When trying to run the AMM12 with XIOS and the latest merge code (dev_MERGE_2013) I get bizarre failures.

Wihtout key_iomput the model runs fine for 10 days.

With key_iomput things fail. Using the standard iodef.xml file (which I have just recently amended to fit the new XIOS formatting requirements) from the CONFIG/AMM12/EXP00 directory the model should output both daily and every 5 days. It runs until one timestep before the end of the fifth day and gives the following error message; xios/src/output/onetcdf4.cpp', line 79 -> [ status = -60 ] NetCDF: Numeric conversion not representable Output files are created for both 1d and 5d, but when trying to view them or dump them an error message appears stating that they aren't netcdf format.

Have I 'fixed' the file format incorrectly, or is there something else going on?

XIOS will hang when NEMO is not run with MPP. I had committed a fix for this that apparently did not make it to v3.6 alpha, see #1157.

I propose the same fix as in [1157], including the C1D fix if no-one minds.

Context

Building coupled configuration UM + NEMO4 with XIOS2.5 (rev 1849 trunk) results in model hanging in OASIS just before ending OASIS definition stage.

Analysis

In our configuration adding a call to a new XIOS function (introduced in rev 1587) xios_oasis_enddef() just before oasis_enddef resolved the issue. This is the message from XIOS mail list on this subject.

     Revision: 1587
     ?http://forge.ipsl.jussieu.fr/ioserver/changeset/1587
     Author: ? ymipsl
     Date: ? ? 2018-10-15 16:42:33 +0200 (Mon, 15 Oct 2018)
     Log Message:
     -----------
     XIOS - OASIS interaction : due to many problem occurring in the
     oasis/XIOS initialization phase due to a bad order of
     intialization call ?from both, you have now the possibily to
     explicitly inform xios that the servers must call oasis_enddef().
     ** New rules : On model side, before calling oasis_enddef, you
     must add a call to "xios_oasis_enddef()"
     ** Old rules : oasis_enddef must be call before any call to
     "xios_context_initialize" otherwise it may lead to a deadlock.
     You can use the old rules if the variable <call_oasis_enddef> is
     set to false (default value is true), and by this way no need to
     modify the source code of the models

At the MetOffice? for XIOS2.5 compilation we have to use the latest available Cray compiler - cce/8.7.7.

At this moment it's not obvious if this problem is related to compiler we are using (it's not our default compiler); we may be able to test a different coupled configuration built with Intel compiler within couple of weeks.

As long as XIOS2.5 is at least at rev 1587 this change is neutral. There is a branch with the change (for NEMO 3.6), currently in review, to be implemented in MO package branch: ​http://forge.ipsl.jussieu.fr/nemo/changeset?sfp_email=&sfph_mail=&reponame=&new=12796%40branches%2FUKMO%2Fdev_r5518_GO6_XIOS25_cpl&old=12407%40branches%2FUKMO%2Fdev_r5518_GO6_package

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