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use_netcdf_classic does not work when quilt server is used

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Dear all,

In testing WRF runs (3.7.1), the default output is in HDF5. Using the use_netcdf_classic=.true. option, the output format becomes "data" using the file command of Linux. However, if quilt servers are used by setting, say, nil_tasks_per_group=4, nio_groups=1, the output does not honoured the use_netcdf_classic flag and the format is fixed to HDF5.

Any clue?

best regards,

I can confirm that this is still an issue with 4.1.1. Without quilting, ncdump -k reports 64-bit offset, and the files are of constant size. With quilting, ncdump -k reports netCDF-4, and the files are much smaller and of variable size.
I will talk to our software engineer about this issue. I will keep you updated if I have any feedback.
This issue is likely related to the version of PNETCDF in place at your home institution. The quilting option means that a single file is written by multiple output processes, and this capability requires PNETCDF. The local implementation of PNETCDF probably uses the netcdf4+hdf5 library.