Friendly User Testing

Thanks for your interest in our new file format work. Here's the rundown:

Getting the Source

Getting and building the snapshot is easy: we committed it to pnetcdf trunk in r632, so get it just as you would any other "latest svn" update:

$ svn co https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk/ parallel-netcdf
$ autoreconf
$ configure && make && make install

Using the new Format

When you create a netcdf dataset with parallel-netcdf, add the flag NC_64BIT_DATA to the mode passed in to ncmpi_create(). Do not pass in the flag NC_64BIT_OFFSET. The two are mutually exclusive.

Reporting Results

Please send along any success or failure reports to the parallel-netcdf mailing list (parallel-netcdf@…).

Known Issues

• A dimension with more than 2³¹ elements will overflow MPI_Type_create_subarray. This is a limitation in MPI. Will have to figure out a workaround This was fixed in r622
• Serial netcdf libraries and tools will not know how to operate on this file format (yet). The serial netcdf team knows about our work and will accept patches once we have done the work to teach serial netcdf how to deal with this new file format.
• If you specify both NC_64BIT_OFFSET (CDF-2) and NC_64BIT_DATA (CDF-5), only NC_64BIT_OFFSET will be honored.