[Beowulf] noobs: what comes next?

Tomislav Maric tomislav.maric at gmx.com
Mon Jun 22 18:51:42 EDT 2009


I've sent this mail as a direct reply to Mr. John Hearns, so I'm sending
it again to the list - my apologies to Mr. Hearns.

Hearns, John wrote:
> >
> > I would guess you are looking are looking at using OpenFOAM for the CFD
> > solver?

Of course, what else is there? :))

> > One thing to look at though - how much RAM does each of these board
> > have?
> >

2GB 240-pin DIMM, unbuffered Non-ECC memory
> >
> > You might be better using the recipe for the cheap cluster on Doug
> > Eadlines Clustermonkey site.
> > http://www.clustermonkey.net//content/view/211/33/
> > By doing away with the cases they made a much cheaper cluster.

I've read both articles, for Microwulf and LunchBox. This is really a
great way to go, but I've done some numbers:

AMD Athlon 64 X2 2,66 GHz and ASUS mATX motherboard with GLAN and DDR2
RAM socket cost together about 170 USD.

and my original mboard with Atom CPU and 2GB DDR2 RAM costs about 120
USD. They are slower (1.66 GHz), but I'm worried about the power
consumption. The prices for miniITX are from here:

http://www.mini-box.com/Intel-D945GCLF2D-Mini-ITX-Motherboard

If I buy a 100 USD Gigabit switch, 3 HDDs (10000 RPM and about 160 GB)
and 10 of these motherboards, it would sum up to 1600 USD.

I'm just a huble noob. Please note that I'm just trying to find out
what's best for me, with no experience in price/performance ratios of
current COTS hardware or detailed knowledge of benchmarking.

> > If you use standard-sized motherboards you might get cheaper parts to
> > suit them,
> > And also have spare PCI clots for (say) a second gigabit network.
> >
> >

This might be a problem, but I can use my desktop comp for a master
node. I only have to buy additional Gig. Eth. NIC. That was our original
 idea.

> >
> > Pps. I hate to say this, but pragmatically with 6 of these boards you
> > get 12 times 1.6Ghz cores.
> > You can buy single workstations with eight cores of Nehalem at 2.6 Ghz
> > for not a lot of money.

The cheapest i7 i could find in Croatia is

Intel Core i7, 920, Socket 1366, 2.66GHz QuadCore and costs alone 400$.
To get the approx. configuration to the one above with miniITX, I would
have to by 2 of them on 2 motherboards costing about 300 USD each and
forcing me to pay additional 70 USD for DDR3 RAM.

This comes out about 1540 USD for this config with 4 GB RAM, and miniITX
combo has 10 GB. This is without the disks, the switch, two power
supplies and kablovinje (that's Croatian slang for cables  :) .

I'm also worried about the coarse grained nature of CFD simulations if I
go down this road - the IPC is really low with respect to RAM access and
data manipulation (again, I might be wrong, please correct me). Having 4
cores accessing 2GB of RAM all the time... can this be a problem?

> > You can still program these using MPI, and run Openfoam on them if your
> > aim really is to get runs done
> > For your MSc.
> > If on the other hand, you want to learn about clusters buy the boards
> > and let us know how it works!
> >
> >

I think I'll try and go with miniITX, this choice seems to be a blend of
coolness (I get to learn clustering) and it's cheap enough for a
graduate student from Croatia and his Highschool brother. :))

Thank You very much for the advice,

best regards,
Tomislav



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