Change default IO type from NETCDF4C to PNETCDF by amametjanov · Pull Request #325 · E3SM-Project/Omega

amametjanov · 2025-12-08T20:23:29Z

Change default IO type from NETCDF4C to PNETCDF

Checklist

Fixes #333
Closes #334

amametjanov · 2025-12-08T20:24:43Z

Testing:

aurora+oneapi-ifxgpu: 100% tests passed, 0 tests failed out of 35
frontier:
- craygnu: 100% tests passed
- craygnu-mphipcc: 100%
- craycray: 80% tests passed, 7 tests failed out of 35 (unrelated to IO)
- craycray-mphipcc: 100%
- crayamd: 100%
- crayamd-mphipcc: 100%
pm:
- gnu: 100%
- intel: 100%
- gnugpu: 100%
chrysalis:
- intel: 100%
- gnu: 100%

xylar · 2025-12-09T12:28:18Z

Thanks very much, @amametjanov! This looks promising.

xylar · 2025-12-09T15:28:29Z

@amametjanov, I've got 3 tests for this in the queue, one on Chrysalis and 2 on Frontier. But wait times seem to be a bit long both places. I'll keep you posted.

amametjanov · 2025-12-09T19:15:00Z

To fix IO_Test ctest, this PR needs scorpio PR #670, which expands supports for CDF5 data-types (like 64-bit ints).

xylar · 2025-12-09T22:21:30Z

@amametjanov, maybe this will be fixed by E3SM-Project/scorpio#670 but what I'm seeing on Chrysalis with this branch is:

PIO: FATAL ERROR: Aborting... An error occured, Waiting on pending requests on file (output.nc, ncid=21) failed (Number of pending requests on file = 1, Number of variables with pending requests = 1, Number of request blocks = 1, Current block being waited on = 0, Number of requests in current block = 1).. NetCDF: Operation not allowed in define mode (err=-39). Aborting since the error handler was set to PIO_INTERNAL_ERROR... (/home/ac.xylar/e3sm_work/e3sm/azamat/mod-dflt-io-type/externals/scorpio/src/clib/pio_darray_int.cpp: 2192)

The polaris output is available at:

/lcrc/group/e3sm/ac.xylar/polaris_0.9/chrysalis/test_20251209/omega-pr-mod-dflt-io-type

It seems like this won't be a short-term fix for Omega if a scoprio fix is needed, because that would mean:

scorpio fix gets merge
scorpio release happens
scorpio gets update in E3SM
E3SM/master gets merged into Omega/develop
This branch goes in

It feels like we should look into whether there's some alternative way to address #323 in the next week or two.

Update scorpio from v1.8.2 2025-Jul-14 to v1.9.0 2025-Nov-21. Also add fix for PnetCDF CDF5 types.

amametjanov · 2025-12-21T23:26:03Z

Xylar, please check with updated head of this branch to see if it fixes NetCDF: Operation not allowed in define mode errors in polaris tests. All ctests are passing for me.

This branch updates the scorpio submodule ahead of E3SM/master's version, which is still on v1.8.2 2025-Jul-14. When scorpio gets update in E3SM/master (with v1.9.0 or later), E3SM/master merge to Omega/develop will subsume this branch's updates.

xylar · 2025-12-22T11:59:41Z

Thanks, @amametjanov! I'll retest as soon as I can.

xylar

I tested the omega_pr suite using the fix in E3SM-Project/polaris#442, pointing to this branch for the Omega build.

I was able to run successfully with both Intel and Gnu on Chrysalis. I discovered that I can't log in to either Aurora or Frontier at the moment. I'm trying on Perlmutter (CPU and GPU) next.

