The Tri-Lab Operating System Stack (TOSS) was initially created to run on LC HPC systems. The goal of the TOSS project has been to increase efficiencies in the ASC Tri-Lab community with respect to both the utility and the cost of a common computing environment. The project delivers a fully functional cluster operating system, based on Red Hat Linux, capable of running MPI jobs at scale on hardware across the Tri-Lab complex. Today, practically all LLNL Livermore Computing systems run TOSS.

As time as passed and the project has evolved, more HPC sites have begun using TOSS, including NASA as their main OS for their NAS Clusters.

Compliance Baseline

The TOSS team partnered with DISA (Defense Information Systems Agency) to create a STIG (Security Technical Implementation Guide) see the official DISA announcement for more details. The guide itself can be found and downloaded at:

Supported Versions

As TOSS is built on RedHat Enterprise Linux, the versions (and support) tend to be directly related to the release and support of the "upstream" RHEL versions.

TOSS Supported Versions
TOSS Version Upstream RHEL Version Release Date End of Support
3.7-x 7.9 October 2020 June 2024
4.5-x 8.7 November 2022 May 2023
4.6-x 8.8 June 2023 December 2023


Below are selected references for more information about TOSS:

Citing / Referencing TOSS

To reference TOSS, please cite the following paper: 

Edgar A. León, Trent D’Hooge, Nathan Hanford, Ian Karlin, Ramesh Pankajakshan, Jim Foraker, Chris Chambreau, and Matthew L. Leininger. TOSS-2020: A Commodity Software Stack for HPC. In International Conference for High Performance Computing, Networking, Storage and Analysis, SC’20. IEEE Computer Society, November 2020.