[Fwd: Re: 32-port gigabit switch]

[Dave Vehrs]

Rogerio,

If you do the math, you will find that Myrinet quickly becomes less
expensive than Gigabit as it scales to large node counts.  While Gigabit
PCI cards are inexpensive, Gigabit switches are not.  In our experience,
at ~64 nodes and above, Myrinet will be cheaper than Gigabit. 

Additionally the latency on Gigabit is simply to high for large
clusters.  Remember on clusters latency is more important than
throughput. 

If I was on a limited budget, I would checkout Ebay.  Recently, I've
seen several 16 port serial Myrinet switches with cables on sale for
$100-200 and PCI cards for $100-200 each.  While not quite cutting edge
it should allow you to get the cluster up and running, then later
upgrade to newer hardware.

Dave V.

On Wed, 2003-03-05 at 08:18, Rogerio Luiz Iope wrote:
> Hi all,
> 
> I'm in the early stages of building a 32-node beowulf
> cluster, and I'm looking for a really _low-cost_
> 32-port (or more) gigabit switch for the LAN interconnection.
> I was wondering if I could use e.g. Foundry EdgeIron
> model 24G. But in that case it would be necessary to use
> two of them because, as the name implies, it's a 24-port model.
> I suppose, however, that it's not a good idea to simply
> link-aggregate them, because in that case it would not be an
> interconnect topology with full bisection bandwidth.
> I was told about using the 'flat neighborhood network'
> topology as a cheap alternative, using three 24G switches and two
> NICs on each node, but I have no idea if it's a good solution or not,
> and I think it would be hard to configure and to scale.
> It's important to mention that the interconnect structure I'm looking for
> should be easy to scale, up to maybe 128 compute nodes or so,
> maintaining full bisection bandwidth. Oh, yeah, we have a very limited
> budget, so at the present moment, Myrinet is out of question.
> 
> I apologise if these are only simple questions, but I'm a newbie in the
> field, and I really need some help. I'd be glad to listen to the experts.
> 
> Thanks in advance,
> 
> Rogerio L. Iope
> University of Sao Paulo - Brazil
> phone: 55-11-3091-6461
> 
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-- 
David E Vehrs, System Engineer		Aspen Systems
davidv at aspsys.com			3900 Youngfield Street
Tel: +01 303 431 4606			Wheat Ridge CO 80033, USA
Fax: +01 303 431 7196			http://www.aspsys.com
-- 
David E Vehrs, System Engineer		Aspen Systems
davidv at aspsys.com			3900 Youngfield Street
Tel: +01 303 431 4606			Wheat Ridge CO 80033, USA
Fax: +01 303 431 7196			http://www.aspsys.com