# Introduction¶

The DIRAC program suite is parallelized using the MPI2 protocol.

See related works involving parallelization implementation, [Pernpointner2003], [Saue1997], [Knecht2008], [Knecht2010a], [Fleig2006], [Fleig2001], [Fleig2003].

# Parallel run information¶

My shell environment variables are not forwarded to the compute nodes. What do I have to do?

Assuming you are using the pam script to submit your parallel calculation you can forward any environment variable, e.g., LD_LIBRARY_PATH, to the slave-node shell by adding to you pam command line:

./pam --mpiarg="-x LD_LIBRARY_PATH"    # for OpenMPI
./pam --mpiarg="-envall"               # for IntelMPI and MPICH(2)

In the latter case ALL environment variables will be forwarded in one shot whereas for OpenMPI you may need to provide the most essential environment variables individually. These may be for a typical parallel DIRAC run:

LD_LIBRARY_PATH
BASDIR
PATH