Ah; this is a slightly different error than what Gilles was guessing from your prior description. This is what you're running in to: https://github.com/open-mpi/ompi/blob/v4.0.x/orte/mca/regx/fwd/regx_fwd.c#L130-L134
Try running with: mpirun --mca regex naive ... Specifically: the "fwd" regex component is selected by default, but it has certain expectations about the format of hostnames. Try using the "naive" regex component, instead. -- Jeff Squyres jsquy...@cisco.com ________________________________________ From: Patrick Begou <patrick.be...@univ-grenoble-alpes.fr> Sent: Thursday, June 16, 2022 9:48 AM To: Jeff Squyres (jsquyres); Open MPI Users Subject: Re: [OMPI users] OpenMPI and names of the nodes in a cluster Hi Gilles and Jeff, @Gilles I will have a look at these files, thanks. @Jeff this is the error message (screen dump attached) and of course the nodes names do not agree with the standard. Patrick [cid:part1.KfzAgK4Q.PG6VadQJ@univ-grenoble-alpes.fr] Le 16/06/2022 à 14:30, Jeff Squyres (jsquyres) a écrit : What exactly is the error that is occurring? -- Jeff Squyres jsquy...@cisco.com<mailto:jsquy...@cisco.com> ________________________________________ From: users <users-boun...@lists.open-mpi.org><mailto:users-boun...@lists.open-mpi.org> on behalf of Patrick Begou via users <users@lists.open-mpi.org><mailto:users@lists.open-mpi.org> Sent: Thursday, June 16, 2022 3:21 AM To: Open MPI Users Cc: Patrick Begou Subject: [OMPI users] OpenMPI and names of the nodes in a cluster Hi all, we are facing a serious problem with OpenMPI (4.0.2) that we have deployed on a cluster. We do not manage this large cluster and the names of the nodes do not agree with Internet standards for protocols: they contain a "_" (underscore) character. So OpenMPI complains about this and do not run. I've tried to use IP instead of host names in the host file without any success. Is there a known workaround for this as requesting the administrators to change the nodes names on this large cluster may be difficult. Thanks Patrick
