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Work in progress

(30 April 2025)

The contents of this tutorial are currently being reworked to be up-to-date with recent developments in CernVM-FS, and to be well integrated in the EESSI documentation.

It is based on the "Best Practices for CernVM-FS in HPC" tutorial that was held on 4 Dec 2023, see also https://multixscale.github.io/cvmfs-tutorial-hpc-best-practices.

Flagship CernVM-FS repositories

Here we list a couple of flagship CernVM-FS repositories, all of which are publicly available.

LHC experiments

CernVM-FS repositories are used to distribute the software required to analyse the data produced by the Large Hadron Collider (LHC) at each of the LHC experiments.

Examples include (click to browse repository contents):

LCG Releases

The LCG Software Stacks which is distributed via the CernVM-FS repository /cvmfs/sft.cern.ch contains in total over 800 external packages as well as HEP-specific tools and generators.

Software installations included often come with a script that updates your shell environment for using them by sourcing it. In addition, through so-called views a complete software stack can be made available in your shell environment.

For example, loading software for the specific view LCG_107 for RHEL9 can be dona via: 

source /cvmfs/sft.cern.ch/lcg/views/LCG_107/x86_64-el9-gcc14-opt/setup.sh

The Alliance

The Digital Research Alliance of Canada, a.k.a. The Alliance and formerly known as Compute Canada, uses CernVM-FS to distribute the software stack for the Canadian national compute clusters.

Documentation on using their CernVM-FS repository /cvmfs/soft.computecanada.ca can be found here, and an overview of all available software can be found here.

Unpacked containers

CernVM-FS repositories can be used to provide an efficient way to access container images, by serving unpacked container images that can be consumed by container runtimes such as Apptainer.

Examples include:

More information on unpacked.cern.ch is available in the CernVM-FS documentation:

EESSI

The European Environment for Scientific Software Installations (EESSI) provides optimized installations of scientific software for x86_64 (Intel + AMD) and aarch64 (64-bit Arm) systems that work on any Linux distribution via the CernVM-FS repository /cvmfs/software.eessi.io.

We will use EESSI as an example CernVM-FS repository throughout this tutorial.

(next: What is EESSI?)