OpenHPC on Rocky Linux: Painless HPC cluster management

OpenHPC has quietly become the Swiss Army knife of HPC deployments - but substitute tiny scissors and a toothpick for a complete stack of pre-integrated scientific computing tools that actually work together. If you've ever spent three weeks trying to get the Fastest Fourier Transform in the West (FFTW) to compile properly with your specific compiler-MPI combination only to discover you need a different Portable, Extensible Toolkit for Scientific Computation (PETSc) version, OpenHPC might just be your salvation.

OpenHPC provides a collaborative, Linux Foundation-backed ecosystem that transforms the traditionally painful process of HPC cluster deployment into a seamless experience approaching sanity. It provides a compelling alternative to expensive commercial solutions, especially for organizations seeking enterprise-grade stability without the licensing headaches.

This series explores OpenHPC's architecture, practical deployment on Rocky Linux systems, real-world use cases, and the challenges that keep HPC administrators awake at night - all while revealing how modern cluster management approaches are transforming HPC operations into an engineering discipline.

OpenHPC under the hood (or bonnet)

OpenHPC operates on a simple premise: why should every HPC site waste months compiling the same software stack when we could build it once, test it thoroughly, and distribute pre-built packages? The reality, of course, is more nuanced.

At its core, OpenHPC employs a hierarchical software architecture built around compiler-MPI family combinations. Everything lives under /opt/ohpc/, organized into a logical structure that would make a librarian weep with joy. The magic happens through Lmod's hierarchical module system, which automatically manages complex dependency chains. Load a GNU9 compiler module and suddenly MPI implementations become visible. Load OpenMPI on top of that, and libraries built specifically for that GNU9-OpenMPI combination appear automagically.

The package naming convention tells the whole story: petsc-gnu9-mvapich2-ohpc gives you PETSc built with GNU9 compilers and MVAPICH2, while boost-gnu9-ohpc provides Boost for any MPI with GNU9. This systematic approach eliminates the classic HPC administrator nightmare of accidentally mixing incompatible library builds.

OpenHPC's value proposition becomes super clear when compared to alternatives like EasyBuild or Spack. While EasyBuild offers ultimate flexibility through source-based builds and Spack provides sophisticated dependency resolution, OpenHPC prioritizes deployment speed and operational simplicity. You trade some customization for the confidence that comes with community-validated software combinations that thousands of other sites are successfully running.

The project includes over 350 packages across development tools, scientific libraries, performance analysis tools, and resource managers. Everything from high-performance scientific software libraries (such as FFTW and PETSc) to performance analysis tools (such as TAU and Scalasca) comes pre-built, tested, and integrated through continuous integration systems that validate bare-metal installations.

Understanding OpenHPC's Component Categories

OpenHPC organizes its packages into functional groupings. Each category provides:

Administrative Tools manage cluster operations. For example, tools like parallel distributed shell (pdsh), (Node Health Check (nhc), and so on.

Compiler Families transform source code into executable programs. OpenHPC includes GNU (gcc), Intel, and Arm compilers, each optimized for different hardware architectures. Your choice affects application performance significantly.

Development Tools streamline software building and installation. EasyBuild and Spack automate complex dependency chains, while Valgrind debugs memory issues. These tools make managing scientific software stacks manageable instead of maddening.

IO Libraries handle scientific data storage and retrieval. HDF5 and NetCDF provide efficient formats for storing massive simulation datasets, while parallel versions (pHDF5, pnetcdf) let hundreds of nodes write data simultaneously without corruption.

MPI Runtime/Transport Families enable parallel computing - the heart of HPC. MPI (Message Passing Interface) lets programs running on different compute nodes communicate and coordinate. OpenHPC provides multiple MPI implementations (OpenMPI, MPICH, MVAPICH2) and transport layers (libfabric, UCX) optimized for different network hardware. Think of MPI as the postal service that lets your parallel programs exchange messages across the cluster.

Parallel Libraries provide pre-built mathematical and scientific algorithms optimized for distributed computing. PETSc solves differential equations across thousands of cores, while ScaLAPACK performs linear algebra on matrices too large for single machines. These libraries represent decades of optimization work and should be considered instead of reimplementing algorithms.

Performance Tools diagnose bottlenecks and optimize code. TAU profiles where your application spends time, Scalasca identifies communication inefficiencies, and PAPI provides low-level hardware performance counters.

Provisioning/Resource Management orchestrates cluster operations. Warewulf deploys operating systems to compute nodes, while Slurm schedules jobs and allocates resources. These systems ensure users can share cluster resources fairly and efficiently.

Runtimes provide containerization and application isolation. They allow researchers to package applications with all dependencies included.

Understanding these categories helps you navigate OpenHPC's ecosystem and select the right tools for your workloads. See the complete component list here.

Rocky Linux reality check: navigating the version maze

Here's where things get interesting - and slightly frustrating. Rocky Linux 10 dropped in June 2025, but OpenHPC hasn't caught up yet. The current OpenHPC 3.x series fully supports Rocky Linux 8 & 9, while Rocky Linux 10 support awaits the eventual OpenHPC 4.x release that will target Enterprise Linux (EL) 10-based builds.

This timing mismatch isn't necessarily a problem. Rocky Linux 9 remains an excellent choice for HPC deployments, offering a 10-year support lifecycle (until May 2032) and proven stability in production environments. So much so that major HPC sites like the University of Stuttgart's Hawk supercomputer (26 PFLOPS) run Rocky Linux successfully, demonstrating its enterprise readiness.

