Operating systems
The operating system (OS) dictates how system admins and users interact with the computational hardware of the lab. They come with different purposes, design decisions, and ecosystems for high-performance computing. Since November of 2017, 100% of supercomputers use linux and we are no different. RedHat Enterprise Linux (RHEL) is by far the most popular operating system, followed by Ubuntu and Cray.
| Operating System | Percentage (%) 1 |
|---|---|
| RHEL | 20.0 |
| Ubuntu | 11.8 |
| Cray | 9.8 |
| CentOS 2 | 8.2 |
| Rocky | 5.8 |
Cost
tl;dr: RHEL is not free for any scale. Ubuntu is free with an optional paid subscription for additional support (i.e., no feature locks).
Cost is always the first factor I consider when choosing an OS. RHEL is free for up to 16 nodes through its RedHat Developer program. Its use is limited to development, testing, and small production uses spanning personal servers, home labs, and small open-source communities. In other words, not small organizations or teams.
Ubuntu, both server and desktop, are completely free with the optional paid subscription of Ubuntu Pro. This service primarily provides additional security maintenance, dedicated support, and easier system management.
Decision
Given that academic labs often run on tight budges, we are recommending Ubuntu. Next, we will discuss near automated setup of our Ubuntu operating system.
Operating system distributions for world’s supercomputers are from the June 2025 TOP500 release. ↩︎
CentOS has been replaced with CentOS Stream that is an upstream repository of RedHat. ↩︎