When you need to make a new mpas*.part.N file because you changed the number of nodes an MPAS component runs on. These instructions including adding the file to the repo for others to use.
Step-by-step guide
- See if "metis" or "gpmetis" is available on your platform and add it to your path.
- On Cray systems, gpmetis is available after `module load metis`.
- Do "module spider metis" to find the module to load.
- Find the base mpas graph file called "mpas-cice.graph.info.151020" or "mpas-o.graph.info.151031". These files should be in inputdata/ice/mpas-cice and inputdata/ocn/mpas-ocn respectively.
- Run the metis command with the last argument being the number of nodes for the partition.
- Example: "gpmetis mpas-cice.graph.info.151010 120" will generate a *.part.120 file for mpas-cice.
- Place the new file in the correct inputdata subdirectory for the model to find it.
Bonus round: Making better load balanced graph files for MPAS-Seaice
MPAS-Seaice is rather poorly load balanced with standard MPAS graph partitions. This is because sea ice only exists in a very limited part of the domain. A script has been written that can generate somewhat better partitions. Each block is split into 3 non-contiguous sections: One for each polar region and a larger one for the equatorial region. For highly desired changes to this script contact Adrian Turner.
- Download the MPAS-Tools repo.
- Install the mesh conversion tools (MPAS-Tools/grid_gen/mesh_conversion_tools)
- Ensure that your python build includes the netCDF4 library (http://unidata.github.io/netcdf4-python/)
- Run the sea ice graph generation script (MPAS-Tools/grid_gen/seaice_grid_tools)
usage: gen_seaice_mesh_partition.py [-h] -m MESHFILENAME -n NPROCS
[-c MPASCULLERLOCATION] [-o OUTPUTPREFIX]
[-p] [-g METIS]
Create sea ice grid partition
optional arguments:
-h, --help show this help message and exit
-m MESHFILENAME, --mesh MESHFILENAME
MPAS mesh file
-n NPROCS, --nprocs NPROCS
number of processors
-c MPASCULLERLOCATION, --culler MPASCULLERLOCATION
location of cell culler
-o OUTPUTPREFIX, --outprefix OUTPUTPREFIX
output graph file prefic
-p, --plotting create diagnostic plotting file of partitions
-g METIS, --metis METIS
name of metis utility