Hey Jon,
Fun to see you here!! I was just looking through some old Goleta pictures
last week.
Just for kicks have a look at these figures:
http://www.lsc-group.phys.uwm.edu/beowulf/nemo/design/SMC_8508T_Performance.html
This was part of a study that we did to select edge switches for the NEMO
cluster. We were able to find sub-$100 switches that were wire speed up
to MTUs of about 6k.
There was a big difference between similar looking cheap switches from
various companies. And indeed, 'under the hood' they all used integrated
chip sets from a handful of chip vendors.
Here are some more testing results from different edge switches:
http://www.lsc-group.phys.uwm.edu/beowulf/nemo/design/switching.html
(Note: our processing is embarassingly parallel, so we are primarily
building compute farms. We don't need very high bandwidth very low
latency connections, eg infiniband or myrinet performance.)
Cheers,
Bruce
On Sun, 1 Apr 2007, Jon Forrest wrote:
Douglas Eadline wrote:
<Soapbox>
I am constantly amazed at how many people buy the
latest and greatest node hardware and then connect
them with a sub-optimal switch (or cheap cables), thus reducing
the effective performance of the nodes (for parallel
applications). Kind "penny wise and pound foolish" as they say.
</Soapbox>
I sincerely appreciate all the comments about my problem. I will reply
to them in due time. However, I'd like to comment on this, which
admittedly is off-topic from my original posting.
I don't disagree with what you're saying. The problem is how
to recognize "sub-optimal" equipment. For example, I see
three tiers in ethernet switching hardware:
1) The low-end, e.g. Netgear, Linksys, D-link, ...
2) The mid-end, e.g. HP Procurve, Dell, SMC, ...
3) The high-end, e.g. Cisco, Foundry, ...
What I, as a system manager, not as an Electrical Engineer,
have trouble understanding, is what the true differences
are between these levels, and, at one level, between
the various vendors.
These days I suspect that many of the vendors are using
ASICs made by other chip companies, and the many vendors
use the same ASICs. Assuming that's true, where's the
added value that justifies the cost differences? Sometimes
the value is in the "management" abilities of a device.
I don't deny this can be a major selling point in a
large enterprise environment, but in a 30-node cluster,
or a small LAN, it's hard to justify paying for this.
In terms of ethernet performance, once a device
can handle wirespeed communication on all ports,
where's the added value that justifies the added
cost? I'm looking for empirical answers, which
aren't always easy to find, and sometimes to understand.
In the case of my cluser, it was configured and purchased
before I got here, so I had nothing to do with choosing
its components but I have to admit that I'm not
sure what I would have done differently.
Cordially,
Jon Forrest
Unix Computing Support
College of Chemistry
173 Tan Hall
University of California Berkeley
Berkeley, CA
94720-1460
510-643-1032
[EMAIL PROTECTED]
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