How Many Servers Does Google Have?

Back in April, I wrote about Facebook’s Open Compute Project, an attempt to apply open-source principles to the design of data centers, a considerable change from the traditional secrecy about data center operations by companies like Google.  Some of the traditional reticence is undoubtedly due to security concerns, and some of it may be due to the counter-intuitive observation that running data centers is actually a core part of these firms’ strategy.

Google has never said how many of its custom-designed servers it uses to deliver its array of services (such as search, Google Mail, Google Documents, YouTube, and so on); some guesses put the figure at over 1 million.   According to a report at Data Center Knowledge, however, this estimate is probably a bit high, with the true number being closer to 900,000.  Google still isn’t talking, at least not directly, but the lower estimate is derived from some recent data on electricity consumption.

Google never says how many servers are running in its data centers. The new estimate is based on information the company shared with Stanford professor Jonathan Koomey, who has just released an updated report on data center energy usage.

Koomey says that his numbers are educated guesses, based on Google’s comments on its overall electricity consumption.   He believes that Google’s infrastructure efficiency, comparable to that of other large cloud providers, as well as the energy-efficient design of Google’s servers, means that the company uses about 220 megawatts of power, about  1% of total global electricity use by data centers.

The New York Times also has an article on Koomey’s report [PDF], which covers the growth of data center power use from 2005 through 2010.   Some forecasts had predicted that electricity consumption would grow by 100% or more over the period (which it did from 2000 to 2005); however, the combined effects of the global recession and more efficient technologies resulted in an increase of “only” 56%. worldwide.

Mr. Koomey found that electricity used by data centers worldwide grew significantly, but it was an increase of only about 56 percent from 2005 to 2010. In the United States, power consumption increased by 36 percent, according to Mr. Koomey’s report, titled “Growth in Data Center Power Use 2005 to 2010.”

Koomey wasn’t able to disentangle the effects of the economy and of technology, bur did indicate that the most important factor in the lower growth rate was a smaller than expected increase in the number of physical servers, possibly due in part to increased use of virtualization.  The lower growth occurred despite continued emphasis on increasing capacity.

The slowdown in the rate of growth of electricity use is particularly significant because it comes in the midst of the biggest build-out of new data center capacity in the history of the industry

The relative importance of data centers as power consumers is higher in the US than worldwide, as one might expect.

Electricity used in global data centers in 2010 likely accounted for between 1.1% and 1.5% of total electricity use, respectively. For the US that number was between 1.7 and 2.2%.

None of this should be taken to mean that the electricity consumption of data centers is likely to level off any time soon.  The Data Center Knowledge report suggests that Google is setting up new data centers provisioned with 50 megawatts or more of power; if the company’s current total usage is ~220 megawatts, this suggests that it is planning for some significant capacity expansions.