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Software stacks

The LUMI software stacks contain the software already installed on LUMI. The software stacks are made available through the LMOD module environment.


On LUMI, three types of software stacks are currently offered:

  • CrayEnv offers the Cray Programming Environment (PE) and allows one to use it completely in the way intended by HPE-Cray. The environment also offers a limited selection of additional tools, often in updated versions compared to what SUSE Linux, the basis of the Cray Linux environment, offers. If you need a richer environment, you should use our other software stacks.

  • LUMI is an extensible software stack mostly managed through EasyBuild. You can read more about EasyBuild on LUMI on the "Easybuild" page in the "Software" section. Each version of the LUMI software stack is based on the version of the Cray Programming Environment with the same version number.

    A deliberate choice was made to only offer a limited number of software packages in the globally installed stack as the setup of redundancy on LUMI makes it difficult to update the stack in a way that is guaranteed to not affect running jobs and as a large central stack is also hard to manage. However, the EasyBuild setup is such that users can easily install additional software in their home or project directory using EasyBuild build recipes that we provide or they develop, and that software will fully integrate in the central stack (even the corresponding modules will be made available automatically).

  • spack is an extensible software stack based on the Spack package manager. You can read more about Spack on LUMI on the "Spack" page in the "Software" section. Spack is offered "as-is" for users experienced in the use of Spack, but properly pre-configured to use compilers and some libraries already installed on the system. The LUMI User Support Team does not implement new Spack packages or debug build recipes for existing ones.

Selecting the software stack

Running module avail on a fresh shell will show a list like:

$ module avail

... some lines removed here

-------------------------- HPE-Cray PE modules ----------------------------
   PrgEnv-amd/8.4.0              (D)

... some lines removed here

----------------------------- Software stacks -----------------------------
   CrayEnv    (S)      LUMI/23.03  (S)    spack/22.08-2
   LUMI/22.08 (S,D)    LUMI/23.09  (S)    spack/23.03
   LUMI/22.12 (S)      spack/22.08        spack/23.03-2 (D)

--------------------- Modify the module display style ---------------------
   ModuleColour/off      (S)        ModuleLabel/PEhierarchy (S)
   ModuleColour/on       (S,D)      ModuleLabel/system      (S)
   ModuleExtensions/hide (S)        ModulePowerUser/LUMI    (S)
   ModuleExtensions/show (S,D)      ModuleStyle/default
   ModuleLabel/label     (S,L,D)    ModuleStyle/reset       (D)

-------------------------- System initialisation --------------------------
   init-lumi/0.2 (S,L)

------------------------- Non-PE HPE-Cray modules -------------------------

... some lines removed here

------------------- This is a list of module extensions -------------------
    rclone (E)     restic (E)     s3cmd (E)

... some lines removed here

The first block(s) in the output are the modules available through the default software stack.

The Software stacks block in the output shows the available software stacks: CrayEnv, 4 versions of the LUMI stack and 4 versions of the spack stack in this example. The (S) besides the name shows that these are sticky modules that won't be removed by default by module purge. This is done to enable you to quickly clean your environment without having to re-initialize from scratch. In the future we may mark some stacks also with LTS next to their name which would then denote that this is a release that we will try to support long-term (ideally two years), but currently the system is changing too rapidly (as some of the hardware is new and not an evolution of previous hardware) so we cannot guarantee any level of longevity for any of the software stacks. In fact, experience has shown that we may have to remove a stack after a year or so.

The next block, titled Modify the module display style, contains several modules that can be used to change the way the module tree is displayed:

  • ModuleColour: these modules can be used to turn the color on or off in the module display.
  • ModuleLabel: change the way the modules are subdivided in blocks and the way those blocks are presented.
  • ModuleLabel/label is the default and will collapse related groups of modules in single blocks, including the Cray PE modules.
  • ModuleLabel/PEhierarchy: will still use the user-friendly style of labeling but will show the complete hierarchy in the modules of the Cray PE.
  • ModuleLabel/system: does not use the user-friendly label texts, but shows the path of the module directory instead.
  • ModulePowerUser: will also reveal several hidden modules, most of which are only important to sysadmins or users who really want to do EasyBuild development in a clone of the software stack.
  • ModuleExtensions/hide and ModuleExtensions/show are used to hide or show the module extensions at the end of the overview of module avail.


Loading CrayEnv will essentially give you the default Cray environment enriched with several additional tools. The CrayEnv module will try to detect the node type of LUMI it is running on and load an appropriate set of target architecture modules to configure the Cray PE (see the documentation page on the programming environment in the Development section). Executing a module purge while working in the CrayEnv environment will automatically reload that module and restore the target architecture modules to a set suitable for the node type you are working on.


