Collective I/O on Contiguous Datasets

Because contiguous datasets have all their data elements stored in a single block within the HDF5 file, the main task for performing collective I/O operations is to create an MPI datatype that corresponds to an HDF5 dataspace selection.  Then, the MPI datatypes describing the elements selected in the file and in the application’s memory buffer are passed down to the MPI-IO VFD where the read or write callback is invoked.


There are four types of HDF5 dataspace selections:


Each type of selection generates a different MPI datatype:

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