Los Alamos National Laboratory

Four years ago, Roadrunner was the world's fastest supercomputer. But it has lost a step on today's speed leaders and will be shut down today in preparation for dismantling.

Created in 2008 to monitor the U.S. nuclear weapons stockpile, the IBM supercomputer was the first system to break the petaflop barrier, hitting 1.026 petaflops shortly after its installation at the Los Alamos National Laboratory. (1 petaflop is equal to a quadrillion, or one thousand trillion, calculations per second.) It would ultimately sit atop of the Top500 supercomputers list three times.

In its five years of operation, the Roadrunner was the "workhorse" behind the National Nuclear Security Administration's Advanced Simulation and Computing program, providing key computer simulations for the Stockpile Stewardship Program.

"Roadrunner exemplified stockpile stewardship: an excellent team integrating complex codes with advanced computing architectures to ensure a safe, secure and effective deterrent," Chris Deeney, NNSA assistant deputy administrator for Stockpile Stewardship, said in a statement. "Roadrunner and its successes have positioned us well to weather the technology changes on the HPC horizon as we implement stockpile modernization without recourse to underground testing."

Based on the IBM QS22 blades and x86 chips from Advanced Micro Devices, the $121 million Roadrunner was the world's first hybrid supercomputer. In total, Roadrunner took up 278 refrigerator-size server racks, connecting 6,562 dual-core AMD Opteron and 12,240 Cell chips -- advanced versions of the same processor that powers Sony's PlayStation 3.

"Roadrunner was a truly pioneering idea," Gary Grider, of the Laboratory's High Performance Computing Division, said in a statement. "Roadrunner got everyone thinking in new ways about how to build and use a supercomputer. Specialized processors are being included in new ways on new systems, and being used in novel ways. Our demonstration with Roadrunner caused everyone to pay attention."

While Roadrunner is still one of the world's 30 fastest supercomputers, advances in chip design have left it behind. The Oak Ridge National Laboratory's Titan supercomputer is currently the speed leader, clocking in at 17.59 petaflops per second. Built by Cray, the system is composed of 18,688 nodes, with each containing a 16-core AMD Opteron processor and an Nvidia Tesla GPU.

In addition to Roadrunner's weapons-monitoring duties, it also helped map the HIV genetic tree and simulated the Big Bang in an attempt to better understand dark matter, calculating the physics behind 64 billion proto-galaxies, each about the size of a billion of our suns.

Before Roadrunner is dismantled, researchers will have about a month to perform experiments on the operating system's memory compression techniques to aid design of future supercomputers.

"Even in death, we are trying to learn from Roadrunner," Grider said. "These are things we never could try while Roadrunner was running production problems."