[Beowulf] Re: Beowulf Digest, Vol 25, Issue 9
edkarns at firewirestuff.com
Sat Mar 4 09:57:33 PST 2006
On Mar 3, 2006, at 12:53 PM, beowulf-request at beowulf.org wrote:
> O.K. So Option 3 -- 32 desktops from HP or Dell-- is eliminated
> because I cannot afford to upgrade the air conditioning unit in the
> available and I cannot afford an onsite service contract to cover
> repair costs.
Trade offs: air conditioning or service contract or both? Without a
good cool air source (colder than ambient temp), the service contract
becomes almost mandatory. If you can engineer great ventilation with
lots of cooler air entering the farm, you might be able to skate on
both air conditioning and service contracts. Change the room air 2 to
4 times per hour or keep ambient room air from exceeding 90 F. with
reasonable good circulation around the systems. Sometimes a good,
easily opened sky light with a good sized exhaust fan will solve a
world of circulation problems. Paying attention to the original heat
load generation will save huge amounts of expense.
Often overlooked: extra large CPU power supplies run cooler. If
standard power supplies run warm to the touch (100 F. +), upgrading
to 50 % larger will reduce heat loads (300 watt upgraded to 450 watt
supply). A CPU that only needs 200 watts will only consume that 200
watts, no matter the size of the supply ... and a 300 watt supply
"stressed" to 60% of rated load will run warm, but a 450 watt supply
running at 45% of rated duty will not produce nearly as much heat ...
and the larger will last longer. (Alternative below)
Sometimes overlooked: larger, older monitors run warmer than small
ones or cheap flat screen LCD monitors. (Big monitors are needed only
to sell the next round of grant refinancing. :>)
Not to be ignored: Larger gauge power wires are cooler. This may seem
like micromanagement, but 32 systems feed by 32 sets of #16 gauge
plug strips and power lines will also generate some heat. Spending
10% more for fewer #12 gauge power feeds might save enough to be
important. Healthier power / surge strips, larger circuit breakers =
> In response to RGB's request for more information: Here are my
> budgetary constraints and my needs
> Budget ~US $25K, with the possibility of $5K ... My
> simulations ... require in excess of 512 MB of memory ... ideally
> twice that amount. ... should go for gigabit ethernet.
Yes ... 32 CPUs w/ 512K RAM plus several flat screen monitors.
Assuming ISA style "mini tower" boxes, 2 to 3 GigaHertz each, would
have a total heat load requirement of around 6000 watts (running) ...
could be offset by two window mounted air conditioners ... US$400 to
$500 x 32 = US$12K to US$16K+, plus accessories and power lines and
air conditioning and installation and service, etc., etc. ... quite
possibly a budget buster.
A possible alternative: Last week Apple announced the newer version
of the Mac Mini ... meaning that the previous models could shortly
be picked up quite reasonably ... and picking up a number of these
[1.25 or 1.4 GigaHertz, 512K RAM (upgradable), ethernet and FireWire
equipped, 50 watt (observed, running)] systems ... is certainly food
for thought ... as the FireWire ports as fast or faster than
1000baseT ethernet and work with Apple's own "beowulf
scenario" (http://www.apple.com/xserve/workgroupcluster/) or if
preferred a Linux variant ( yellowdoglinux.com /
And the heat load of 32 of these could be resolved with a window fan
and a maintenance contract could be resolved by getting some
spares ... :>)
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