How dynamic is the Grid? Towards a quality metric for Grid information systems

Grid information systems play a core role in today´s production Grid Infrastructures. They provide a coherent view of the Grid services in the infrastructure while addressing the performance, robustness and scalability issues that occur in dynamic, large-scale, distributed systems. Quality metrics for Grid information systems are required in order to compare different implementations and to evaluate suggested improvements. This paper proposes the adoption of a quality metric, first used in the domain of Web search, to measure the quality of Grid information systems with respect to their information content. The application of this metric requires an understanding of the dynamic nature of Grid information. An empirical study based on information from the EGEE Grid infrastructure is carried out to estimate the frequency of change for different types of Grid information. Using this data, the proposed metric is assessed with regards to its applicability to measuring the quality of Grid information systems.