Can MPI Be Used for Persistent Parallel Services?

MPI is routinely used for writing parallel applications, but it is not commonly used for writing long-running parallel services, such as parallel file systems or job schedulers. Nonetheless, MPI does have many features that are potentially useful for writing such software. Using the PVFS2 parallel file system as a motivating example, we studied the needs of software that provide persistent parallel services and evaluated whether MPI is a good match for those needs. We also ran experiments to determine the gaps between what the MPI Standard enables and what MPI implementations currently support. The results of our study indicate that MPI can enable persistent parallel systems to be developed with less effort and can provide high performance, but MPI implementations will need to provide better support for certain features. We also describe an area where additions to the MPI Standard would be useful.