The widespread adoption of cluster computing as a h.igh performance computing platform has seen the growth of data intensive scientific, engineering and commercial applications such as digital libraries, climate modeling, computational chemistry, computational fluid dynamics and image repositories. However, I/O subsystem performance has not been keeping pace with processor and memory performance, and is fast bewming the dominant factor in overall system performance. Thus, parallel I/O has become a necessitg in the face of performance improvements in other areas of computing systems. Th,is paper addresses the problem of parallel I/O scheduling on cluster computing systems in the presence of data replication. We propose two new I/O scheduling algorithms and evaluate the relative performance of the proposed policies against two existing approaches. Simulation results show that the proposed policies perform substantially better than the baseline policies.