NERSCPowering Scientific Discovery Since 1974

Parallel I/O in Practice

Sunday, Nov. 11

Robert Latham - Argonne National Laboratory

Robert Ross - Argonne National Laboratory

Brent Welch - Panasas

Katie Antypas - NERSC / Lawrence Berkeley National Laboratory



I/O on HPC systems is a black art. This tutorial sheds light on the state-of-the-art in parallel I/O and provides the knowledge necessary for attendees to best leverage I/O resources available to them. We cover the entire I/O software stack from parallel file systems at the lowest layer, to intermediate layers (such as MPI-IO), and finally high-level I/O libraries (such as HDF-5). We emphasize ways to use these interfaces that result in high performance, and benchmarks on real systems are used throughout to show real-world results. This tutorial first discusses parallel file systems in detail (PFSs). We cover general concepts and examine four examples: GPFS, Lustre, PanFS, and PVFS. We examine the upper layers of the I/O stack, covering POSIX I/O, MPI-IO, Parallel netCDF, and HDF5. We discuss interface features, show code examples, and describe how application calls translate into PFS operations. Finally we discuss I/O best practice.