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Re: fyi (fwd)
Hashibon Adham wrote:
>
> Hi all,
>
> Enjoy :-)
> ---------- Forwarded message ----------
[snip]
> A basic entry-level system begins at just under $3,000 while a fully
> configured 16 Node Cluster is being offered for under $15,000. The new
> 16-node system being demonstrated at the Linux Expo is performing an
> industry-recognized test in approximately 12 seconds compared to the Cray
> T3-E's performance of 3 seconds, which has a cost of $5,500,000.
[snip]
I'm far from being an expert in supercomputers, but the above seems
questionable. A few points to ponder:
a. The Cray T3E is an MPP (Massively Parallel Processor), while a
Beowulf cluster isn't (and doesn't claim to be). An essential difference
is that a Beowulf cluster has significantly higher interprocessor
communication latency and significantly lower bandwidth, which renders
it unsuitable for some applications. The exact figures depend on EBIZ's
hardware, of course, but we're probably talking about orders of
magnitude: MPPs use exotic hardware and esoteric architectures to tweak
the above parameters up to pretty amazing numbers, while EBIZ presumably
just tucked in a Fast Ethernet switch.
b. "an industry-recognized test"? What would this be, ZDNet WinBench?
I'd bet my lunch they used a test that gives very little weight to
interprocessor communication, which is half the fun in a supercomputer.
If they just count CPU cycles on each node and sum them up, then the
figure is (1) unimpressive and (b) far from reflecting practical use.
c. About the Cray T3E costing $5,500,000: which T3E is it, the T3E-900
or T3E-1200? With how many processors, from the possible range of 6 to
*2048*? Is this the same model they benchmarked as only 4 times faster
than their cluster? If not, than the comparison is misleading. If it
/is/, then it's like arming a battle tank with paintballs and then
claiming an
assault rifle is more effective.
d. One could go on about scalability (16 vs. 2048 processors), I/O
bandwidth (128GB/sec for the T3E-1200) et cetera, but they didn't make
any claims about this, so.
Now, Beowulf is an important technology with quite a few applications,
and a Good Thing in general. However, EBIZ's claims as reflected by
their press release demonstrate more marketoid agitation than technical
competence.
Regards,
Eran Tromer
- References:
- fyi (fwd)
- From: Hashibon Adham <phadham@aluf.technion.ac.il>