Running a twofold multidir sim on 4 mpi ranks - something like: mpirun -np 4 /usr/lib64/openmpi/bin/mdrun_openmpi_d -s topol.tpr -c confout.gro -o traj.trr -x traj.xtc -multidir sim1 sim2 -nsteps 500 -v fails with *** An error occurred in MPI_Barrier while mpirun -np 2 /usr/lib64/openmpi/bin/mdrun_openmpi_d -s topol.tpr -c confout.gro -o traj.trr -x traj.xtc -multidir sim1 sim2 -nsteps 500 -v works! (Note: Using same tpr files for all sims for testing) Additionally, it prints the following confusing message: No option -multi I believe all of this worked before the -multi option was removed. *(from redmine: issue id 2403, created on 2018-02-06 by junghans, closed on 2018-02-16)* * Relations: * relates #2425 * duplicates #2414 * Changesets: * Revision fa3593ec6b33ee61eaa51938891dadc6435a0534 by Berk Hess on 2018-02-16T13:51:12Z: ``` Correct multisim MPI barrier An MPI barrier used with multisim was called on incorrect ranks and a barrier was missing. Fixes #2403 Change-Id: I06a66167afc8dca9cdd4ca9b4f9a806984a6ec7a ``` * Revision 6358ce7313d40e682e1324cf38ba9974ab082df4 by Berk Hess on 2018-03-01T08:44:09Z: ``` Fix mdrun multisim with separate PME ranks When running multiple simulations using separate PME ranks, mdrun would call MPI_Barrier with MPI_COMM_NULL on some ranks. Note: no new release note needed, since this fixes a fix. Refs #2403 Fixes #2431 Fixes #2432 Change-Id: I7fe96a15b5030dea3e093d12850f89f00ccc9f48 ```