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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I think the change in scale over the past 10-15 years is interesting, and especially the changes in architecture that result from this.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Going from 8-16 processors to 1000s is a big change. Bisection bandwidth on your comm fabric. How do you boot.. 8 processors can be booted sequentially or
simultaneously from a server. For 1000 you need a “better way”. How do you feed files to/from a 1000 processor cluster?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Issues with checkpoint/restart/reliability. We had a project here at JPL looking at replacing the big 70 meter dishes with an array of, say, 100 6-12 meter
dishes. Replacing the single custom box with lots of a commodity things (6-12 meter antennas are stamped out by the hundreds). Very Beowulf’y in concept.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Turns out that cryocolers (needed to keep the receiver at a nice toasty 4 Kelvins) aren’t really a mass produced item, and at the observed failure rates, you’d
have a hard time keeping enough of them working to do what you needed. A failure rate of once a month (or something.. I don’t know what the actual rates are) on the 70m antenna means you can have a spare and swap it in, and then you basically have a month
to fix the broken one. With 100 antennas and a cryocooler MTBF of 0.5 years, you’ll have 4 broken coolers at any given time<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The practical differences in experience between assembling a toy cluster of 4-8 processors and simulating it with VM instances on a single machine. What you
learn from the former that you don’t get on the latter (the importance of labeling of cables, for instance).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Jim Lux<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<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""> beowulf-bounces@beowulf.org [mailto:beowulf-bounces@beowulf.org]
<b>On Behalf Of </b>Andrew Holway<br>
<b>Sent:</b> Sunday, March 03, 2013 12:24 AM<br>
<b>To:</b> Bewoulf<br>
<b>Subject:</b> [Beowulf] Themes for a talk on beowulf clustering<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hello all, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I am giving a talk on beowulf clustering to a local lug and was wondering if you had some interesting themes that I could talk about.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">ta for now.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Andrew<o:p></o:p></p>
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