Thanks to everyone for great responses.

-----Original Message-----
From: Edward Ned Harvey [mailto:[email protected]] 
Sent: Tuesday, November 23, 2010 10:06 PM
To: Dustin Puryear; [email protected]; [email protected]; LOPSA Tech List
Subject: RE: Moving a few servers from colo back to office

> From: [email protected] [mailto:[email protected]]
> On Behalf Of Dustin Puryear
> 
> 2 Dell 1850 - dual power supply - 1U
> 1 Dell 1950 - dual power supply - 1U
> 1 Dell NAS  - dual power supply - 2U

Buy a kill-a-watt.
Measure the power consumption of each of those things.  This is easy to do
since they all have dual power supplies.  You just plug a power-strip into
the kill-a-watt, and then move the power cords of the servers to it, one at
a time so nothing gets interrupted.

Measure both the VA and W.  Idle or average.
Then, do something to stress out the machines.  Zip up a large directory (or
a few simultanesouly to stress multiple cores) or just download a machine
stressing program if you trust them.  Measure the max VA and max W.

You will notice:  The measured average and max power consumption will be
nowhere near what any manual or calculator allows for.  Typically I find all
the manuals etc overestimate by around 4x.  Which translates into real
dollars wasted in excess cooling capacity and UPS capacity.

With measurements of power consumption, your UPS spec becomes trivial.  But
what to do about cooling capacity?  
1 kwh = 3412 BTU.  


> The new office is being designed as we speak, so we have some say in terms
> of ductwork and airflow in the server closet. However, we don't have much

The ductwork is generally insufficient and irrelevant ... because your
servers are on 24/7, and the building HVAC is probably shut off for weekends
etc.




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