In “Facilities for the Future of Science: A Twenty Year Outlook,” the Office of Science has identified the need for creating new and/or improving on the current computational capability as a critical aspect of realizing its advanced scientific computing research vision.2 It identified the NERSC upgrade as a near-term priority to ensure that NERSC, DOE’s premier scientific computing facility for unclassified mission-critical research, continues to provide high-performance computing resources to support the requirements of scientific discovery.
As a high-end facility that serves all the DOE-SC programs with capability and high-end capacity resources, NERSC is a key resource in DOE-SC’s portfolio of computing facilities. NERSC has established a reputation for providing reliable and robust services along with unmatched support to its users. Because of investments such as SciDAC, and the important role that computation will play in Genomics:GTL (formerly Genomes to Life) and the Nanoscale Science Research Centers, demands for computational resources in DOE-SC will continue to grow at a rapid rate, and NERSC’s growth must keep pace. NERSC supports a large number (200–300) of projects of medium to large scale, occasionally requiring a very high capability resource, that fall within the mission of the Office of Science. The scientific productivity enabled by NERSC is demonstrated by the 2,206 papers in refereed publications in 2003 and 2004 that were based at least in part on work done at NERSC.
In NERSC’s experience, there is a continuum of scientific computing systems and facilities. There are a few research groups with experienced users and very high computational requirements who are in a good competitive position to use a Leadership Class Facility. There is a much larger number of PIs and projects with high-end requirements who are best served by NERSC’s high-end systems and comprehensive services, both of which distinguish NERSC from leadership computing and midrange computing centers, such as institutional or departmental clusters. Capability users include both single principal-investigator teams and community science teams. NERSC’s science-driven services are important for both types of high-end users.
NERSC supports large-scale teams working on advanced modeling and simulation “community codes” whose development is shared by entire scientific research communities. These codes employ new mathematical models and computational methods designed to better represent the complexity of physical process and to take full advantage of current computational systems. NERSC provides focused support for these teams.
NERSC also supports single-PI teams consisting of a lead researcher and his or her group of collaborators, postdocs, and students, usually concentrated at a single location. For this class of users, NERSC’s science-driven service is important because they are usually less knowledgeable about computational technologies and they lack the resources to establish in-depth collaborations with computer science or mathematics experts. Computing at NERSC not only produces important scientific insights but also gives these users and teams the opportunity to advance to the leadership computing level for their most challenging computations.
As a centralized facility properly staffed and managed, NERSC provides the best possible mechanism for technology transfer between the computational efforts of different research programs. Moreover, a concentration of computing resources provides a more flexible mechanism to address changing priorities. SC’s priorities for its programs sometimes change quickly because it is a mission agency. A general-purpose facility like NERSC, with a staff prepared to support the broadest possible array of scientific disciplines, allows DOE to switch priorities and quickly apply its most powerful computing resources to new challenges.
NERSC’s role as a general scientific computing facility requires it to provide resources that are of common utility to the programs of the Office of Science. However, NERSC must be responsive to the specific needs of each program. Specific support for different programs, tailored to their varying needs, has been a key to the success of the center. Examples range from the collaborative effort of NERSC staff in scaling INCITE applications to 2,048 and 4,096 processors, to the operation of the PDSF cluster for the high energy and nuclear physics communities. The breadth of NERSC’s support is best expressed by Figures 2 and 3, which summarize NERSC usage by discipline and institution.
