This week, the New York Times ran a series of articles about data center power use (and abuse) “Power, Pollution and the Internet” (http://nyti.ms/Ojd9BV) and “Data Barns in a Farm Town, Gobbling Power and Flexing Muscle” (http://nyti.ms/RQDb0a). Among the claims made in the articles were that data centers were “only using 6 to 12 % of the energy powering their servers to deliver useful computation. Like a lot of media broadsides, the reality is more complex than the dramatic claims made in these articles. Technically they are correct in claiming that of the electricity going to a server, only a very small fraction is used to perform useful work, but this dramatic claim is not a fair representation of the overall efficiency picture. The Times analysis fails to take into consideration that not all of the power in the data center goes to servers, so the claim of 6% efficiency of the servers is not representative of the real operational efficiency of the complete data center.
On the other hand, while I think the Times chooses drama over even-keeled reporting, the actual picture for even a well-run data center is not as good as its proponents would claim. Consider:
A new data center with a PUE of 1.2 (very efficient), with 83% of the power going to IT workloads.
Then assume that 60% of the remaining power goes to servers (storage and network get the rest), for a net of almost 50% of the power going into servers. If the servers are running at an average utilization of 10%, then only 10% of 50%, or 5% of the power is actually going to real IT processing. Of course, the real "IT number" is the server + plus storage + network, so depending on how you account for them, the IT usage could be as high as 38% (.83*.4 + .05).
In a recent discussion with a group of infrastructure architects, power architecture, especially UPS engineering, was on the table as a topic. There was general agreement that UPS systems are a necessary evil, cumbersome and expensive beasts to put into a DC, and a lot of speculation on alternatives. There was general consensus that the goal was to develop a solution that would be more granular install and deploy and thus allow easier and ad-hoc decisions about which resources to protect, and agreement that battery technologies and current UPS architectures were not optimal for this kind of solution.
So what if someone were to suddenly expand battery technology R&D investment by a factor of maybe 100x of R&D and into battery technology, expand high-capacity battery production by a giant factor, and drive prices down precipitously? That’s a tall order for today’s UPS industry, but it’s happening now courtesy of the auto industry and the anticipated wave of plug-in hybrid cars. While batteries for cars and batteries for computers certainly have their differences in terms of depth and frequency of charge/discharge cycles, packaging, lifespan, etc, there is little doubt that investments in dense and powerful automotive batteries and power management technology will bleed through into the data center. Throw in recent developments in high-charge capacitors (referred to in the media as “super capacitors”), which add the impedance match between the requirements for spike demands and a chemical battery’s dislike of sudden state changes, and you have all the foundational ingredients for major transformation in the way we think about supplying backup power to our data center components.