Warning: PetscViewerHDF5SetCollective(viewer,PETSC_TRUE) is ignored for HDF5 versions prior to 1.10.3 or if built without MPI support
PetscViewer Object: 1 MPI process
  type: hdf5
  Viewer format = HDF5_XDMF
  Filename: my.hdf5
  Vectors with blocksize 1 saved as 2D datasets: TRUE
  Enforce single precision storage: FALSE
  MPI-IO transfer mode: independent