[Beowulf] Re: newbie's dilemma (Mark Hahn)

[Ed Karns]

On Mar 3, 2006, at 12:00 PM, beowulf-request at beowulf.org wrote:

>
>> Note also that I'm guessing that these boxes draw somewhere  
>> between 200
>> and 300 watts fully loaded with tasks (anybody out there measure?
>
> I recently did some measurements on new nodes: HP DL145G2's with  
> 8GB ram,
> 2x80G disks, quadrics elan4 cards:
>
> 		2x DC opt/2.2	2x SC opt/2.6
> booting         259-317		244-313
> idle            265		255
> 1p thrash -g6	286		275
> 1p stream	291		284
> 2p		290-301		310
> 4p		290-338
>
> "idle" means nothing explicitly running (though the distro includes a
> surprising number of irrelevant daemons.)  "thrash -g 6" is a  
> program that
> allocates 6GB and just repeatedly memset's it.  it's single-threaded,
> but since 6GB is large enough to require both CPU's banks of  
> memory, the
> other cpu is not inactive.  1/2/3 are an openmp version of stream, run
> with "numactl -l".


Trying to micromanage these power loads can be counter productive and  
time wasting. Better: just take your worst case estimate of power  
usage, double it or even quadruple it ... and that is what you should  
plan to "wire into the walls".

Example: four slave processors at 300 watts each plus a master  
server / control workstation at 450 watts (worst case) ... And  
associated monitors, printer(s), accessories =
CPUs
300 x 4 = 1200 watts
+                450 watts
------------------
Monitors
100 x 5 =  500 watts
accessories
  100 x 5 = 500 watts
-----------------

... looks like about 3000 watts to me ... so wire four power runs of  
2000 watts each from your subpanel (#12 AWG with ground on four 20  
amp breakers) to the computer room (works up to 150 feet). Use quad  
utility boxes on the remote ends and add filtered surge protectors to  
suit ...

Ed Karns
FireWireStuff.com


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