Hi, I'd like to have a better understanding of how Hydra works and how MPI processes "discover" how to connect to one another. I'm guessing something roughly like this happens: - mpiexec launches and ssh connection to each node, and sets some environment variables that will indicate to the created processes how to connect to one another; - MPI processes are created, and when calling MPI_Init they read the right environment variables to build MPI_COMM_WORLD. Is this correct? If so, where could I find information about the environment variables at play? Thanks, Matthieu _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss