Hi, I am considering the following change to the PHDF5. Since you folks are major users of PHDF5, I would like to see how this may affect you. ===================================================== The parallel tests sometimes get bitten by mpirun that does not "forward" environment variables to all MPI processes.. E.g., if one tries mkdir /pfs/acheng/test$$ setenv HDF5_PARAPREFIX "/pfs/acheng/test$$/" mpirun -np 3 ... Not all implementations of mpirun will/can forward the $HDF5_PARAPREFIX to all mpi processes. The result is that different mpi process may have a different value of what $HDF5_PARAPREFIX is and that often result in hard to trace errors. I want to create a collective function getenv_all(MPI_COMM comm, int root, char *name) where process root will make the getenv(envname) and then broadcasts the result to all comm processes. Then in the PHDF library and test programs, all getenv() that is used by all processes will be replaced by getenv_all(). This provides an implementation independent of mpirun's ability to forward environment variables but it also takes away the ability that an MPI application may want to use different values for the same environment variable name in different processes. E.g., in some processes, the PFS is mounted at /scratch but others may be under the pathname of /net/scratch. This is pretty rare since such an environment really gives the MPI users quite a headache. My questions are two fold: 1) has anyone ever needed to setup the value of an environment variable with different values for different MPI processes? 2) Anyone sees any other problem of adopting setenv_all()? Below is a list of environment variables used by HDF5 library, test programs and tools. HDF5_PREFIX Serial test files prefix. Used by serial tests. HDF5_PARAPREFIX Parallel test files prefix. Used by Parallel tests. HDF5_NOCLEANUP No cleanup after tests. Used by both serial and parallel tests. USER Used by serial and parallel tests. LOGIN Used by serial and parallel tests. srcdir Tells where the HDF5 Source directory is. Used by serial test programs to support --srcdir configure option. HDF5_DRIVER Which Virtual File Driver to use. Used by serial tests. HDF5_MPI_INFO Setup MPI-IO INFO object. Used by parallel tests. HDF5_DEBUG Turn on more library debug tracing. Used by the library. HDF5_DISABLE_VERSION_CHECK Override library version checking. Used by the library. H5FD_mpio_Debug Turn on specific parallel MPIO file driver debug tracing. Used by PHDF5 library. HDF5_MPI_OPT_TYPES Use MPI type optimization. Used by PHDF5 Library. COLUMNS Used by h5ls. -- Albert Cheng Scientific Data Technologies Group, NCSA 217-244-1955 voice University of Illinois at Urbana-Champaign 217-244-1987 fax