Energy consumption vs % utilization?
nanog-list at nrg4u.com
Wed Oct 27 09:13:37 UTC 2004
Steven M. Bellovin wrote:
> In message <Pine.WNT.4.61.0410261429110.3340 at vanadium.hq.nac.net>, Alex Rubenst
> ein writes:
>>I've done quite a bit of studyin power usage and such in datacenters over
>>the last year or so.
>>>I'm looking for information on energy consumption vs percent utilization. In
>>>other words if your datacenter consumes 720 MWh per month, yet on average
>>>your servers are 98% underutilized, you are wasting a lot of energy (a hot
>>>topic these days). Does anyone here have any real data on this?
>>I've never done a study on power used vs. CPU utilization, but my guess is
>>that the heat generated from a PC remains fairly constant -- in the grand
>>scheme of things -- no matter what your utilization is.
> I doubt that very much, or we wouldn't have variable speed fans. I've
> monitored CPU temperature when doing compilations; it goes up
> significantly. That suggests that the CPU is drawing more power at
> such times.
From running a Colo in a place with ridiculus high electricity engery
costs (Zurich/Switzerland) I can tell you that the energy consuption
of routers/telco (70%) and servers (30%) changes changes significantly
throughout the day. It pretty much follows the traffic graph. There
is a solid base load just because the stuff is powered up and from there
it goes up as much as 20-30% depending on the routing/computing load of
the boxes. To simplify things you can say that per packet you have that
many "mWh" (milli-Watt-hours) per packet switched/routed or http requests
answered over the base load. I haven't tried to calulate how much energy
routing a packet on a Cisco 12k or Juniper M40 cost though. Would be
very interesting if someone (student) could do that calculation.
More information about the NANOG