[Ncep.list.nems.announce] Comments Requested: Moving FMS out of MOM6 and FV3 repos
Cecelia DeLuca - NOAA Affiliate
cecelia.deluca at noaa.gov
Tue Aug 28 15:58:20 UTC 2018
Hi Sam, if this is true: This means the FV3 GFS will not be usable except
with certain versions of the Intel compiler.
I think the policies here require management attention before taking next
steps..
Thanks,
Cecelia
On Mon, Aug 27, 2018 at 7:47 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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