Thom Dunning, director of the National Center for Supercomputing Applications

10/15/2012  8:00 am

The Blue Waters supercomputer facility at the National Center for Supercomputing Applications on the University of Illinois campus celebrates Petascale Day on Oct. 15. Petascale refers to computing and data in the quadrillions. In an interview with News Bureau physical sciences editor Liz Ahlberg, NCSA director Thom Dunning talks about computing and data at the supercomputer scale and how the Blue Waters facility is advancing research at the U. of I.

What is a supercomputer?

A supercomputer is the most powerful computer available at any given time. Today, Japan has the most powerful supercomputer in operation – the Kei computer, which is located in Kobe. Blue Waters is comparable to the Kei computer and is the most powerful computer on a university campus. These two computing giants will enable breakthroughs in many areas of science and engineering.

Of course, as computing technology advances, the supercomputers of today become the desktop computers of tomorrow. This is literally true: The desktop computers available today are as powerful as the most powerful supercomputers in the early 1990s. As computing technology advances, computers even more powerful than Blue Waters will be deployed. However, over its five-year lifetime, Blue Waters will enable a wealth of scientific breakthroughs.

What does it mean when we say that Blue Waters is a petascale facility?

Computer technologists define the speed of a computer by the number of arithmetic operations that it can perform. A typical arithmetic operation is the addition or multiplication of two 14-digit numbers. If a computer can perform 1,000 arithmetic operations in a second, we refer to this as a kiloscale computer. A petascale computer can perform a quadrillion (1015, one thousand million million) operations in a second. This is a fantastic amount of work: It would take nearly a million desktop computers to do the same amount of work. To put it another way, if you could multiply two 14-digit numbers together on your calculator every second, it would take you 32 million years to do the same amount of work that Blue Waters can do each and every second.

What kinds of things does a supercomputer do that other computers can’t?

The mathematical equations that describe the world that we live in are exceedingly difficult to solve. To be able to solve these equations on even the most powerful supercomputers, we must make approximations. As computers become more and more powerful, we are able to make fewer and fewer approximations. This means that our computational models more accurately describe what is observed in the real world. Models that accurately describe the world are important in advancing our knowledge of the world around us, helping industry design and produce better products, and aiding policymakers make decisions.

Another advantage of very powerful computers is that we can model more complex systems on the computer. An example of a complex system is a tornado or a hurricane. The formation, strength and path of tornadoes and hurricanes depends on many factors – temperature, pressure, humidity, wind speed and direction, and so on – all of which must be included in the computational model to properly describe the phenomena.

What kind of research goes on at NCSA?

NCSA’s mission is to provide scientists and engineers with the computing resources and technical support that they need to advance their research. The breadth of research being conducted on NCSA’s computers is staggering. It ranges from studies of the elementary particles that make up atoms and molecules that form our everyday world to weather and climate to the birth and evolution of our universe.

The results of these simulations are critical to understanding observations from the Large Hadron Collider, the design of new materials and the processes of life, preparing for natural disasters, and interpreting what will be seen in the proposed Large Synoptic Survey Telescope. Computational modeling and simulation have become so pervasive that nearly all areas of science and engineering are being transformed by it.

At the University of Illinois, faculty will be using Blue Waters to model the behavior of the polio virus, model the birth of tornadoes, better understand the factors that control climate change, and gain a better understanding of how to use these giant computers. In addition to these Illinois-led projects, other Illinois faculty members are key investigators in other projects that will be using Blue Waters.

What happens to all the data from Blue Waters?

Blue Waters has one of the largest data storage systems in the world. It can store more than 25 petabytes of data on high-speed disks and more than 300 petabytes of data on slower-speed tapes. A typical desktop computer can store 1 terabyte on its hard disk. This means that Blue Waters can store 25,000 times more data on disk and 300,000 times more data on tape. This presents some unique challenges because scientists have not traditionally been able to generate this much data in a single simulation. Fortunately, Blue Waters has special processors in it, called graphics processing units, which allow scientists to visualize the results of their simulations on the same computer that generated the data – often in real time.

Blue Waters is connected to the outside world by very large data pipes. At the beginning, Blue Waters will connect to Chicago and the national networks at more than 100 gigabits per second (Gbps), or 7,000 times faster than a high-speed connection to a home. The connection speed can be upgraded to 400 Gbps as needed by the scientists using Blue Waters. However, even at this speed, much of the data must stay on disks and tapes in the National Petascale Computing Facility – the data sets are much too large to transfer over the national networks even if we transported them to Chicago.

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