Technology changes pretty fast.
IBM Roadrunner, which was the world’s fastest supercomputer as recently as June 2009, and the first supercomputer to hit 1 petaflop, is now obsolete and has been shut down. At a cost of $120 million and with a lifetime of just five years, you might accuse the Department of Energy of wastefulness — but shutting down Roadrunner is actually a thrifty, cost-saving measure.
Roadrunner was built at Los Alamos National Laboratory (LANL) with the primary goal of modeling the decay of the US nuclear weapons stockpile, under the auspices of the National Nuclear Security Administration’s Advanced Simulation and Computing (ASC) program. The supercomputer actually dates back to 2002, when it was conceived as a three-phase design that would eventually reach 1.7 petaflops. The first phase, which was a standard AMD Opteron 2210 (dual-core) cluster, went online in 2006 and reached just 71 teraflops. The second phase, which introduced some older Cell processors (as in the PlayStation 3) in a hybrid design, went online in 2007. Finally, phase three saw 6,912 Opterons and 12,960 PowerXCell processors married together, breaking the 1-petaflop barrier in summer 2008. The PowerXCell is essentially a souped-up version of the PS3′s CPU.
All told, IBM Roadrunner had 130,464 processor cores and 103.6 terabytes of RAM across 296 server cabinets, with a top performance of 1.456 petaflops in November 2008. Beyond its position at the pinnacle of the Top500 list of supercomputers, Roadrunner was notable for being the first hybrid supercomputer, essentially using Opterons to handle all of the basic I/O, with the Cells acting as accelerators. This was a contentious design decision at the time, though it obviously paid off: 62 of the world’s top 500 computers are hybrids (accelerator/coprocessor) design, with Titan (currently the world’s fastest) also being a hybrid. Today, though, Nvidia’s Tesla and Intel’s Xeon Phi are the accelerator of choice — not Cell. (See: What do scientists actually do with supercomputers?)
Today, IBM Roadrunner is still the twenty-second-fastest supercomputer in the world. Why, then, is it being shut down? Put simply: Power consumption. As of November 2012, Roadrunner required 2,345 kilowatts to hit 1.042 petaflops (444 megaflops per watt). The computer directly above it, the Oakleaf-FX in Tokyo, requires just 1,117 kilowatts to reach 1.043 petaflops — less than half the power for the same performance. It gets worse as you go up the list, towards some of the latest and greatest supercomputers: Titan, at Oak Ridge National Laboratory, produces 17.6 petaflops and consumes just 8,209 kilowatts — 2,143 megaflops per watt, or almost five times the efficiency of Roadrunner.....MORE