LUMI is our main software stack, managed mostly with EasyBuild. It contains software build with the system compiler and the PrgEnv-gnu, PrgEnv-cray, PrgEnv-aocc and PrgEnv-amd programming environments, which includes Cray MPI and the Cray scientific libraries. As mixing compiler versions and library versions is dangerous, the stack is organized in versions that correspond to the version of the Cray PE used to compile the software. Some versions may have the extension .dev which denotes that they are highly experimental and under development, and may completely change or disappear at some point.

The LUMI software stack is activated by loading the desired version of the LUMI module, e.g.,

module load LUMI/23.09

The LUMI module will try to detect the node type it is running on and will automatically select the software stack for the node type by automatically loading a partition module. However, that choice can always be overwritten by loading another partition module, and this can even be done in a single command, e.g.,

module load LUMI/23.09 partition/L

will load the software stack for the login nodes (which in fact will also work on the compute nodes and data analysis and visualization nodes).

partition/L and LUMI-C compute nodes

Software in partition/L can be used on the compute nodes also and there is even some MPI-based software already installed in that partition. However, software compiled in partition/C may offer better performance on the compute nodes of LUMI-C as software in that partition is specifically optimized for the zen3 "Milan" CPUs in those nodes.

Running MPI programs is not supported on the login nodes, but those modules may still contain useful pre- or postprocessing software that can be used on the login nodes.

Once loaded, you will be presented with a lot of modules in a flat naming scheme. This means that all software available in that version of the LUMI software stack will be shown by module avail (except for hidden modules for software that we deem most users may not directly load). However, not any combination of modules can be loaded together. In particular, software compiled with different programming environments cannot be used together. There are five types of modules:

  • The module version contains (with the version of the LUMI stack): The package is compiled with the PrgEnv-gnu programming environment.

  • The module version contains The package is compiled with the PrgEnv-cray programming environment.

  • The module version contains The package is compiled with the PrgEnv-aocc programming environment, the AMD compilers for CPU-only work (hence available only on LUMI-C, LUMI-D and the login nodes)

  • The module version contains The package is compiled with the PrgEnv-AMD programming environment, the Cray wrapper around the AMD ROCm compilers. This environment will only be offered on LUMI-G.

  • The name contains neither of those: The package is compiled with the system gcc compiler, something that is only done for software that is not performance-critical like some build tools and workflow tools.

In EasyBuild, cpeGNU, cpeCray, cpeAOCC and cpeAMD are called toolchains, a set of compatible compilers, MPI and mathematical libraries. Software compiled with the system compiler is also called software compiled with the system toolchain, which is a restricted toolchain that only contains the compiler that comes with the operating system. Software compiled with different cpe* toolchains cannot be loaded at the same time but can be loaded together with software compiled with the SYSTEM toolchain. The module system currently does not protect you against making such mistakes! However, software may fail to work properly.

Issue: Missing programming environments

When we retire a programming environment from the system, the corresponding LUMI module may remain available for a while with some tricks under the hood so that software already compiled for that version of the LUMI module would mostly still run. However, no new compilations should be done with such a toolchain, and we cannot guarantee that all software will still run (and know for sure that some software will not run anymore due to the way it is linked against libraries).

Adding additional software to the LUMI software stack

The LUMI software stack itself cannot offer all software to all users as that would be both confusing (certainly as sometimes customizations are expected) and impossible to maintain (as it would not be clear when software can be removed and no longer needs to be updated). Therefore, the LUMI software stack can be extended with software installed in the user's space through EasyBuild in a way that is 100% compatible with the system stack. That software will be automatically visible when loading the LUMI module.

The LUMI Software Library provides an overview of all software that is either available pre-installed on the system or can be user-installed via EasyBuild using recipes developed by LUST and partners in the LUMI project (and instructions for some software that is unsuitable for installation through EasyBuild).

The default location for user-installed software in $HOME/EasyBuild. However, we advise installing software in the /project directory of the project instead so that a single software installation can be used by all members of the project. This is done by pointing the environment variable EBU_USER_PREFIX to the software installation directory, e.g.,

export EBU_USER_PREFIX=/project/project_465000000

It is a good idea to do this in your .profile or .bashrc file. This will enable the LUMI modules to also find the software installed in that directory.

Loading the EasyBuild-user module will enable installing software with EasyBuild for the current version of the LUMI software stack and current node type (partition module).

See the Easybuild page for more information about installing software using Easybuild.