On Evaluating Decentralized Parallel I/O Scheduling Strategies for Parallel File Systems

This paper evaluates the impact of the parallel I/O scheduling strategy on the performance of the file access in a parallel file system for clusters of commodity computers (Clusterfile). We argue that the parallel I/O scheduling strategy should be seen as a complement to other file access optimizations like striping over several I/O servers, non-contiguous I/O and collective I/O. Our study is based on three simple decentralized parallel I/O heuristics implemented inside Clusterfile. The measurements in a real environment show that the performance of parallel file access may vary with as much as 86% for writing and 804% for reading with the employed heuristic and with the schedule block granularity.