Since its founding in 1974, NERSC has provided systems and services that maximize the scientific productivity of its user community. NERSC takes pride in its reputation for the expertise of its employees and the high quality of services delivered to its users. To maintain its effectiveness, NERSC proactively addresses new challenges. We observe three trends that NERSC needs to address over the next several years:

• the widening gap between application performance and peak performance of high-end computing systems
• the recent emergence of large, multidisciplinary computational science teams in the DOE research community
• the flood of scientific data from both simulations and experiments, and the convergence of computational simulation with experimental data collection and analysis in complex workflows.

NERSC’s responses to these trends are the three components of the science-driven strategy that NERSC will implement and realize in the next five years; science-driven systems, science-driven services, ng>science-driven analytics (Fig. 1). This balanced set of objectives will be critical for the future of the enterprise and its ability to serve the DOE scientific community.

• Science-Driven Systems: Balanced introduction of the best new technology for complete computational systems — computing, storage, networking, visualization and analysis.
• Science-Driven Services: The entire range of support activities, from high-quality operations and user services to direct scientific support, that enable a broad range of scientists to effectively use NERSC systems in their research. NERSC will concentrate on resources needed to realize the promise of the new, highly scalable architectures for scientific discovery in multidisciplinary computational science projects.
• Science-Driven Analytics: The architectural and systems enhancements and services required to integrate NERSC’s powerful computational and storage resources to provide scientists with new tools to effectively manipulate, visualize, and analyze enormous data sets derived from both simulation and experiment.

Science-Driven Systems
Applications scientists have been frustrated by a trend of stagnating application performance relative to dramatic increases in claimed peak performance of high performance computing systems. This trend has been widely attributed to the use of commodity components whose architectural designs are unbalanced and inefficient for large-scale scientific computations. It was assumed that the ever-increasing gap between theoretical peak and sustained performance was unavoidable. However, results from the Earth Simulator in Japan clearly demonstrate that a close collaboration with a vendor to develop a science-driven solution can produce a system that achieves a significant fraction of peak performance for critical scientific applications.

Realizing that effective large-scale system performance cannot be achieved without a sustained focus on application-specific systems development, NERSC has begun a science-driven systems strategy. The goal of this effort is to influence the vendors’ product roadmaps to improve system balance and to add key features that address the requirements of demanding capability applications at NERSC — ultimately leading to a sustained Pflop/s system for scientific discovery. This strategy involves extensive interactions between domain scientists, mathematicians, computer experts, as well as leading members of the vendors’ research and product development teams.

NERSC must be prepared for disruptive changes in processor, interconnect, and software technologies. Obtaining high application performance will require the active involvement of NERSC in understanding, driving, and adopting these technologies. The move towards open-source software will require additional efforts in software integration at NERSC.

The goal of the science-driven systems strategy is to enable new scientific discoveries, and that requires a high level of sustained system performance on scientific applications. The NERSC approach takes into account both credibility and risk in evaluating systems and will strike a balance between innovation and performance on the one hand and reliability on the other. While the discussion often focuses on the high-end platforms, NERSC will continue to emphasize maintaining Center balance, that is, improving all the systems at NERSC — storage, networking, visualization and analysis — commensurately with improvements in the high-performance computing platforms.