MOM compilation - symmetric vs nonsymmetric

[JosephMouallem]

While running the global coupled model with the latest source code updates and current build system, we encounter the following runtime error:

FATAL from PE 1559: dimension lonq in the file INPUT/MOM.res.nc is smaller than the size of the associated domain x axis.

After debugging, the issue appears to be related to how libmom6 is compiled.

• Compiling with:
  MOM6/config_src/memory/dynamic_symmetric is causing the issue in the global configuration.

• Compiling with:
  MOM6/config_src/memory/dynamic_nonsymmetric resolves the issue.

However, dynamic_symmetric is requires for the regional configuration, while dynamic_nonsymmetric is required for the global configuration.

Is it possible to support both configurations with a single compiled MOM6 library/workflow?

[lharris4]

I'd recommend getting in touch with the MOM6 folks about this. If this switch needs to be supported as a runtime capability, they should add it as one.

…

On Fri, Mar 27, 2026 at 3:58 AM JosephMouallem ***@***.***> wrote: *JosephMouallem* created an issue (NOAA-GFDL/SHiELD_build#80) <#80> While running the global coupled model with the latest source code updates and current build system, we encounter the following runtime error: FATAL from PE 1559: dimension lonq in the file INPUT/MOM.res.nc is smaller than the size of the associated domain x axis. After debugging, the issue appears to be related to how *libmom6* is compiled. - Compiling with: MOM6/config_src/memory/dynamic_symmetric is causing the issue in the global configuration. - Compiling with: MOM6/config_src/memory/dynamic_nonsymmetric resolves the issue. However, dynamic_symmetric is requires for the regional configuration, while dynamic_nonsymmetric is required for the global configuration. Is it possible to support both configurations with a single compiled MOM6 library/workflow? — Reply to this email directly, view it on GitHub <#80?email_source=notifications&email_token=AMUQRVBKEPJBE7ROMNML7XL4SWDU7A5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NBRGQ3DSNRTGM4DPJTSMVQXG33OVJZXKYTTMNZGSYTFMSSWK5TFNZ2KYZTPN52GK4S7MNWGSY3L>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AMUQRVAFM3O7PRN2ZI3QGKD4SWDU7AVCNFSM6AAAAACXA6XDBCVHI2DSMVQWIX3LMV43ASLTON2WKOZUGE2DMOJWGMZTQNY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[breichl]

Hi @JosephMouallem.

Two questions.

1. Where did the restart file you are trying to read in come from? Is it from a symmetric run or a nonsymmetric run? It seems it was created with a nonsymmetric executable. Could you create the restart with a symmetric executable, which should then also fix your issue?
2. Is this restart file issue the reason why you say "dynamic_nonsymmetric" is required for the global configuration? So that if you had a restart file created with symmetric memory, then you could run the global configuration with symmetric memory? Would that be a satisfactory solution?

I do not think it is an option to make the switch between symmetric/nonsymmetric memory a runtime option, since the memory allocation is controlled with compile time macros and thus would require a significant rewrite (and would result in less efficient/branching/repeating codes). But we can revisit that discussion if there is a reason that requires the nonsymmetric memory in global mode.

[JosephMouallem]

Hi @breichl, thanks for the info.
The restart files come from a SPEAR run, which looks like it is compiled with dynamics_nonsymmetric. I am not sure if we can recreate these files without recompiling and rerunning the original SPEAR setup.
In any case, I will double check which exec we used for the global forecast runs with glorys IC.
I think this issue is ok if it is only related to where the restart files came from in the first place.

[lharris4]

@breichl @JosephMouallem in that case, is it possible to run the regional domain with the nonsymmetric option, so that we can have one executable to handle both regional and global MOM6?

[JosephMouallem]

@lharris4 The OBCs in MOM6 only work with the symmetric option.