(click image for larger view)

Google's data center

Not long ago, Google data centers were a closely guarded secret. The company's technical innovations were regarded as a competitive advantage.

Google opened its kimono before more than 100 industry leaders and journalists at its Mountain View, Calif., headquarters and now has posted a video tour of one of its data centers and videos of its presentation on YouTube.

"We disclosed for the first time details about the design of our ultraefficient data centers," Google engineer Jimmy Clidaras said in a blog post Thursday. "We also provided a first-ever video tour of a Google container data center as well as a water treatment facility. We detailed how we measure data center efficiency and discussed how we reduced our facility energy use by up to 85%. The engineers who developed our efficient battery backup solution even brought an actual Google server to the event."

At the Google Data Center Efficiency Summit, Google said that its Power Usage Efficiency (PUE) -- the ratio of total data center power to power used by facility IT equipment -- had improved from an average of 1.21 in the third quarter of 2008 to 1.16 during the fourth quarter of 2008.

A PUE of 1.0 represents a data center with no power loss to cooling or energy distribution. The typical corporate data center, based on 2006 statistics, has a PUE of 2.0 or more.

At 1.16, Google's PUE exceeds the EPA's most optimistic target for data center efficiency in 2011, which is a PUE of 1.2.

Google showed off a data center that it has been operating since 2005. With a 10-megawatt equipment load, it contains 45 shipping containers, each of which holds 1,160 servers. It operates at a PUE of 1.25.

Power efficiency increasingly affects revenue for businesses that depend on data centers. In a presentation at the Google event, James Hamilton, VP and distinguished engineer at Amazon Web Services, explained that while servers look like the major cost of data centers, computing costs are trending downward while power and power distribution costs are flat or trending upward. "Power and things functionally related to power will be the most important thing, probably next year," he said.

One of the more surprising innovations of Google's server design -- seen here in a CNET photograph -- appears to be rather mundane: The company's custom-designed server hardware includes a 12-volt battery that functions as an uninterruptible power supply. This obviates the need for a central data center UPS, which turns out to be less reliable than on-board batteries.

"This design provides Google with UPS efficiency of 99.9%, compared to a top end of 92% to 95% for the most efficient facilities using a central UPS," explains Rich Miller in a post on Data Center Knowledge.

InformationWeek has published an in-depth report on data center unification. Download the report here (registration required).