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Selecting Computing Hardware for CFD Research?
bapya asks: "I am a
PhD student working on CFD ? at National Chemical Laboratory, India.
We mainly use commercial CFD code (Fluent from
Fluent Inc.) and some inhouse
codes. Currently we use SGI machines (Origin 200 and O2 family running
IRIX), single and dual processor NT machines, DEC alpha and dual
processor Linux (running RH 6.2) machines. Now we are planning to
upgrade/expand our computational facilities. For the same amount of
money (about 25000$), we can buy either a decent unix(IRIX) server
(origin 200 dual cpu) or build a much better performing Intel system
(either NT or Linux). My professor is in favor of IRIX system. What
I would like to ask is what are the criteria for selecting hardware
for such a job? and How can one justify the high prices of
branded UNIX systems when other systems of same performance level
can be built at much lesser costs?"
Although I have no idea what it is your researching, or even what all thoes TLA's mean, I can still provide you with a little recommendation.
:P
SGI/IRIX in my experince is great for crunching numbers, we have an Origin 200 dual CPU with a gig and a half of ram supporting the load of 3 full time 3d designers. Granted SGI has the advantage in the graphics arena, but in our situation the rendering aspect is handed off to x86 workstations (but thats a whole other ball of wax)
One other thing to consider is SGI's wonderful support. We recently had a failure that crashed the server, SGIs ESP program notified them of the crash, and within a few minutes a tech had called us to schedule a service guy to come out and replace our motherboard/ram/cpu with all brand new equipment. Since we're an out of the way town, the soonest we could get is the next day.
On a side note, from what our service tech was saying most of @Home's customer proxy servers are(used to be) Origin 200's.
If you do choose to go the IRIX route, you might look into the Origin 300 line, from what I hear its supposed to be the next step for the 200 series.
If you are still considering, and need any real-life experince feedback or have any questions, drop me an email.
symetrix. We are building a religion, a limited edition.
Seriously though, it is easy to take a good parallel code and murder it by going for a Beowulf option. I assume that your CFD code is a heavilly parallel beast. From what I have seen from the links available here one must be very careful about the relative importance of the node communication bandwidth and the node latency on the code in question.
In my opinion this decision boils down to the following:
How interdependent is the parallel code? If the code is trivially parallel, as many of mine are, then a cluster of the cheapest ix86 machines running Linux is an excellent bet.
Are you certain that the code will work on the platforms in question? Perhaps invest a couple of kiloquid (thousand pounds) or so in a few ix86 machines for a feasibility study, if it doesn't then you have cut your losses and have a few machines to play Quake on ;-). For the ultra cheap option, if your Prof is unhappy about gambing any dosh (money) on buying new stuff, stick Linux on the NT machines and try those.
How far through your PhD are you? Quite seriously, if you're anything like me you may find that you end up spending most of your time tweaking computers rather than doing physics. Building your own supercomputer could easilly suck your entire PhD down the time toilet.
I expect you have done this already but ask the people at Fluent Inc. what experience they have on parallelizing their codes.
Finally, I would say while the support you may get from commercial *NIX vendors is generally good it can also be very expensive. While this is not necessarilly a problem in a commercial datacentre environment, in academia it can be crippling. If you and your co-workers are willing to expend time and effort into trying to get the code working on a Beowulf style cluster it could well be a good long term investment.
Good luck!
P.S. When I checked this post, www.beowulf.org was down so you may want to check the google cache.
-edBe nice to people on the way up. You will meet them again on your way down!