Phil Carns from Argonne gave this talk at the 2017 Argonne Training Program on Extreme-Scale Computing. “Darshan is a scalable HPC I/O characterization tool. It captures an accurate but concise picture of application I/O behavior with minimum overhead. Darshan was originally developed on the IBM Blue Gene series of computers deployed at the Argonne Leadership Computing Facility, but it is portable across a wide variety of platforms include the Cray XE6, Cray XC30, and Linux clusters.  Darshan routinely instruments jobs using up to 786,432 compute cores on the Mira system at ALCF.”