Got that right
A lot of our racks in the DC aren't even half full. The DC will only sell you so much power per rack*, and with the density of 1U servers you can stick in a rack, blowing your power budget is super easy.
The reason they will only sell you so much isn't because they are 'green' however, it's mainly to stay within their cooling window. Fully loaded racks mean more heat now than they did when the DC was designed.
* OK, thats not strictly true, but the cost for power goes up exponentially. I think we get 15A per rack, in some racks we've gone to 18A, which increases the price by almost half as much again. Going to 21A/24A, which is what we would need to run a full rack requires you to sell your first born.
Nice article Trev