Re: Cost Justifications

[DrFranken <midrange@xxxxxxxxxxxx>]

OK I wrote a certification question on the ratio between input power and 
output heat and got booed off the stage. SO I will simply tell you the 
answer. For each KW of input power (1000 Watts) you will get 3413 BTU of 
heat output. Now since a teeny tiny little bit of that 1000 watts went 
into creating LED light (a VERY teeny bit) and some into noise generated 
by the fans you might get a measly 3410 BTU of heat.  Point is that it's 
a straight line relationship between input power and output heat.  It's 
fairly common for HVAC guys who know there stuff to ask what the total 
power input to the data center is, what the percentage load on the UPS 
is, and use that number as a basis for calculating cooling requirements. 
If you put 100KVA IN you will need to get 341,300 BTU out somehow.

Now how much electricity it takes to remove those BTUs can vary A LOT. 
In very cold climates, outdoor air can be drawn through filters to cool 
the place (devices called 'economizers') and that's cheap. In hot 
climates very large amounts of A/C are used to cool such rooms and that 
cost can rival the power of the systems being cooled.  In the FrankenLab 
from about October through March 100% of the heat generated is turned 
into domestic hot water and then heat for the house.  In the summer it 
ends up in the swimming pool or down a dry well. Very economical indeed.

    - Larry 'DrFranken' Bolhuis

On 3/8/2011 6:09 PM, Evan Harris wrote:
> What's the heat differential ? And the power requirement for the
> cooling equipment to handle it ? :)
>
> As you've pointed out the OP should also consider the maintenance and
> license costs if any of keeping an existing machine versus upgrading
> as this is often a simpler sell to management as it's a direct cost.
>
> On Wed, Mar 9, 2011 at 9:45 AM, DrFranken<midrange@xxxxxxxxxxxx>  wrote:
> > Well the 720 and the 250 are about a wash in 'spec power' at 750 amd 782
> > watts respectively. That said, what you GET for those watts is a little
> > different. The biggest 250 was 75 (Seventy five!) CPW (20 interactive)
> > while the teeeeeeniest 720 is nearly 6,000 CPW (one core) and as much as
> > 46,300 with all eight cores going.  So a one core 720 is equal to Eighty
> > 250s in CPU capability.  IN practice I would expect the 720 to draw far
> > less than that and I measured a 2-core system with 6 drives closer to
> > 100 Watts with IBM i 7.1 simply idling. (No user work at the time.)
> >
> > The 720 also comes with a 3 year warranty so you drop maintenance cost.
> >
> > I also did a comparison of a POWER5 550 to a POWER7 750 and the ratio
> > there is 100 to 1 on power per CPW. That is the 750 generates 100 times
> > more CPW per input Watt than a 550! That's a lot of savings!
> >
> >      - Larry