version 1.8 offers new features that can make creating and accessing files with many datasets much faster. To use it one has to set the H5Pset_libver_bounds(fapl_id, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) properly to the file access property list used to create the dataset (version of HDF5 >= 1.8.5 also offer a H5F_LIBVER_18).
This is a one line change that can be very beneficial. Unfortunately versions of hdf5 < 1.8.0 (ie 1.6) cannot read these files. Currently I think QueenBee is the last production machine that uses this old version of HDF5. Since it will be retired soon apparently, I would like to suggest that we switch to the newer HDF5 vesion at that time.