In the mean time, two small questions/comments.

xylar · 2026-01-05T13:26:05Z

On Perlmutter-CPU (Both Intel and Gnu) and -GPU (Gnu-GPU), I'm seeing the same hanging behavior reported in E3SM-Project/polaris#396 as we had seen previously. It seems like maybe that behavior is unfortunately independent of this PIO problem.

grnydawn · 2026-01-14T20:09:37Z

@amametjanov , I ran the tests for this PR on Frontier, but I got the same PIO error:

PIO: FATAL ERROR: Aborting... invalid IO type (/lustre/orion/cli115/scratch/grnydawn/cronjobs/tasks/polaris_cdash/polaris/e3sm_submodules/Omega/externals/scorpio/src/clib/pio_lists.cpp: 120)

Please see Frontier test results at Omega CDash dashboard at https://my.cdash.org/index.php?project=omega

Also, address GH-review comments.

xylar · 2026-01-27T13:49:30Z

@amametjanov, could you please let me know when this is ready for me to re-test in Polaris?

amametjanov · 2026-01-27T17:45:19Z

Yes, this is ready, please re-run Polaris tests. 🙏

xylar · 2026-01-29T14:21:45Z

Testing

I successfully ran the omega_pr suite from Polaris using this branch and:

(Unchecked items are still in the queue -- update soon...)

I also verified that one output.nc file produced by Omega was in cdf5 format, as expected. I presume the same will be true for all files.

@amametjanov and @grnydawn, thank you so much for figuring out these issues and fixing them!

xylar · 2026-01-29T16:31:28Z

My Frontier tests are now running. All the CPU tests did okay. The GPU tests are very slow by comparison, and they are taking more than the 1 hour I had allocated. I don't know for sure but I presume the slowness is not from this PR.

I also saw the I/O failure in one craygnu-mphipcc test: ocean/planar/manufactured_solution/convergence_both/del2. It is discouraging that I am seeing this failure but the situation is clearly far better than it was before.

I will rerun both the tests that timed out and the one that failed. We will see what happens.

Update: It seems like the file system on Frontier might be a problem. My resubmitted jobs are hanging just trying to load the environment.

xylar · 2026-01-29T16:52:02Z

In the crayamd-mphipcc run on Frontier, I'm seeing a different error after trying to rerun following a timeout:

PIO: FATAL ERROR: Aborting... FATAL ERROR: NetCDF: Operation not allowed in data mode (file = output.nc) (/ccs/home/xylar/e3sm_work/Omega/azamat/mod-dflt-io-type/externals/scorpio/src/clib/pio_getput_int.cpp: 544)

This is for the ocean/spherical/icos/rotation_2d test case.

xylar · 2026-01-29T16:57:58Z

When I try to rerun the failed test ( ocean/planar/manufactured_solution/convergence_both/del2) for craygnu-mphipcc, I see a different error:

PIO: FATAL ERROR: Aborting... FATAL ERROR: NetCDF: Unknown file format (file = output.nc) (/ccs/home/xylar/e3sm_work/Omega/azamat/mod-dflt-io-type/externals/scorpio/src/clib/pioc_support.cpp: 5503)

The original error was the same as we have seen before:

PIO: FATAL ERROR: Aborting... invalid IO type (/ccs/home/xylar/e3sm_work/Omega/azamat/mod-dflt-io-type/externals/scorpio/src/clib/pio_lists.cpp: 120)

I presume these errors might indicate that Omega isn't overwriting the output.nc file as expected if a run either times out or fails. If so, that issue would presumably be beyond the scope of this PR.

rljacob · 2026-01-29T16:58:46Z

For Frontier, craygnu and craygnu-mphipcc is the only compiler E3SM cares about. Don't spend more then a token amount of E3SM time looking that the others.

xylar · 2026-01-29T16:59:33Z

Okay, thanks @rljacob. That wasn't clear to me.

xylar · 2026-01-29T17:54:25Z

I set up ocean/planar/manufactured_solution/convergence_both/del2 and reran it with craygnu-mphipcc, this time successfully, so the problem there seems to be transient.

xylar · 2026-01-29T18:23:00Z

Nope, now I'm seeing the usual error message:

PIO: FATAL ERROR: Aborting... invalid IO type (/ccs/home/xylar/e3sm_work/Omega/azamat/mod-dflt-io-type/externals/scorpio/src/clib/pio_lists.cpp: 120)

but this time in the ocean/planar/manufactured_solution/convergence_both/default (again with craygnu-mphipcc).

