There are two HDF formats, HDF4, and HDF5 which each have their own libraries and drivers. HDF4 is more common, but HDF5 is the next generation format.  

 * http://www.gdal.org/frmt_hdf4.html - hdf4 driver docs
 * http://www.gdal.org/frmt_hdf5.html - hdf5 driver docs

= Building with HDF4 = 

NCSA HDF library can be downloaded from the [http://hdf.ncsa.uiuc.edu/ The NCSA HDF Home Page] at the the [http://www.ncsa.uiuc.edu/ National Center for Supercomputing Applications].

If your OS distribution already contains prebuilt HDF library you can use one from the distribution.

Please note, that NCSA HDF library compiled with several defaults which is defined in ''hlimits.h'' file. For example, ''hlimits.h'' defines the maximum number of opened files:

{{{
#   define MAX_FILE   32
}}}

If you need open more HDF4 files simultaneously you should change this value and rebuild HDF4 library (there is no need to rebuild GDAL if it is already compiled with HDF4 support).