What Are RHEL Forks?
In the context of operating systems, especially in Unix or Linux, a fork is a system call that creates a new child process by duplicating the initiating parent process. The child process is distinct from the parent process solely in its Process ID (PID) and Parent Process ID (PPID), and it commences with resource utilizations set to zero. File locks and pending signals are not inherited.
Employing copy-on-write pages, Linux's fork implementation requires time and memory to duplicate the parent's page tables and develop a unique task structure for the child. This process aligns with the principles of containerization, which emphasize portability and resource efficiency, as seen in modern cloud-native applications.
RHEL forks represent Linux distributions originating from the source code of Red Hat Enterprise Linux (RHEL), a commercial, open-source Linux distribution developed by Red Hat, Inc. Encompassing the Linux kernel, additional software packages, support, and services, RHEL is tailored for enterprise environments. Utilizing RHEL's open-source components, community-driven projects have crafted various RHEL forks, each featuring unique modifications, functionalities, and package selections.
Key Features of RHEL Forks
Compatibility with RHEL packages and software
RHEL forks, such as CentOS, Rocky Linux, and AlmaLinux, maintain compatibility with RHEL packages and software. This compatibility enables users to easily transition between RHEL and its forks without significant modifications to their existing systems. Furthermore, it ensures that software developed for RHEL can run smoothly on RHEL forks, making them viable alternatives for businesses, developers, and individual users.
Open-source and free alternatives
RHEL forks are open source and free alternatives to the commercial RHEL distribution. This characteristic makes them attractive options for organizations and individuals seeking the stability and enterprise-grade features of RHEL without the associated costs and licensing requirements. The availability of RHEL forks as free alternatives allows a broader range of users to access the benefits of RHEL-based distributions without incurring financial burdens.
RHEL forks are typically community-driven projects, with developers and users from around the globe contributing to their development and enhancement. This collaborative approach allows the projects to benefit from diverse perspectives and expertise, resulting in more robust and versatile distributions. The community-driven nature of RHEL forks also fosters an open and transparent development process, where users can actively participate and influence the direction of the projects.
Stability and security
One of the primary objectives of RHEL forks is to provide stable and secure alternatives to RHEL. By building upon the RHEL source code, these forks inherit the stability and security features inherent in RHEL's enterprise-grade design. Developers of RHEL forks are committed to maintaining and improving these features, ensuring that users can confidently deploy them in production environments with the assurance of a reliable and secure platform.
Popular RHEL Forks
History and development
CentOS, short for Community Enterprise Operating System, was initially launched in 2004 as a free, open source RHEL fork. Over the years, it gained popularity among users who required a stable and enterprise-grade Linux distribution without the associated costs of a RHEL subscription. CentOS has traditionally followed RHEL releases closely, providing a binary-compatible alternative.
Shift to CentOS Stream
In December 2020, Red Hat announced the shift of CentOS from a stable RHEL clone to CentOS Stream, an upstream development branch that previews future RHEL releases. This change prompted concerns among CentOS users who relied on its stable nature for production environments, leading to the development of alternative RHEL forks.
Background and motivation
Rocky Linux was created in response to the CentOS shift, aiming to provide a free, open source, and community-driven RHEL alternative. Spearheaded by Gregory Kurtzer, the founder of CentOS, Rocky Linux seeks to fill the gap left by CentOS's transition to CentOS Stream by offering a stable and production-ready Linux distribution.
Features and compatibility
Rocky Linux maintains compatibility with RHEL packages and software, ensuring a smooth migration for users switching between RHEL and Rocky Linux. Rocky Linux benefits from diverse perspectives and expertise, resulting in a robust distribution. It is committed to providing a stable and secure platform for production environments.
Development by CloudLinux
AlmaLinux is another RHEL fork developed by CloudLinux, a company known for its commercial CloudLinux OS product. Launched in response to the CentOS shift, AlmaLinux aims to provide a stable, free, and open source alternative for users seeking a long-term support distribution.
Focus on stability and long-term support
With a focus on stability and long-term support, AlmaLinux is designed to cater to organizations and users who require a reliable and consistent platform for their production environments. AlmaLinux aims to offer regular updates and security patches, ensuring a secure and up-to-date distribution.
Oracle Linux is a RHEL fork developed and supported by Oracle Corporation. While it is available as a free, open source distribution, Oracle also offers commercial support and additional features for users who opt for a paid subscription.
Commercial support and optimization for Oracle software
Oracle Linux is specifically optimized for running Oracle software, making it an attractive choice for organizations using Oracle products. With commercial support available from Oracle, users can access enterprise-grade services and assistance, ensuring a reliable and well-supported platform for their production environments.
Migrating Between RHEL and RHEL Forks
Considerations and challenges
Compatibility: One of the primary considerations when migrating between RHEL and RHEL forks is ensuring compatibility with RHEL packages and software. Most RHEL forks maintain high levels of compatibility, but it is crucial to verify that the specific fork you choose aligns with your requirements.
Stability: The stability of the RHEL fork is another essential factor to evaluate. While some forks, like Rocky Linux and AlmaLinux, focus on providing a stable and production-ready environment, others may prioritize features or updates that could impact stability.
Support: Evaluate the level of support provided by the RHEL fork's community or vendor. The availability of documentation, forums, and dedicated support teams can significantly impact the ease of migration and ongoing management.
Licensing and costs: RHEL forks often provide a free, open source alternative to RHEL, but it is important to consider any licensing requirements or costs associated with commercial support or additional features.
Strategies and tools for migration
Backup and testing: Prior to migration, create a backup of your existing RHEL system and test the migration process in a non-production environment. This allows you to identify potential issues and refine the migration process without affecting your live environment.
Package compatibility: Analyze the compatibility of the installed packages on your RHEL system with the target RHEL fork. Identify any packages that may not be available or require modifications, and develop a plan to address these differences.
Configuration management: Utilize configuration management tools, such as Ansible, Puppet, or Chef, to automate the process of migrating configuration files, settings, and services between RHEL and RHEL forks. This can simplify the migration process and ensure consistency across environments.
Documentation and planning: Develop a detailed migration plan that outlines the steps, tools, and resources required for a successful migration. Refer to the official documentation and community resources for the specific RHEL fork to ensure that you follow best practices and recommended procedures.
Post-migration testing and validation: After migrating to the RHEL fork, thoroughly test the new environment to verify functionality, performance, and stability. This includes validating that applications, services, and configurations are working as expected, and that any customizations or modifications have been successfully applied.