ROMIO is a high-performance, portable implementation of MPI-IO, the I/O chapter in MPI-2 and has become a de-facto standard for MPI-I/O (in terms of interface and semantics). ROMIO is a library parallel to the MPI library for the application, but depend on an MPI to set up the environment and do communication. See chapter 3.2.6 for more information on how to compile and link applications with MPI-IO needs.