Across the top of this figure are five boxes, labeled P00 through P04, representing five processors. Below that are three boxes stacked vertically, labeled from top to bottom as:

There are double-sided arrows between each of the five processor boxes and the topmost of these three boxes, representing data flow in both directions. Across the bottom of the figure is a box labeled "Parallel File System". There are five double-sided arrows between this box and the box above it labeled "MPI-I/O", again representing data flow in both directions.