Guidance After Pitzer Upgrade to RHEL9

We upgraded the operating system on the Pitzer cluster from RHEL7 to RHEL9 on July 28 2025. This upgrade introduces several software-related changes compared to the RHEL7 environment used on the Pitzer and provides access to modern tools and libraries but may also require adjustments to your workflows. Please refer to

• Pitzer Software Environment on RHEL 9 for key software changes and available software
• Pitzer Programming Environment on RHEL 9 for details on compiler commands, parallel and GPU computing

Key changes

• PBS compatibility layer provided by Slurm is disabled so you need to convert your PBS batch scripts to Slurm scripts. See this Slurm migration page for more guidance. 
• You are now required to specify the module version when loading any modules. For example, instead of using module load intel, you must use module load intel/2021.10.0. Failure to specify the version will result in an error message. Below is an example message when loading gcc without specifying the version:

  $ module load gcc
  Lmod has detected the following error:  These module(s) or extension(s) exist but cannot be loaded as requested: "gcc".
  
  You encountered this error for one of the following reasons:
  1. Missing version specification: On Ascend, you must specify an available version.
  2. Missing required modules: Ensure you have loaded the appropriate compiler and MPI modules.
  
  Try: "module spider gcc" to view available versions or required modules.
  
  If you need further assistance, please contact oschelp@osc.edu with the subject line "lmod error: gcc"