Facebook prooudly announced today that its fourth data center is now serving traffic. Located in Altoona, Iowa, the new data center joins those found in Prineville, Forest City, and Lulea to bring Facebook to you every day.

Like the other data centers, Altoona is cooled by 100% outside air, and it features the latest in hyper-efficient Open Compute Project gear.

Altoona is also our first data center to take advantage of facebook's new networking fabric, which will help the company scale much more efficiently as more and more people connect on Facebook around the world.

Data-center networks are based on clusters, each of which may have hundreds of racks of servers linked together through a massive switch with high-speed uplinks to handle the traffic. However, the "machine-to-machine" traffic - data moving among servers and even clusters - is growing many times faster than the bits actually going out to the Internet. To cope with the tremendous traffic, in place of those big clusters Facebook added much smaller groups of servers (pods) made up of just 48 racks. So what was left to do was to use switches with 48 ports to link the racks in the pod and 48 more to connect with other switches that communicate with the rest of the pods. With the new architecture, Facebook can supply 40-Gigabit Ethernet pipes from any rack in the data center to any other.The identical pods and standard fabric switches allow for easy expansion of both computing and network capacity, Facebook says. This measn that Facebook can continue to add pods as long as physical space and power allow.

In addition to sharing the core concepts of the network fabric, Facebook says it may later share designs and code with other companies.

Altoona will also be powered by 100% renewable energy, thanks to the new wind project Facebook worked with MidAmerican Energy to develop in nearby Wellsburg, Iowa. Wellsburg adds 140 MW of new renewable energy to the grid in Iowa.