbaugh@vanderbilt.edu" target="_blank">Kevin.Buterbaugh@vanderbilt.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">



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Hi Mark,
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<div>We just use an 8 Gb FC SAN.  For the data pool we typically have a dual active-active controller storage array fronting two big RAID 6 LUNs and 1 RAID 1 (for /home).  For the capacity pool, it might be the same exact model of controller, but the
 two controllers are now fronting that whole 60-bay array.</div>
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<div>But our users tend to have more modest performance needs than most…</div><span class="HOEnZb"><font color="#888888">
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<div>On Dec 15, 2016, at 3:19 PM, <a href="mailto:Mark.Bush@siriuscom.com" target="_blank">
Mark.Bush@siriuscom.com</a> wrote:</div>
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<span style="font-size:11pt;font-family:Calibri">Kevin, out of curiosity, what type of disk does your data pool use?  SAS or just some SAN attached system?<u></u><u></u></span></div>
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<b><span style="font-family:Calibri">From:<span class="m_-4095158022254147304Apple-converted-space"> </span></span></b><span style="font-family:Calibri"><<a href="mailto:gpfsug-discuss-bounces@spectrumscale.org" style="color:purple;text-decoration:underline" target="_blank">gpfsug-discuss-bounces@<wbr>spectrumscale.org</a>>
 on behalf of "Buterbaugh, Kevin L" <<a href="mailto:Kevin.Buterbaugh@Vanderbilt.Edu" style="color:purple;text-decoration:underline" target="_blank">Kevin.Buterbaugh@Vanderbilt.<wbr>Edu</a>><br>
<b>Reply-To:<span class="m_-4095158022254147304Apple-converted-space"> </span></b>gpfsug main discussion list <<a href="mailto:gpfsug-discuss@spectrumscale.org" style="color:purple;text-decoration:underline" target="_blank">gpfsug-discuss@spectrumscale.<wbr>org</a>><br>
<b>Date:<span class="m_-4095158022254147304Apple-converted-space"> </span></b>Thursday, December 15, 2016 at 2:47 PM<br>
<b>To:<span class="m_-4095158022254147304Apple-converted-space"> </span></b>gpfsug main discussion list <<a href="mailto:gpfsug-discuss@spectrumscale.org" style="color:purple;text-decoration:underline" target="_blank">gpfsug-discuss@spectrumscale.<wbr>org</a>><br>
<b>Subject:<span class="m_-4095158022254147304Apple-converted-space"> </span></b>Re: [gpfsug-discuss] Tiers<u></u><u></u></span></div>
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Hi Mark,<span class="m_-4095158022254147304Apple-converted-space"> </span><u></u><u></u></div>
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We’re a “traditional” university HPC center with a very untraditional policy on our scratch filesystem … we don’t purge it and we sell quota there.  Ultimately, a lot of that disk space is taken up by stuff that, let’s just say, isn’t exactly in active use.<u></u><u></u></div>
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So what we’ve done, for example, is buy a 60-bay storage array and stuff it with 8 TB drives.  It wouldn’t offer good enough performance for actively used files, but we use GPFS policies to migrate files to the “capacity” pool based on file atime.  So we have
 3 pools:<u></u><u></u></div>
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1.  the system pool with metadata only (on SSDs)<u></u><u></u></div>
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2.  the data pool, which is where actively used files are stored and which offers decent performance<u></u><u></u></div>
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3.  the capacity pool, for data which hasn’t been accessed “recently”, and which is on slower storage<u></u><u></u></div>
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I would imagine others do similar things.  HTHAL…<u></u><u></u></div>
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Kevin<u></u><u></u></div>
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On Dec 15, 2016, at 2:32 PM,<span class="m_-4095158022254147304Apple-converted-space"> </span><a href="mailto:Mark.Bush@siriuscom.com" style="color:purple;text-decoration:underline" target="_blank">Mark.Bush@siriuscom.com</a><span class="m_-4095158022254147304Apple-converted-space"> </span>wr<wbr>ote:<u></u><u></u></div>
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<span style="font-size:11pt;font-family:Calibri">Just curious how many of you out there deploy SS with various tiers?  It seems like a lot are doing the system pool with SSD’s but do you routinely have clusters that have more than system pool and
 one more tier? <span class="m_-4095158022254147304apple-converted-space"> </span></span><span style="font-family:Calibri"><u></u><u></u></span></div>
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<span style="font-size:11pt;font-family:Calibri">I know if you are doing Archive in connection that’s an obvious choice for another tier but I’m struggling with knowing why someone needs more than two tiers really.</span><span style="font-family:Calibri"><u></u><u></u></span></div>
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<span style="font-size:11pt;font-family:Calibri">I’ve read all the fine manuals as to how to do such a thing and some of the marketing as to maybe why.  I’m still scratching my head on this though.  In fact, my understanding is in the ESS there
 isn’t any different pools (tiers) as it’s all NL-SAS or SSD (DF150, etc).<span class="m_-4095158022254147304apple-converted-space"> </span></span><span style="font-family:Calibri"><u></u><u></u></span></div>
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<span style="font-size:11pt;font-family:Calibri">It does make sense to me know with TCT and I could create an ILM policy to get some of my data into the cloud.</span><span style="font-family:Calibri"><u></u><u></u></span></div>
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<span style="font-size:11pt;font-family:Calibri">But in the real world I would like to know what yall do in this regard.</span><span style="font-family:Calibri"><u></u><u></u></span></div>
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<span style="font-size:11pt;font-family:Calibri">Thanks</span><span style="font-family:Calibri"><u></u><u></u></span></div>
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<span style="font-size:11pt;font-family:Calibri">Mark<span class="m_-4095158022254147304apple-converted-space"> </span></span><span style="font-family:Calibri"><u></u><u></u></span></div>
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