Re: rack power question

[Joe Greco <jgreco () ns sol net>]

> On Sat, 22 Mar 2008, Patrick Giagnocavo wrote:
> > Would someone pay extra for > 7KW in a rack?  What would be the maximum you 
> > could ever see yourself needing in order to power all 42U ?
>
> As you recognize, its not an engineering question; its an economic 
> question.  Notice how Google's space/power philosphy changed between
> leveraging other people's space/power, and now that they own their own 
> space/power.
>
> Existing equipment could exceed 20kW in a rack, and some folks are
> planning for equipment exceeding 30kW in a rack.
>
> But things get more interesting when you look at the total economics
> of a data center.  8kW/rack is the new "average," but that includes
> a lot of assumptions.  If someone else is paying, I want it and more.
> If I'm paying for it, I discover I can get by with less.

That may not be the correct way to look at it.

There's a very reasonable argument to be made that the artificial economic
models used by colocation providers has created this monster to begin with.

The primary motivation for many customers to put more stuff in a single
rack is that the cost for a rack subsidizes at least a portion of the power
and cooling costs.  A single rack with two 20A circuits typically costs less
than two racks with a 20A circuit each.  To some extent, this makes sense.
However, it often costs *much* less for the single rack with two 20A
circuits.

Charging substantially less for rack space, even offset by higher costs for
power, would encourage a lot of colo customers to "spread the load" around
and not feel as obligated to maximize the use of space.  That would in turn
reduce the tendency for there to be excessive numbers of hot spots.

The economic question of how to build your pricing model ultimately becomes
an engineering question, because it becomes progressively more difficult to
provide power and cooling as density increases.

Or, to quote you, in an entirely different context:

> If I'm paying for it, I discover I can get by with less.

The problem is that this is currently true for values of "it" where "it"
equals "racks."

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
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