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Red Hat's replacement of CentOS with CentOS Stream has upset companies that depend on Linux as their server OS.
CentOS Stream is a rolling release OS, which means it isn't ideal from a reliability standpoint as it does not have a fixed update release schedule. However, shortly after Red Hat declared the discontinuation of CentOS, two similar distributions were announced: Rocky Linux and AlmaLinux. These two distributions have become popular among CentOS users.
Rocky Linux and AlmaLinux have similar use cases and support the same architectures. However, Rocky Linux is a 1-to-1 binary to RHEL while AlmaLinux is Application Binary Interface-compatible with RHEL. Both distributions also have a difference in funding. Compare these newer distributions to decide which OS is best for your company.
Plans to overcome the RHEL source limitation
IBM acquired Red Hat in 2019. In June 2023, Red Hat/IBM decided to make the source for RHEL private, which makes it a challenge for Rocky Linux and AlmaLinux to remain 1-to-1 compatible with RHEL. To this end, both distributions have taken different paths.
Rocky Linux's path
Gregory Kurtzer is the creator of CentOS and Rocky Linux. Starting with CentOS, Kurtzer's goal was to create a free Linux distribution that is 1-to-1 binary compatible with RHEL. He created Rocky Linux to pick up where CentOS left off.
Rocky Linux has opted to retain the 1-to-1 compatibility by way of public cloud instances and Universal Base Images that are based on RHEL.
AlmaLinux is the product of CloudLinux. AlmaLinux is community-driven and focused primarily as an enterprise-grade Linux distribution. Like Rocky Linux, the goal of AlmaLinux is to remain 1-to-1 binary compatible with RHEL.
However, AlmaLinux has opted to drop its goal to remain 1-to-1 binary compatible with RHEL. Instead, AlmaLinux's new goal is to be Application Binary Interface-compatible with RHEL. To accomplish this, AlmaLinux plans to use CentOS Stream source code that Red Hat continues to make available.
The similarities between Rocky Linux and AlmaLinux
On the surface, Rocky Linux and AlmaLinux are similar. Their lifecycle is 10 years, they're targeted as production-grade, enterprise OSes, support is around eight years for each and updates are regular -- with a one-business-day lag from RHEL.
Both distributions use the Red-hat Package Manager and Dandified Yum package manager. Managing applications in Rocky Linux or AlmaLinux is similar to RHEL. These distributions also use firewalld, iptables and SELinux as their primary security mechanisms.
Another similarity is that Rocky Linux and AlmaLinux support the same architectures: x86_ 64, aarch64, ppc64le and s390x.
Both distributions include the following repositories, enabled by default:
- BaseOS: The core set of software packages for functionality.
- AppStream: Additional user space applications, runtime languages and databases.
- Extras: Packages that are not available in RHEL.
For installations with a GUI, Rocky Linux and AlmaLinux default to the GNU Network Object Model Environment.
AlmaLinux and Rocky Linux share similar uses. Both work for enterprise-grade servers, such as web and database servers. They are also similar to container and cloud deployments. Rocky Linux and AlmaLinux are suited to take on any use case RHEL would be used for.
The key differences between Rocky Linux and AlmaLinux
The differences between Rocky Linux and AlmaLinux aren't easy to spot, which is a product of both distributions being based on RHEL.
One difference is found within the realm of security. Although both include Secure Boot, SELinux and many similar advanced features in RHEL, AlmaLinux adds a focus on the Center for Internet Security Benchmark.
Beyond that, funding is different for each distribution and could be the deciding factor for a company to choose one over the other.
AlmaLinux is driven by a nonprofit. CloudLinux and other sponsors, like WebPros and Black Host, grant AlmaLinux a $1 million annual sponsorship to guarantee the distribution will continue and always be free. Cloud Linux has been around since 2009. This set amount of funding per year and longevity of CloudLinux assures users that AlmaLinux will always have funding for updates.
Rocky Linux is community driven. In 2022, Ctrl IQ (CIQ), the founding sponsor and service provider of Rocky Linux, gave $26 million in funds to the distribution. This is a one-time fund to Rocky Linux, which means more funds are needed in the future. CIQ was founded in 2020. Rocky Linux prospects might be deterred from the distribution if they do not want to take a chance with a newer company sponsoring Rocky Linux.
However, that is not to discount Rocky Linux. CIQ might be a newcomer, but they have grown fast and have an outstanding reputation within the world of technology. Kurtzer has a massive built-in fan base because of CentOS, so the Rocky Linux community should continue to grow. With Kurtzer's dedication to improving what he did with CentOS, users can be certain he is committed to the community.
According to Google Trends, AlmaLinux has been the more popular choice since around July 2020. The trend continues as AlmaLinux sees more interest over time and a larger subregion breakdown within the United States. And if you compare the two on a worldwide scale, the difference is even more dramatic. However, if you look at another metric report -- which focuses on actual usage -- you'll see a much more accurate listing of how each RHEL-based OS trends.
Whichever you pick, AlmaLinux and Rocky Linux will serve as proper replacements for CentOS or RHEL. If you are unsure, then download both, install them and see which one fits your needs the best.
Jack Wallen is an award-winning writer and avid promoter/user of the Linux OS.