Patrick,
In recent Open MPI releases, the default component for MPI-IO is ompio (and no more romio)
unless the file is on a Lustre filesystem. You can force romio with mpirun --mca io ^ompio ... Cheers, Gilles On 12/3/2020 4:20 PM, Patrick Bégou via users wrote:
Hi, I'm using an old (but required by the codes) version of hdf5 (1.8.12) in parallel mode in 2 fortran applications. It relies on MPI/IO. The storage is NFS mounted on the nodes of a small cluster. With OpenMPI 1.7 it runs fine but using modern OpenMPI 3.1 or 4.0.5 the I/Os are 10x to 100x slower. Are there fundamentals changes in MPI/IO for these new releases of OpenMPI and a solution to get back to the IO performances with this parallel HDF5 release ? Thanks for your advices Patrick
