[Beowulf] Re: bonic projects on a cluster

David Mathog mathog at caltech.edu
Fri Mar 21 16:26:48 PDT 2008

Robert G. Brown wrote:
> On Fri, 21 Mar 2008, David Mathog wrote:

> > I have a nit to pick with them.  

> > My point being, with respect to the original poster, letting something
> > like boinc run on a cluster for outside use could easily end up costing
> > the cluster's owner many thousands of dollars a year.
> I typically estimate $1/watt/year because in generaly you have to pay to
> remove those watts once you release them into the wild of a server room.

Right.  The original analysis was for PCs which might be at home, where
an open window would suffice.  $1/watt/year is certainly easier to
calculate and more accurate for a room with A/C.

> In the case of cluster users, one rarely turns off the nodes so the
> issue is much more idle consumption vs non-idle consumption, a marginal
> cost on the order of the $20-30 or so differential between his case 2
> and his case 3, at my slightly higher power cost estimate because
> cluster nodes would definitely require cooling.

Under pressure from the big computing farm users, and to some extent,
the government, computers are getting better at dropping to lower power
usage when idle.  In this (and virtually nothing else) the Via C7
is the best game in town, since its idle power consumption is a tiny 0.1
watts, vs. 20 watts peak.  The move to multiple cores has not helped in
this cause though, since as far as I know none of them can fully power
down N-1 cores and those N-1 cores' support circuitry, resulting in N
idling cores instead of just 1.

> at  this point the question is moot because you'd have to be crazy to
buy a
> CRT >>over<< a flatpanel when you have to replace a monitor

Right,  assuming you could even find one.  The trickiest thing about the
LCDs is that it can be hard to distinguish between blanked and idle.
With a kill-a-watt it is clear, but not many people have those. The
other way is to wait a while and see if it cools off, but some of them
run so cool in the first place that that is a difficult test.

> So while I agree that the docs are misleading, that doesn't mean that a
> real cost-benefit analysis will show that it is always a bad idea to
> share resources.

I didn't mean to imply that it was.  


David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech

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