How to make libIGCM use links instead of copies of the boundary files

WARNING: This has only be tested for obelix, prescribing a RUN_DIR (i.e. not using the default run dir location)

1. Place the attached file in the modipsl/libIGCM folder.

2. Then apply the modifications with this command

   patch -p0 < libigcm_link.patch
   

3. In order to use

Go to the Job_xxxxx file and add "ln" behind IGCM_comp_GetInputBoundaryFiles:

#D-
# ------------------------------------------------------------------
#D-   4.6 GET BOUNDARIES CONDITIONS
#D-       - (SST, WIND[X,Y,Z], LAI ...)
#D-       - READ AND USE BY GCM AT EACH EXECUTION.
# ------------------------------------------------------------------
IGCM_comp_GetInputBoundaryFiles "ln"

This will change the behaviour from copy files to create a link for Boundary Files.

4. To restore the original behaviour, remove "ln".

Performance

ORCHIDEE-CNP, 2x2 degree forcing file, 64 procs on obelix.

(1) For the "spinup"-style of ORCHIDEE-CNP simulation (min. number of boundary files) I found a 7.5% reduction (15 seconds) in time needed to compute a single model year.

(2) For the default-style of ORCHIDEE-CNP simulation (max. number of boundary files) I found a 17% reduction (22 seconds) in time needed to compute a single model year.