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Common Issues & FAQ

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Common problems with running MPI processes Link to this post

A common problem often encountered when running MPI processes is that the .mpd.conf file does not have the correct permission set. This file should be located in your home directory and is setup by the user to contain the MPD_SECRETWORD. This file is interrogated by MPI processes for this MPD_SECRETWORD and if the file can't be accessed the MPI processes will fall over. The correct setting for the permissions of this file can be set using the following command in a terminal window - chmod 600 ~/.mpd.conf

Re: Common problems with running MPI processes Link to this post

Another common issue is using the wrong MPI implementation.

Claritas is built with MPICH2, and will require MPICH2 to run correctly. There are several other MPI2 implementations around, including OpenMPI, LAM-MPI, MVAPICH2, etc. While these will provide MPI commands like "mpicc" and "mpif90", they won't work correctly with Claritas, because Claritas compiles and links code at runtime and therefore needs to use the same libraries.

Ubuntu has the correct MPICH2 packages in it's default repository, while RHEL/CentOS requires you to build from source or find a different repository that has MPICH2 packages available.

If you have two different implementations installed on your system (eg: MPICH2 and OpenMPI), you have to ensure you're using the correct one for Claritas. Typing "which mpif90" will tell you the path to the mpif90 wrapper, and should help you debug any problems. "mpich2version" is a command that will tell you the version of mpich2 you're running and how it was built.

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