Hi,
just some remarks (I have a VX50 with 8x Opteron 880 in the other room...):
Mark Hahn schrieb:
http://www.cybernex.co.uk/tyan_vx50_quad_opteron_servers.htm
afaikt, this is a ladder design:
c-c-c-c
| | | |
c-c-c-c
Not quite, this would make no use of two HT channels. Its like this:
c--c--c--c
| | \/|
| | /\|
c--c--c--c
(The two leftmost CPUs need their third HT to connect the two chipsets.)
who says it's so great? the HT fabric is pretty far from a "perfect"
low-latency 16-port crossbar, for instance. also, is it really cheaper?
how about if you compare to four 2-socket DC nodes?
Well, from my experiences with the first sold VX50 systems: If you have
a well scaling MPI application you are probably better off in
price/performance with a bunch of Opteron 180, 252 or 280 based machines
and Infiniband. (Or Intel Bensley...) I consider these VX50 beasts
more interesting for pre/postprocessing and not too large shmem/omp
applications. Such a machine is the answer to "16 threads - do I really
need an Altix?"
Best wishes,
Karsten
--
HPC System Engineer
Tel.: +49 3722 528 43
Fax: +49 3722 528 15
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MEGWARE Computer GmbH
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