The Rocky Linux advantage for HPC centers is compelling:

• Bug-for-bug EL compatibility without licensing fees for compute nodes
• Backing of the Rocky Enterprise Software Foundation (RESF)
• Independent project leadership and strong community support
• Governance by HPC pioneers like Gregory Kurtzer (Warewulf founder and CentOS O.G.)

And if you want or need it, support and professional services are always available from CIQ - backed by real codEE (yes, that’s intentional - ask us to unlock your easter egg).

At scale, with hundreds or thousands of compute nodes - the savings become substantial.

!!! Tip Rocky Linux 10's requirement for x86-64-v3 microarchitecture (roughly Intel Haswell 2013+) might actually benefit HPC environments by ensuring minimum performance baselines, though it could complicate deployments on older hardware. The removal of 32-bit support and mandatory NetworkManager represents a cleaner, more modern foundation for HPC clusters.

Practical deployment on Rocky Linux 9 follows OpenHPC's standard recipe format: install the ohpc-release RPM, enable EPEL repositories, install ohpc-base components, choose your provisioning system (Warewulf remains the most popular), select your resource manager (Slurm dominates with ~60% adoption), and create compute node images. The process is well-documented but requires careful attention to network configuration details - something we'll explore in depth throughout this series.

The deployment journey: two paths, one destination

OpenHPC deployment follows a structured four-phase process:

Phase 1 establishes the System Management Server (SMS) foundation - install Rocky Linux, configure repositories, and set up basic services. Phase 2 configures the SMS with OpenHPC components, provisioning systems, and resource managers. Phase 3 creates compute node images through either traditional chroot environments or modern container-based approaches. Phase 4 integrates everything into a functioning cluster with job schedulers and storage systems.

The critical decision points happen early. Warewulf versus xCAT for provisioning - Warewulf wins for simplicity and stateless deployments, while xCAT offers more flexibility for complex heterogeneous environments. Slurm versus PBS Professional for resource management - Slurm dominates in academic environments with its active open-source development, while PBS Professional provides commercial-grade features for enterprises requiring vendor support.

Network architecture decisions have long-term consequences. Single head node configurations work for smaller clusters, but distributed management becomes necessary as you scale. The network fabric choices - 1GbE for management, high-speed InfiniBand or Omni-Path for compute, separate BMC networks for hardware management - require careful planning and can't easily be changed after the fact.

But here's what makes this series different from traditional OpenHPC tutorials: we're going to show you two fundamentally different approaches to relevant phases of deployment. You'll see the traditional, manual method that's extensively documented in OpenHPC installation guides and running on thousands of production clusters worldwide. Then you'll see how modern cluster orchestration tools transform the same tasks from multi-hour manual processes into automated, repeatable procedures. You’ll also see the full spectrum of possibilities and be able to make informed decisions about where you invest your time and resources.

Real-world impact: where OpenHPC shines

OpenHPC excels in research computing environments where diverse scientific applications need consistent software foundations. Computational chemistry groups modeling polymer behavior, bioinformatics teams analyzing genomic data, and physics researchers running climate simulations all benefit from OpenHPC's pre-integrated scientific libraries and hierarchical module system.

Academic multi-tenant environments represent OpenHPC's sweet spot. Universities with multiple research groups sharing computing resources appreciate the standardized software stacks that reduce support overhead while providing users flexibility to select appropriate compiler-MPI combinations. The environment module system allows users to experiment with different toolchains without administrator intervention.

Production deployments reveal OpenHPC's cluster management capabilities shine in specific scenarios. Node provisioning through Warewulf's stateless approach simplifies maintenance and ensures configuration consistency. Configuration management through template-based systems and file synchronization reduces operational overhead. Orchestration capabilities coordinate complex service startup sequences and dependency management.

We'll address real-world challenges head-on throughout this series rather than glossing over them. Network configuration issues dominate community support requests. Hardware compatibility presents ongoing challenges. The hierarchical module system, while powerful, adds complexity that newer HPC administrators find daunting. Configuration complexity scales poorly - what works for 10-node clusters becomes unwieldy at 100+ nodes.

These are some of the reasons to approach your OpenHPC deployment with your eyes open and to consider how modern tooling can mitigate these traditional pain points.

Series roadmap: your guided tour

Over the next six posts (seven if you count the two-part SMS foundation deep-dive), we're going to walk through every phase of OpenHPC deployment with both traditional and modern approaches. You'll see the actual commands, real configuration files, and honest assessments of what works, what breaks, and why.

Post 1: OpenHPC on Rocky Linux: Painless HPC Cluster Management Posts 2a & 2b: SMS Foundation - Your Cluster's Command Center Post 3: Image Engineering - Building Your Compute Node Operating Systems Post 4: Production Deployment - From Empty Racks to Running Jobs Post 5: Real-World Operations - Keeping Your Cluster Alive Post 6: The Next Generation - Beyond Traditional Clusters

Your starting point

Whether you're deploying your first cluster or your fiftieth, whether you're managing 10 nodes or 10,000, you need to understand what you're actually building. OpenHPC provides the software foundation. Rocky Linux provides the stable operating system platform. The deployment methods you choose determine whether building your cluster is a weeks-long ordeal or a days-long project.

Ready to begin? In Posts 2a and 2b, we'll start with the System Management Server - the brain of your cluster. You'll see exactly how to configure it the traditional way, then discover how modern approaches transform that experience. By the end of those two posts, you'll have a functioning SMS and a clear understanding of why the HPC community is rapidly adopting next-generation cluster management tools.

This is Part 1 of a 7-part series (published as 6 posts) on deploying OpenHPC clusters with Rocky Linux. Subscribe to our newsletter to get updates on the next posts!