Sorry for the delay - this one slipped past me.

There was an internal change to the way we handle hostfiles in Open MPI, so the parameter changed. The correct way to specify a system-wide default host file is indeed to set OMPI_MCA_orte_default_hostfile in your environment, or to set orte_default_hostfile in the default MCA parameter file. You can also specify it on the command line as --default-hostfile.

The value is NULL by default as we do not have a default name for the system-wide hostfile. So you have to specify it for us.

Given that our handling of hostfiles has changed, it might be worth reviewing the notes on the wiki:

Alternatively, there is a man page in 1.3 that also covers this material: man orte_hosts


Begin forwarded message:

From: Daniel Felix Ferber <>
Date: July 16, 2008 10:09:01 AM EDT
Subject: [OMPI users] Getting default hostfile on Open MPI 1.3
Reply-To: Open MPI Users <>


On Open MPI 1.2, I used following command to get the default host file:
ompi_info -a --parseable | grep rds_hostfile_path

Now, on Open MPI 1.3, the parameter does not seem to exist anymore. I checked that there is another parameter (mca:orte:base:param:orte_default_hostfile), but its value is always empty.

Which file whould I used for a system-wide default host file? Is there another way to query the path for this default host file? Or is a command to query which hosts are going to be used by mpi by default?

Best regards,
Daniel Felix Ferber
users mailing list

Jeff Squyres
Cisco Systems