[AusNOG] Data Suburb

Mark Newton newton at atdot.dotat.org
Thu Jan 5 11:36:26 EST 2012

On Thu, Jan 05, 2012 at 10:15:43AM +1000, Luke Smith wrote:

 > Unless its *very* modular and you can totally turn off the bits you are not
 > using then you simply can't expect a half used facility to have the same
 > efficiency as a fully utilised one half the size.

Some of the bits you'd need to turn off include aircon for the 
onsite staff, desktop PCs for the NOC, office lighting, losses from
UPSs running at the worst end of their load-vs-efficiency curve,
and the blowers/fans/pumps that keep air circulating even when the
rest of your cooling plant happens to be idle.

An empty datacentre's PUE is a divide-by-zero error :-) Fixed overheads
dominate until you've reached at least a modicum of scale.

If PUE was the only important target to aim for, we'd all be building
datacentres at Mawson Base and running them with the windows open.
But practically speaking, every datacentre project is a balance of
compromises between capex, opex, cashflow and operational flexibility.
Will some of those compromises have short-term impact on PUE?
Sure. So take solace in the fact that the ramp-up phase is probably only
about 5% of the facility's useful operating life, and concentrate
your optimization efforts on the remaining 95% to get the best long-
term payoff.

  - mark

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