The HDF5 groups is apparently contemplating adding a new high-level API for "HPC HDF5", based on parallel HDF5. I find the idea intriguing, as it would move much code that we have currently written in Carpet (and that we will have to write to address the "slow recovery" issue) into HDF5. In particular, recovering would consist essentially of a single call to H5HPCdataset_read_mult_all(), which would read multiple datasets from multiple processes.
-erik