[kwlug-disc] [OT] linux server power

Paul Nijjar paul_nijjar at yahoo.ca
Fri Jan 28 21:40:43 EST 2011

On Thu, Jan 27, 2011 at 08:08:34PM -0500, Insurance Squared Inc. wrote:
> A quick back of the napkin estimate from the electrician indicated the  
> two machines might be costing me 30+ bucks a month in hydro alone.

That seems quite high. 

> Step one is I think to replace both machines with something newer and  
> more efficient (hopefully without losing speed).

Have you measured the usage as part of the electrician's visit? There
are electricity measuring meters available to borrow at the Kitchener
Public Library. I don't know whether the Region of Waterloo libraries
have something similar.  (We also have a meter, but we're far away
from you and I would have to see whether we can loan it out.) 

I have found this exercise really educational in measuring my personal
electricity use. For example, my desktop computer/monitor/scanner was
drawing 15W of electricity just by being plugged in. Since this
machine stays dormant for long periods, I now explicitly unplug the
power bar after use. That's a different scenario, but there could be
appliances (TVs, etc) in your house that could benefit from such an

You may well find that your 750W power supplies are drawing nowhere
near 750W to power your servers. 

> Are there any tricks/suggestions for lowering power costs on hardware,  
> and on linux servers specifically? i.e. my voip server needs to be live  
> 8 to 8, but outside that could probably be dormant except if triggered  
> by an incoming call.  A wake on incoming phone call might help.

CPUs come with power saving technologies (Intel SpeedStep; AMD
Cool'N'Quiet) that can save some power when enabled. 

One crazy idea might be to use laptops instead of full-blown servers
for your server needs. This comes with disadvantages, but laptops tend
to be pretty good at power management -- and they come in with
built-in UPSes. 

Another idea is probably not what you are looking for: use lightweight
low-power devices where possible. For space reasons we bought an ALIX
kit for one of our pfSense firewalls, and I have been pretty happy
with it: 


It was pricy for the computing power you get, but it worked well for
our needs. 

I think it draws between 5-10W of power (but I don't quite remember).
On the other hand it is only running as a firewall. The big
disadvantage is that this would be a step down (maybe a big step down)
from the servers you are running now. 

- Paul


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