Running MPI jobs with WebCom

A "typical" MPI job consists of 4 components: an MPI binary; an optional machines file; a set of optional input files and a parameterised start script. Of these, the machines file and the starting script are most prone to change from run to run on the same parallel architecture or on a different architecture. Moving an MPI job to a different architecture will precipitate the greatest changes in these and possibly the other components. The work associated with making and managing these changes is tedious and error-prone, especially if the user-base is large, andlor the underlying system is dynamic in size or is heterogeneous. This problem can be addressed by employing an abstract machine to separate the MPI launch process from the underlying parallel architecture. In this role the WebCom abstract machine can readily be used to generate a parallel architecture from component machines, to dynamically create a machines file and startup script and, if necessary, to stage the binary and input files. Change management is also addressed by employing WebCom to manage user accounts, shared file space, data storage and on-going run-time costs.