Slow execution of nccopy from netcdf 4.6.3

Problem

nccopy from netcdf version 4.6.3 becomes very slow when transforming a classical netcdf formatted file into a file with internal compression. The reason is that the information on the default chunk size is lost.

Solution

Either:

• use netcdf 4.4.1.1 or netcdf 4.7.x.
• deliver the chunk size explicitly. For details and an example, see the discussion on github!