Apple powers college supercomputer

By Ian Hardy
BBC ClickOnline

Everyone would love a supercomputer but with a price tag of around $100m each they are not easy to come by.

More than 1,000 G5s have been linked up

But in the United States staff and students at Virginia Tech have built one of the world's most powerful supercomputers for just $5m by plugging together hundreds of the latest computers from Apple.

The project involved placing 1,100 brand new Apple G5 towers side by side, making it the world's most powerful "homebuilt" system.

It is capable of 17.6 trillion floating point operations per second, with a combined storage capacity of 176 terabytes.

"Each individual G5 is a dual processor, 2GHZ machine with 4GB of memory. So it's extremely fast," said Pat Arvin, Project Coordinator at Virginia Tech.

The network is linked using 2,900 cables and runs at about 100 times faster than an average corporate network.

But the hard part of making a supercomputer is stability.

The project's chief architect, Srinidhi Varadarajan, had to write a special program called Deja Vu to ensure that if an individual computer crashed in the middle of a calculation lasting weeks, if not months, another computer would take over seamlessly.

"This is pretty much like open heart surgery because you're working on a computer and moving an application while it still continues to run," said Dr Varadarajan

"You cannot stop the program, actually, and that's the speciality of this system."

Heat and water

The supercomputer, unofficially nicknamed Big Mac, was built in just three months.

Chilled water is piped into the facility

Right from the start there were major hurdles that could only be overcome with significant construction in and around the building.

Running 1,100 computers in a 3,000-square-foot (280-sq-metres) area sends the air temperature well over 100 degrees Fahrenheit (38 Celsius).

The heat is so intense that ordinary air conditioning units would have resulted in 60-mph (95 km/h) winds. Specialised heat exchange cooling units were built that pipe chilled water into the facility.

"There are two chillers for this project," explained Kevin Shinpaugh, Director of Cluster Computing.

"They're rated 125 tonnes each in cooling capacity, and they pump 750 gallons per minute each. The water is at about 45 degrees Fahrenheit."

The power supply was another huge challenge. The supercomputer uses the same amount of electricity as 3,000 average sized homes.

Big science

In early September, the G5s started arriving by the lorry load and technicians rushed to install the hundreds of computers.

Technicians had to quickly install the machines

"We did 238 machines in little under two hours, so we were humming along as an assembly line," said Jason Lockhart, director of high performance computing.

A speedy installation was essential because Virginia Tech had to comply with an October deadline set by the National Science Foundation.

Missing that deadline would have meant automatic disqualification from the NSF's global supercomputer rankings, thereby denying the college any chance of competing for top scientific research projects worth hundreds of millions of dollars per year.

"A system of this size generally sees its best application in what is known as big science research; massive simulations, models, computational engineering systems," said Dr Varadarajan.

"Examples of these include things like nanoscale electronics; if you're trying to invent computer chips 30 years from now you're looking at atomic levels with a single atom acting as a switch."

Arguably Virginia Tech has revolutionised the world of supercomputing with a simplistic setup that can be duplicated around the globe by other institutions.

It has documented how it did this from start to finish so if others want to follow suit, they can send off for a kit that tells them how to do it.