Enhancing I/O throughput via efficient routing and placement for large-scale parallel file systems

As storage systems get larger to meet the demands of petascale systems, careful planning must be applied to avoid congestion points and extract the maximum performance. In addition, the large data sets generated by such systems makes it desirable for all compute resources to have common access to this data without needing to copy it to each machine. This paper describes a method of placing I/O close to the storage nodes to minimize contention on Cray´s SeaStar2+ network, and extends it to a routed Lustre configuration to gain the same benefits when running against a center-wide file system. Our experiments using half of the resources of Spider - the center-wide file system at the Oak Ridge Leadership Computing Facility - show that I/O write bandwidth can be improved by up to 45% (from 71.9 to 104 GB/s) for a direct-attached configuration and by 137% (47.6 GB/s to 115 GB/s) for a routed configuration. We demonstrated up to 20.7% reduction in run-time for production scientific applications. With the full Spider system, we demonstrated over 240 GB/s of aggregate bandwidth using our techniques.