You must build netCDF-4 properly to take advantage of parallel features.
HDF5 must be built with --enable-parallel.
Typically the CC environment variable is set to mpicc, and the FC
to mpifc (or some local variant.) You must build HDF5 and netCDF-4
with the same compiler and compiler options.
The netCDF configure script will detect the parallel capability of
HDF5 and build the netCDF-4 parallel I/O features automatically. No
configure options to the netcdf configure are required.
For non-parallel build the configure modifies the netcdf.h file to
define types MPI_Comm and MPI_Info as ints.
Parallel I/O is tested in nc_test4/tst_parallel.c,
nc_test4/tst_parallel2.c, and nc_test4/tst_parallel3.c, if the
--enable-parallel-tests option to configure is used.
Currently the Fortran 77 and Fortran 90 parallel I/O are not being
automatically tested.