Oak Ridge National Laboratory
PetaScale computing platforms need to be coupled with efficient IO subsystems that can deliver commensurate IO throughput to scientific applications. In order to gain insights into the deliverable IO efficiency on the Cray XT platform at ORNL, this paper presents an in-depth efficiency evaluation of its parallel IO software stack. The authors' evaluation covers the performance of a variety of parallel IO interfaces, including POSIX IO, MPI-IO, and HDF5. Moreover, they describe several tuning parameters for these interfaces and present their effectiveness in enhancing the IO efficiency.