Dear NCAS-CMS helpdesk, Further to CMS helpdesk message last week, I am running an extra set of simulations with the interactive stratospheric aerosol configuration of GA4 UM-UKCA, The reason we’re running “the old” GA4 UM-UKCA is to complete our submission for the Hunga Tonga MIP, and aligned t…

Hi Graham, Having to lower the compiler optimisation level on a particular file for the model to run is not uncommon and is something we often do when porting UM versions or with a change of compiler version. By process of elimination, setting -O0 on groups of files in the compile override file, y…

I’d just add a point that you have a core dump, so if you want to see which sections of the code should have their compiler settings changed you can use gdb. I don’t have access to your core file, but the commands would be: cd /work/n02/n02/gmann/um/xqjhx gdb bin/xqjhx.exe core bt full and so o…

[image] dcase: gdb bin/xqjhx.exe Hi Ros, Dave, Thanks for sending this info, and ah OK re: sometimes it being a bit of “trial and error” to track this down. Dave – thanks for this info re: the gdb commands, and that’s great. I did refer to the info on the ARCHER debug tools page ( Debugging…

Do put -g because it includes the symbol table, so your debugger can ‘read’ the code and match it to source files. This will tell you which line you segfault on and you should be able to see which variable is going out of bounds etc. The -O0,1,2,… is the optimisation level. It sounds like the compi…

V8.4 GA4 UM-UKCA ARCHER2 job seg-faulting, but runs OK with debug option on cce compiler (but obviously very slowly with debug and O0)

Unified Model

RosalynHatcher 2 June 2026 19:38 7

See follow-up here:
Found cause of the ARCHER2 UMv8.4 GA4 UM-UKCA seg-fault – now runs fine (JULES routine “snow.F90”)

Topic		Replies	Views
Found cause of the ARCHER2 UMv8.4 GA4 UM-UKCA seg-fault -- now runs fine (JULES routine "snow.F90") Unified Model ARCHER2	0	14	2 June 2026
Previous working-job now seg-faulting on 1st timestep after OS upgrade (ARCHER2 v8.4 GA4 UM-UKCA) Unified Model ARCHER2 , PUMATest	37	614	19 December 2023
Segmentation fault (core dumped) Unified Model ARCHER2	0	31	14 November 2025
Submit-failed Unified Model ARCHER2 , PUMATest	25	895	2 September 2022
Compilation Time-Limit exceedance on ARCHER2 re: v8.4 GA4 UM-UKCA Unified Model ARCHER2	4	172	18 September 2023

V8.4 GA4 UM-UKCA ARCHER2 job seg-faulting, but runs OK with debug option on cce compiler (but obviously very slowly with debug and O0)

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