OS-Upgrade of Fritz from AlmaLinux8 to AlmaLinux9

We will be upgrading the operating system on the Fritz cluster from AlmaLinux 8 to AlmaLinux 9. That means you will have to adapt your jobs. Most development and application software provided by us as “modules” is updated to current versions, old versions will usually no longer be available unless there is a good reason for that. If you compiled software yourself, you will need to recompile, as the version of libraries provided by the OS or our modules will change significantly.

The update will happen gradually over the course of the next month, that means the number of nodes running AlmaLinux 9 will gradually increase, while the number of nodes still running AlmaLinux 8 will be reduced further and further until there are none left. We recommend to switch to the AlmaLinux 9 nodes as soon as possible.

Currently, connecting to fritz.nhr.fau.de will take you to one of the AlmaLinux 8 login nodes. From Monday, June 08, you can instead connect to fritz9.nhr.fau.de to test the new AlmaLinux 9 login nodes. Then, from June 22, fritz.nhr.fau.de will lead to the AlmaLinux 9 login nodes, and the old AlmaLinux 8 login nodes will no longer be available.

Timeline

The timeline is currently planned as follows:

• 2026-06-08: fritz9.nhr.fau.de is available as AlmaLinux 9 login node for testing.
• 2026-06-22: fritz.nhr.fau.de now points to the AlmaLinux 9 login nodes, i.e. AlmaLinux 9 becomes the default. AlmaLinux 8 login nodes turned off. AlmaLinux 8 jobs already queued will still be processed, but slower and slower.
• beginning of July: no more AlmaLinux 8 nodes are remaining, with the exception of the visualization node fviz1.
• beginning of July: visualization node fviz1 gets reinstalled with AlmaLinux 9. This is expected to take a while due to the complexity of its software-stack, so it will not available for a few days.

We will keep this post updated.

Testing the AlmaLinux9 environment

To already test the new software environment from Monday June 08, simply connect to fritz9.nhr.fau.de instead of fritz.nhr.fau.de. This frontend has the new AlmaLinux 9 environment. You probably need to adapt your SSH-config to connect (copy the entry for “fritz” into a new one for “fritz9”).

To submit jobs to run under AlmaLinux 9, you need to add -C el9 or --constraint=el9 to your Slurm commandline. (If you need additional constraints like e.g. hwperf, you need to concatenate them with an ampersand, i.e. -C el9&hwperf.)