Characterization of I/O Requirements in A Massively Parallel Shelf Sea Model

It is now recognized that a high level of I/O performance is crucial in making effective use of parallel machines for many scientific application codes. This paper considers the I/O requirements in one particular scientific application area: three-dimensional modeling of continental shelf sea regions. The authors identify some of the scientific aims that drive the model development, and the consequent impact on the I/O needs. As a case study, the authors take a parallel production code running a simulation of the North Sea on a Cray T3D platform and investigate the I/O performance in dealing with the dominant I/O component: dumping of results data to disk. To place the performance issues in a more general framework, the authors construct a simple theoretical model of I/O requirements, and use this to probe the impact of available I/O performance on current and proposed scientific objectives.