Roadrunner was a supercomputer built by IBM for the Los Alamos National Laboratory in New Mexico, USA.

[4] It was also the fourth-most energy-efficient supercomputer in the world on the Supermicro Green500 list, with an operational rate of 444.94 megaflops per watt of power used.

IBM built the computer for the U.S. Department of Energy's (DOE) National Nuclear Security Administration (NNSA).

The Roadrunner used Red Hat Enterprise Linux along with Fedora[11] as its operating systems, and was managed with xCAT distributed computing software.

[12] Roadrunner occupied approximately 296 server racks[13] which covered 560 square metres (6,000 sq ft)[14] and became operational in 2008.

Roadrunner differed from other contemporary supercomputers because it continued the hybrid approach[13] to supercomputer design introduced by Seymour Cray in 1964 with the Control Data Corporation CDC 6600 and continued with the order of magnitude faster CDC 7600 in 1969.

To realize the full potential of Roadrunner, all software had to be written specially for this hybrid architecture.

The hybrid design consisted of dual-core Opteron server processors manufactured by AMD using the standard AMD64 architecture.

[16] This machine was one of the earliest hybrid architecture systems originally based on ARM and then moved to the Cell processor.

The first phase of the Roadrunner was building a standard Opteron based cluster, while evaluating the feasibility to further construct and program the future hybrid version.

This Phase 1 Roadrunner reached 71 teraflops and was in full operation at Los Alamos National Laboratory in 2006.

It was built to full scale at IBM’s Poughkeepsie, New York facility,[1] where it broke the 1 petaflops barrier during its fourth attempt on May 25, 2008.

[18] Los Alamos will perform the majority of the supercomputer's destruction, citing the classified nature of its calculations.