is Parallel-NetCDF technically needed for CESM 2.1.1?

[kyle.clem]

Hello,

For some reason I have not been able to compile the default test case (--res f19_g17 --compset B1850) for CESM 2.1.1 on my local cluster, which was configured using various software modules that have been around on the cluster for a while. I suspect there are inconsistencies in the compilers used to build ZLIB, HDF5,..., CESM. So I am going to try to build all the software over again to ensure everything is consistent and try configuring/compiling CESM again using my own software.

So far I've successfully built ZLIB with gcc/8.2.0 and HDF5 with openmpi/3.1.5. However, for some reason I have not been able to build PnetCDF with openmpi/3.1.5 (I suspect it is an issue with our openmpi compiler). Therefore, I cannot enable pnetcdf when building NetCDF-C (i.e. --enable-parallel-tests --enable-pnetcdf).

So I am wondering...do I technically need pnetcdf (and subsequently, do I need pnetcdf enabled for NetCDF-C) to compile and run CESM 2.1.1? Or could I simply skip building pnetcdf and enabling pnetcdf for netcdf-c, and just carry on? I'm just not sure if this would potentially cause issues down the road when compiling and running CESM.

Thank you for any help and/or advice,
Kyle

 

[jedwards]

No you do not need pnetcdf or a parallel build of netcdf - however pnetcdf is by far the best performing interface in most cases, I would recommend opening an issue with pnetcdf to see if you can figure out the problem. Also CESM does not use the netcdf internal build of pnetcdf, you should build and link pnetcdf separately.

 

[kyle.clem]

Thanks for you reply. This is good to know. So I don't need to enable pnetcdf during the netcdf build. But to enable pnetcdf for CESM, I will need to add the pnetcdf path on the model level once I've sorted my issue building pnetcdf.

Two other quick questions:
1) Do you know off the top of your head where I will need to add these paths to link pnetcdf?
2) Also, is NCAR PIO (Parallel IO) needed??

 

[jedwards]

PIO is needed, it's included with the model. You just need to add the PNETCDF path to config_machines.xml

 

[kyle.clem]

So I don't need to build PIO myself and manually link it?

 

[jedwards]

No - have you followed the testing and porting guide? 6. Porting and validating CIME on a new platform — CIME ufs_release_v1.0 documentation

 

[kyle.clem]

Ah, I have been looking for something like this!! Thanks for sharing with me! And thanks for all your help.