[Beowulf] Estimating cluster power consumption

Robert G. Brown rgb at phy.duke.edu
Thu Dec 15 08:55:20 PST 2005

On Thu, 15 Dec 2005, Douglas Eadline wrote:

> Here is a data point:
> The Value Cluster (http://www.clustermonkey.net//content/view/41/33/) is
> eight Sempron 2500 processors. The head node has 512 MByte of RAM, 64MB
> AGP Video card, a DVD/CD Reader/Burner, 160 GBytes of RAID 1 storage, two
> FastE links, and one GigE link. The seven worker nodes have 256 MBytes of
> RAM, a FastE link, and a GigE link and no hard drive.
> Using a Kill-A-Watt I measured between 650-675 Watts running under load.
> A Kill-A-Watt device is a great investment when doing something like this
> so you don't end up building a Kill-A-Self cluster.
> And, BTW, I use Wake-on-Lan to power up the worker nodes when I need to
> use the cluster. That way I don't Kill-My-Wallet with eight nodes running
> 24x7.

Good point.  I forgot to mention in my little treatise on the subject
that electrical costs are typically $0.60 to $1.00 per watt per year, so
when you cost out that 16 node (1000+ watt) cluster don't forget to
budge the well over $600 a year it will cost to feed it AND COOL IT.
Remember, it will be like having a KW+ space heater in the room it lives
in.  Sure, Canada may get cold in the winter (so you can reuse the
heat), but in the summer you'll need to run the AC 24x7 if you run the
cluster 24x7 EVEN if it is cool to nice outside.

This is what limits my home cluster to no more than 10 nodes, not
electrical capacity.  I'm probably paying close to $50 or $60 per month
as it is.


> --
> Doug
>> Hi all. I'm trying to track down some threads from
>> this group that date back to the fall of 2003 (Sept -
>> Nov). These don't seem to be in the Beowulf mailing
>> list archive. In particular, I read in Jeff Layton's
>> "Cluster Environments" article
>> (http://www.clustermonkey.net//content/view/40/32/)
>> that some cluster power considerations were discussed
>> in these threads.
>> Alternatively, if someone here has some insights and
>> can spare a few moments, I have a few questions.
>> First I should say that I just have a little
>> experimental cluster (5 nodes including master) right
>> now, but have an opportunity to more than double this
>> size very cheaply. The compute nodes are a mixture of
>> 366 - 450 Mhz boxes, 128 - 256 Mb ram. Currently they
>> have hard drives, but I'm seriously considering going
>> diskless (for the learning experience, amoung other
>> things). Also, the compute nodes are just boxes (no
>> monitor, keyboard, or mouse). The master node has an
>> 1800 AMD cpu, 512 ram, and 60 Gb hard drive. I'll be
>> mainly using the cluster for number crunching
>> experiments (primality testing, various integer
>> factorisation implemetations, etc). A typical cluster
>> run could last anywhere from a day to several weeks
>> (possibly months?).
>> My house, which contains my cluster room, is rather
>> old. Looking at my breaker panel, it looks like my
>> cluster room shares a 15 amp breaker with an adjoining
>> room (sad, I know).
>> Questions
>> 1) About how many of the above mentioned nodes would I
>> be able to safely run?
>> 2) Is there any chance of a fire hazzard if the
>> breaker is overloaded or will the breaker just trip?
>> 3) How does one estimate how many nodes they can
>> safely run?
>> 4) Would running the cluster diskless help much with
>> power consumption? What about no CD and floppy drive?
>> 5) How much juice should be flowing to the room to run
>> a cluster of 16 such nodes?
>> 6) What's the least expensive way of getting more
>> electricity to the room? I can't do it myself (at
>> least I think I can't). Which is the more desirable --
>> increasing the existing breaker amperage (if possible)
>> or getting a second breaker box (or replacing the
>> existing box with a bigger and better box)? The house
>> has copper wiring in the basement, which may affect
>> the cost (I also live in Canada too, eh!).
>> 7) What are some good references to answer such
>> questions? I'd even spend money on a book, if it were
>> recommended highly enough.
>> Thanks in advance
>> Rob
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Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu

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