Dynamic I/O characterization of I/O intensive scientific applications

Abstract

Understanding the characteristic I/O behavior of scientific applications is an integral part of the research and development efforts for the improvement of high performance I/O systems. This study focuses on application level I/O behavior with respect to both static and dynamic characteristics. We observed the San Diego Supercomputer Center's Cray C90 workload and isolated the most I/O intensive applications. The combination of a low-level description of physical resource usage and the high-level functional composition of applications and scientific disciplines for this set reveals the major sources of I/O demand in the workload. We selected two applications from the I/O intensive set and performed a detailed analysis of their dynamic I/O behavior. These applications exhibited a high degree of regularity in their I/O activity over time and their characteristic I/O behaviors can be precisely described by one and two, respectively, recurring sequences of data accesses and computation periods. Key Words: empirical I/O behavior, supercomputer applications