Unable to run openMPI from two machines

[sacharin1993]

Unable to run openMPI from two machines

[ggouaillardet]

/etc/hosts is not a valid Open MPI hostfile.

[sacharin1993]

Thanks for the reply but I am not sure I understand what you mean I should change.
In the past using a etc.hosts file as the ones I attached in the former message I managed to have openMPI run correctly with two nodes.
Even if I did not mention it, I have also tried -this time - using a "machines" text file to read nodes from A and B (just these names or IP and the names). If I just write A and have openMPI run with 64 cores $ mpirun --hostfile machines -np 64 ./hello , it works. If I change the name to B or A and B (and changing -np to 128 ) and launch mpirun from A , it does not work. Justs hungs as with the other situation (/etc/hosts)

[ggouaillardet]

make sure there is no firewall between both hosts (passwordless ssh is necessary but not enough). With Open MPI v4, try restricting to known interfaces, for example mpirun --mca btl_tcp_if_include eth0 --mca oob_tcp_if_include eth0 ...

[jsquyres]

@sacharin1993 Please see https://docs.open-mpi.org/en/v5.0.x/getting-help.html#for-problems-launching-mpi-or-openshmem-applications

[github-actions]

It looks like this issue is expecting a response, but hasn't gotten one yet. If there are no responses in the next 2 weeks, we'll assume that the issue has been abandoned and will close it.