Dear all,
I realize this may be more of a XIOS question than a NEMO one, but maybe somebody knows a simple answer.
With XIOS 2 (or 2.5), is it possible to choose the chunk size in the netcdf files ?
By default, the chunksize is equal to the grid size, and I would like to make smaller chunks.
With XIOS3 it seems possible, https://sites.nemo-ocean.io/draft-guide/xios3demo.html#chunking-and-compression
Thanks,
Luc
I don’t think the user had any control over chunksizes in XIOS2. That’s mostly guesswork since it is poorly documented, but the code in src/io/onetcdf4.cpp contains the comment:
// set chunksize : size of one record
// but must not be > 2GB (netcdf or HDF5 problem)
and the code around that doesn’t appear to offer any choice other than dimsizes. It wasn’t so much of an issue with XIOS2 because we tended to use multiple_file o/p for the larger models and rechunk at the rebuilding stage. It might be worth posting a query (issue) on the xios site: https://forge.ipsl.jussieu.fr/ioserver/ in case there is more subtlety in the C++ code than I’m seeing.