So I think this PR should go in but we can't consider this problem to be solved.

amametjanov · 2026-01-29T21:13:14Z

Thank you for re-running Polaris tests (and merging).
I re-ran omega ctests on latest post-merge develop with all 6 frontier compilers and saw just 2 ctests fail with craycray on cpus; all others pass:

11 - HORZOPERATORS_PLANE_TEST and 12 - HORZOPERATORS_SPHERE_TEST

I heard that frontier scratch filesystem was hanging and slow this week: maybe that's the culprit.

This merge updates the e3sm_submodules/Omega submodule from [f2e951a](https://github.com/E3SM-Project/Omega/tree/f2e951a) to [fc53608](https://github.com/E3SM-Project/Omega/tree/fc53608). This update includes the following MPAS-Ocean and MPAS-Frameworks PRs (check mark indicates bit-for-bit with previous PR in the list): - [ ] (ocn) E3SM-Project/Omega#325 - [ ] (ocn) E3SM-Project/Omega#329

Revert "Update scorpio" This reverts commit dfcffe1. We should not have updated an external submodule directly in Omega in #325 (my mistake!). Instead, we need to bring in changes like this scorpio update via merging E3SM/master into Omega/develop. I will follow up immediately with such a merge.

Change default IO type from NETCDF4C to PNETCDF

200a89a

amametjanov mentioned this pull request Dec 8, 2025

PIO errors with Gnu on many machines #323

Closed

amametjanov added 2 commits December 21, 2025 22:49

Update scorpio

dfcffe1

Update scorpio from v1.8.2 2025-Jul-14 to v1.9.0 2025-Nov-21. Also add fix for PnetCDF CDF5 types.

Add end-define-mode calls while in data-mode netcdf writes

e68388f

amametjanov force-pushed the azamat/mod-dflt-io-type branch from 4d44424 to e68388f Compare December 21, 2025 23:03

amametjanov marked this pull request as ready for review December 21, 2025 23:26

amametjanov added the Omega label Dec 21, 2025

amametjanov requested a review from xylar December 21, 2025 23:27

xylar reviewed Jan 5, 2026

View reviewed changes

Comment thread components/omega/configs/Default.yml Outdated

Comment thread components/omega/src/base/IO.cpp Outdated

xylar mentioned this pull request Jan 5, 2026

Omega on pm-cpu and -gpu hanging and crashing E3SM-Project/polaris#396

Closed

amametjanov and others added 3 commits January 24, 2026 02:59

Remove colon from ocn.hist.$SimTime for MPI-IO on Frontier

c3d275c

Also, address GH-review comments.

Update netcdf4->pnetcdf in default yaml and if no io-yaml exists

b58353f

fix a bug in reading IODefaultFormat from omega.yml

a237a9d

grnydawn mentioned this pull request Jan 28, 2026

fix a bug in reading IODefaultFormat from omega.yml #334

Closed

xylar added the bug Something isn't working label Jan 29, 2026

xylar self-assigned this Jan 29, 2026

xylar mentioned this pull request Jan 29, 2026

Modify Omega suites E3SM-Project/polaris#455

Merged

xylar merged commit 1b5cc62 into develop Jan 29, 2026
1 check passed

xylar deleted the azamat/mod-dflt-io-type branch January 29, 2026 18:24

xylar mentioned this pull request Feb 2, 2026

Update Omega submodule E3SM-Project/polaris#457

Merged

2 tasks

xylar mentioned this pull request Mar 13, 2026

Revert "Update scorpio" #360

Merged

8 tasks

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