[AusNOG] Power audit

[Damien Gardner Jnr]

I guess it depends on your environment..

Sure, CPU-idle to CPU-maxxed, you'll see some difference if you have big 
power-hungry CPU's (30-40W difference per CPU on a 90W CPU?).  It's 
enough that back in the isa.net.au days we stopped running seti at home 
overnight, as it added up across 90 servers!

But how often do you max out your CPU's in a production environment?  
Our XenServer farm never sees more than about 15% cpu use on average.   
Power usage on our DL360 G5's is 192W idle, 226W with all 8 cores in 
use. The Thecus N8800Pros sitting behind them run 60W idle, 92W during a 
full raid verify.

So sure, if everything was maxxed out, we'd see ~300W more power usage 
than at idle.  But that's only 15% difference, so not too bad :)

--DG


On 6/06/2013 8:39 AM, Pinkerton, Eric wrote:
> Forgive my naivety, but I have always assumed that power consumption changed depending upon the load the server is under?  - If this is the case then isn't there a problem with a single measurement at one point in time?
>
>
> -----Original Message-----
> From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Damien Gardner Jnr
> Sent: Wednesday, 5 June 2013 7:13 PM
> To: Ross Wheeler
> Cc: ausnog at ausnog.net
> Subject: Re: [AusNOG] Power audit
>
> Yeah, that's how I do it..  30cm long IEC-IEC cable with a section of outer removed, clamp meter around the active, unplug one side supply, plug cable inline with it, and plug back into server.  Take reading, remove from line and plug original cable directly back in.  Repeat for
> second PSU.   Repeat for every server.
>
> Last time I ran it was just after we'd moved into one particular suite, where we were being told the gear in our new rack was pulling 4kW.  Was news to me, as while running the whole lot up in the lab, it'd been on a single 3kVA UPS, at about 2/3 load.. Sure enough, after measuring everything manually, it measured out at 1.9KW.  Sent a please explain to the provider, never heard back, notice their portal is still showing close to 4KW for our rack, but haven't had a 'you are using way too much' email from them again..  Guess it's good money, overcharging all their clients by 100% for power usage, they'd rather just sweep it under the carpet..? ;)
>
> --DG
>
> On 5/06/2013 3:31 PM, Ross Wheeler wrote:
>>
>>> On that basis, I'm tossing overboard as much kit as I can jettison
>>> and looking for like-minded sub-let tenant prospects who need a few
>>> RU for switches and could use our interconnects to a number of
>>> carriers. They will get a PDU as recommended but I'm sticking with my
>>> monthly manual email request for usage reporting until I muster the
>>> courage for downtime.
>> One thing I didn't see mentioned - how much of your kit has dual
>> supplies?
>> Simple matter to unplug just one power source and connect to
>> power-monitoring device, then once that supply is back online, do the
>> other lead?
>>
>> Just a thought...
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>
> --
> Damien Gardner Jnr
> VK2TDG/VK2DGJ. Dip EE. GradIEAust
> rendrag at rendrag.net -  http://www.rendrag.net/
> --
> We rode on the winds of the rising storm,
>    We ran to the sounds of thunder.
> We danced among the lightning bolts,
>    and tore the world asunder
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