Oak Ridge National Laboratory
In this paper, the authors present an extensive characterization, tuning, and optimization of parallel I/O on the Cray XT supercomputer, named Jaguar, at Oak Ridge National Laboratory. They have characterized the performance and scalability for different levels of storage hierarchy including a single Lustre object storage target, a single S2A storage couplet, and the entire system. Their analysis covers both data- and metadata-intensive I/O patterns. In particular, for small, non-contiguous data intensive I/O on Jaguar, they have evaluated several parallel I/O techniques, such as data sieving and two-phase collective I/O, and shed light on their effectiveness.