U.S. to use climate to help cool exascale systems

Computerworld - In a picturesque spot overlooking San Francisco Bay, the U.S. Department of Energy's Berkeley Lab has begun building a new computing center that will one day house exascale systems.

The DOE doesn't know what an exascale system will look like. The types of chips, the storage, the networking and the programming methods that will go into these systems are all works in progress.

DOE is expected to deliver to Congress by the end of this week a report outlining a plan for reaching exascale computing by 2019 to 2020 and its expected cost.

But what the DOE does have an idea about is how to cool these systems.

The Computational Research and Theory (CRT) Facility at Berkeley will use outside air cooling. It can rely on the Bay area's cool temperatures to meet its needs about 95% of the time, said Katherine Yelick, associate lab director for computing sciences at the lab. If computer makers raise the temperature standards of systems, "we can use outside cooling all year round," she said.

The 140,000-square-foot building will be nestled in a hillside with an expansive and unobstructed view of the Bay. It will allow Berkeley Lab to combine offices that are split between two sites. It will also be large enough to house two supercomputers, including exascale-sized systems. "We think we can actually house two exaflop systems in it," said Yelick. The building will be completed in 2014.

Supercomputers use liquid cooling, but this building will also use evaporative cooling. Under this process, hot water goes up into a cooling tower where evaporation helps to cool it. The lowest level of the Berkeley building is a mechanical area that will be covered by a gradient that is used to pull in outside air, said Yelick.

An exascale system will be able to reach 1 quintillion (or 1 million trillion) floating point operations per second, which is roughly 1,000 times more powerful than a petaflop. The government has already told vendors that an exascale system won't be able to use more than 20 megawatts of power. To put that in perspective, a 20 petaflop system today is expected to use somewhere in the range of 7 megawatts. There are large commercial data centers, with multiple tenants, that are now being built to support 100 megawatts and more.