## Supercomputers

Overview

At LANL, there is a close coupling of information science with computational science, which seeks to deepen our understanding of a variety of complex systems through the integrated use of physical and mathematical models implemented on high performance computers, and applied mathematics, which focuses on practical problems and uses the formulation and study of mathematical models.

LANL has one of the largest supercomputing centers on the planet, with massive resources for both classified and unclassified scientific simulation, along with world-class computational physicists, computer scientists, and mathematicians. The result is a unique and tight integration of theory, modeling, and computational science.

# New Cielo Supercomputer Arrives at Los Alamos

Cray Inc. has delivered a new supercomputing platform to support all three NNSA national laboratories: Los Alamos, Sandia, and Lawrence Livermore. Named Cielo (Spanish for "sky"), this petascale (more than one quadrillion floating point operations per second) supercomputer will help NNSA ensure the safety, security, and effectiveness of the nuclear stockpile while maintaining the moratorium on testing.

The first phase of Cielo installation at Los Alamos is complete. The 2010 installation consists of 72 cabinets, 6,704 compute nodes, 107,264 compute cores, and 221.5 terabytes of memory. The total hardware will take up approximately 1,500 feet and use less than 4 megawatts of memory. The 2011 phase-two upgrade will expand the system to 96 cabinets with nearly 9,000 compute nodes, and approximately 300 terabytes of memory.

Cielo is the next-generation capability-class platform for the Advanced Simulation and Computing Program. Cielo will have more than 10 times the computing power of NNSA's current computing platform, the Purple supercomputer (about to be retired) at Lawrence Livermore. This additional increase in speed in Cielo will enable scientists to increase their understanding of complex physics, as well as improve confidence in the predictive capability for stockpile stewardship.

The supercomputer is housed at the Nicholas C. Metropolis Center for Modeling and Simulation, where both Los Alamos and Sandia will share day-to-day operations. In its primary role, Cielo will run the largest and most demanding workloads involving modeling and simulation. Cielo will be primarily utilized to perform milestone weapons calculations.

Keywords: theory supercomputers modeling mathematical models math digital libraries computational science cielo applied math