Hallo Mark,
Mittwoch, 13. Mai 2009, meintest Du:
>> I'm currently shopping around for a cluster-expansion and was shopping
>> for options. Anybody out here who's bought new hardware in the recent
>> past? Any suggestions? Any horror stories?
MH> I think the answer depends on time-frame. if you're bw-sensitive,
MH> you go nehalem for the time being.
I'm really surprised that everyone just screams "Nehalem" - of course the
platorm is the fastest that you can buy for money at the moment. It is the
youngest design so that is not suprising.
But clustering is always about price/performance. And AMD doesn't look so bad
there. Shanghai-pricing was lowered in February and another pricedrop is
expected when Istanbul is launched. So Nehalem is faster but more expensive.
For some Applications it is "more expensive" than it is "faster".
Memory, CPUs and Chipsets for Intel are expensive - what you can buy from AMD
is "old" hardware that is in the market now for quite some time. It is simply
cheaper.
The 2.4..2.6 GHz Shangais are interesting.
MH> for the near future, I'm interested to see how AMD's next-gen "istanbul"
works out.
It seems to be very interesting.
When Clovertown/Harpertown was launched by INtel it seemed like they designed
the CPU just for getting to the top500. High HPL-scores but other applications
did not always perform good. Istanbul seems to be the perfect top500-CPU. You
reach a high Number of cores in a small power footprint. HPL-efficiency is very
good. Let's see how real applications behave ... what i've seen so far was
looking interesting enough!
MH> AMD obviously needs
MH> to break out past ddr2/800 - it would be kind of surprising if they
They will ... but having a stable platform was also important. And AMD kept the
socket-F now for quite some time.
MH> went 6c/socket without some improvement. AMD has made a big deal
MH> about the cache snooping, but I'm not sure how much it matters for
MH> the main market (2-socket).
You have two things:
HyperTransport3 - some Shanghai have it (the really fast ones with the odd
product numbers). And of course all Istanbuls. It enables them to handle a lot
more coherency-trafic. But in a 2-way mainboard it is not a big performance
impact.
HT-Assist - some kinde of snoop filter for Istanbul. Without this
Istanbul probably wouldn't scale to 6cores at all. But real world performance
seem to be interesting... so HT-Assist seem to make a difference.
MH> if you're considering 4-socket, I'd
MH> certainly think about whether to wait for istanbul.
Istanbul or at least Shanghais with HyperTransport3 - it makes a much bigger
difference there...
>> We've been using Dell SC1435's with Quad-Core AMD 2354 Opterons @
>> 2.2GHz. 16 Gig RAM.
MH> 2G/core seems to be fairly safe. although it's overkill for a lot of
MH> users, ram is also pretty cheap - 6x 4G dimms for dual-i7 is probably
MH> pretty sensible.
12 x 2 for E-Series Xeons or 6 x 4 for X-Series Xeons.... but that is another
thing with Nehalem: you have to buy 50% more RAM (if you are just looking for
2GB/Core) to get good performance. Same is true for Istanbul... the metrics are
changeing ;-)
Jan
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