[Ncep.list.nems.announce] Comments Requested: Moving FMS out of MOM6 and FV3 repos

Samuel Trahan - NOAA Affiliate samuel.trahan at noaa.gov
Tue Aug 28 16:02:13 UTC 2018


The issue of how to put EMC repos in github while retaining EMC control has
already been solved by NOAA management.  There is a NOAA-EMC area in
github.  I'm using it to do pull requests to GFDL:


The master repository is here:


As you can see, GFDL already uses the solution suggested to us by upper

I cannot guess where the repository will be if DTC takes over management.

Sam Trahan

On Tue, Aug 28, 2018 at 10:41 AM, Rocky Dunlap - NOAA Affiliate <
rocky.dunlap at noaa.gov> wrote:

> A question here is how the distributed nature of Git, including local
> forks and pull requests, can be used to both meet the strict accessibility
> guidelines of NCO and at the same time promote EMC returning its ruggedized
> code back to GFDL and the rest of the community using FMS.
> Rocky
> On Tue, Aug 28, 2018 at 7:37 AM George Vandenberghe - NOAA Affiliate <
> george.vandenberghe at noaa.gov> wrote:
>> Given EMC's role in implementing and ruggedizing collaborators'  code for
>> production standards, it is essential that we not depend
>> on outside repositories which may or more likely will not be maintained
>> in accordance with our needs.  NCO
>> should note the requirement to get a critical component of FV3 from an
>> external repository every time they build
>> including for emergency bug mitigations (in the dark of night) and apart
>> from any other concerns (*And there are plenty of others*) NCO and PMB
>> should
>> absolutely veto using the GFDL repository for a production critical (and
>> especially for our flagship dynamic core!) code.
>> On Mon, Aug 27, 2018 at 9:47 PM, Samuel Trahan - NOAA Affiliate <
>> samuel.trahan at noaa.gov> wrote:
>>> Hi all,
>>> We have a proposed commit that is urgently needed, but may have major
>>> negative impacts to a lot of users.  Please read this email and comment.
>>> Our comment period ends at noon Tuesday, September 4.  The commit, if
>>> accepted, will happen Wednesday, September 5.
>>> *The Commit: Overview*
>>> In NEMS apps, the FMS exists within both the FV3 and MOM6 repositories;
>>> hence some apps have two copies of FMS.  We have a proposed commit that
>>> will move the FMS up one level so there is only one FMS per app.  The FMS
>>> we've chosen is the one from the GFDL repository.  The technical details of
>>> the changes, are largely inconsequential; the main issue is the choice of
>>> repositories.
>>> *Consequences*
>>> These are the consequences of choosing GFDL's FMS repository.
>>> 1. Portability changes to the FMS will be lost permanently because GFDL
>>> rejected them.  This means the FV3 GFS will not be usable except with
>>> certain versions of the Intel compiler.  This has been confirmed.
>>> 2. Recent and upcoming FMS bug fixes will be lost because they are not
>>> in the GFDL repository.
>>> 3. In general, any FV3 changes will have to wait several weeks if they
>>> need changes to FMS.
>>> Items #2 and #3 are unavoidable.  GFDL FMS has a large userbase and
>>> lengthy test process.  They will, out of necessity, have a long delay
>>> before commits.
>>> *Alternatives*
>>> I know of three alternatives to our FMS repository problem.  Any of
>>> these may require funding or tasking changes, in or from NOAA:
>>> 1. GFDL handles the FV3 GFS as a special case, maintaining a branch of
>>> FMS for the FV3 GFS, and applying changes within 2-3 days.  GFDL ports FMS
>>> to other compilers.
>>> 2. DTC maintains a fork of FMS which all NEMS apps use.  DTC maintains
>>> any portability changes and regularly pulls changes from GFDL FMS.  They
>>> receive any changes needed for NEMS coupling and resolve conflicts as
>>> needed.
>>> 3. EMC maintains the aforementioned fork.
>>> Note that DTC is presently tasked with porting the FMS, and has
>>> successfully ported it to other platforms and maintained an FMS repository.
>>> *The Branches*
>>> The changes can be found in the "fms-component" branches of the
>>> NEMSfv3gfs and EMC_FV3-MOM6-CICE5 repositories.  These will be updated
>>> later this week when incoming FV3 changes are available.  We will be sure
>>> to test before committing to the relevant branches.
>>> When testing this yourself, note that the EMC_FV3-MOM6-CICE5 warm start
>>> test will not reliably reproduce itself; this is a known issue that is
>>> unrelated to this commit.  Jet baselines are out-of-date, so you cannot
>>> test there.  All other tests should pass for both apps on all supported
>>> platforms.
>>> *The Commit: Details*
>>> Overview of the changes:
>>> 1. FMS is removed from the build system in MOM6 and FV3
>>> 2. FMS is added at the app level from git://github.com/NOAA-GFDL/FMS.
>>> The "git" url makes this submodule read-only.  That is a workaround for
>>> problems in the installation of "git" on WCOSS Cray and Dell which make
>>> github unreachable via https.  This "git" installation problem has been a
>>> known issue for several months and remains unresolved, so such a workaround
>>> is necessary.
>>> 3. The FMS/fv3gfs directory is updated to be able to build FMS outside
>>> of FV3.  This change was accepted by GFDL in their repository.
>>> 4. The NEMSAppBuilder is updated to build FMS.  It is treated the same
>>> way as a coupled component in the build system.
>>> 5. Any appBuilder files must include FMS before FV3 or MOM6 in their
>>> component list.
>>> 6. The NEMSfv3gfs tests/compile.sh is updated to build FMS before FV3.
>>> Sincerely,
>>> Sam Trahan
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