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With the 2020 decision to discontinue CentOS Linux, two new Enterprise Linux distributions have arrived to fill the void: AlmaLinux, supported by CloudLinux, and Rocky Linux, led by one of the creators of CentOS Linux, Gregory Kurtzer. Now with both distributions boasting several successful versions and both ready for use in enterprise deployments, comparing AlmaLinux and Rocky Linux is a useful exercise for teams considering their Enterprise Linux options.
In this blog, I provide an in-depth comparison of AlmaLinux and Rocky Linux in all aspects of the two distributions, including everything from community and sponsorship, to release delay and available business support providers.
Key differences between AlmaLinux and Rocky Linux
Since both AlmaLinux and Rocky Linux are downstream rebuilds of Red Hat Enterprise Linux, the differences are minimal. Both projects proudly state this on their websites, with Rocky Linux claiming they are " designed to be 100% bug-by-bug compatible with Red Hat Enterprise Linux "And AlmaLinux which states that they are" 1: 1 binary compatible with RHEL and CentOS pre-Stream . "
These stated goals should result in a very similar end-user experience, which means they are generally interchangeable with little effort. However, there are some differences behind the scenes and in public that can determine which distribution is best for a particular mission.
Community and sponsorship
The Rocky Enterprise Software Foundation (RESF) is a public utility company created by CentOS Linux co-founder Gregory Kurtzer " to organize a community around business, research, academia, individuals and other institutions ”Specifically for Rocky Linux. The RESF is made up of team leaders and other trusted individuals from within the Rocky Linux community with goals of transparency and mitigation of the possibility that an external individual or entity will take control of the project.
RESF invites sponsors and partners to contribute to Rocky Linux with a current balance of 12 sponsors , 12 partner e 2 support providers currently listed on the Rocky Linux website. The CIQ by Gregory Kurtzer is the founding sponsor, founding partner, and support partner for Rocky Linux.
AlmaLinux is provided by AlmaLinux OS Foundation , a 501 (c) (6) non-profit organization established to "(i) further develop and maintain AlmaLinux OS as a registration-free, ad-free, stable open source Linux distribution for the benefit of and free use by the public in general, (ii) facilitate and promote the growth of a community of suppliers and partners who provide solutions based on or complementary to the AlmaLinux operating system and (iii) undertake other activities that its Board of Directors may approve from time to time . The Foundation is made up of Contributing Members, Mirror Members, Sponsor Members and Alumnus Members.
The AlmaLinux website currently lists 21 supporters and 1 commercial support provider.
CloudLinux is the founding company of AlmaLinux, which provides $ 1 million in sponsorship annually, as well as the owner of TuxCare, the publicly traded support provider.
Popularity / adoption
None of the following numbers are indicative of a clear winner per se. As mentioned above, there are several reasons why one distribution or another might be best for a particular distribution.
Looking at the trend data from the past 12 months shows a good trend line in terms of popularity for distributions (based on page visits on distrowatch.com).
- 12 months ago, CentOS was in 29th place, with AlmaLinux and Rocky Linux in 31st and 35th respectively.
- 6 months ago, AlmaLinux had risen above CentOS in 25th place, with Rocky at 32 and CentOS at 33.
- 3 months ago, AlmaLinux peaked at 16, with Rocky Linux at 22 and CentOS at 37.
- Last month, Rocky Linux climbed to 15th place, with AlmaLinux dropping to 34 and CentOS dropping further to 40.
Cloud service provider market images
Let's take a look at the three biggest cloud providers: AWS, Azure, and Google Cloud. All three cloud service providers have official and third-party images available for both AlmaLinux and Rocky Linux.
On AWS, AlmaLinux and Rocky Linux both have official offers for AlmaLinux 8 and 9 for both x86_64 and arm64. There are around 365 total AlmaLinux offers and 401 total Rocky Linux offers, mostly from third party publishers.
On Azure, AlmaLinux has an official offer for AlmaLinux 8 and one for AlmaLinux HPC. Rocky Linux has an official image for Rocky Linux 8 on Azure. There are a total of 28 AlmaLinux offers and 27 total Rocky Linux offers, still mostly third party publishers.
Google Cloud lists one official AlmaLinux 8 and 9 product, two third-party AlmaLinux products, one official Rocky Linux 8 product, and three third-party products.
AlmaLinux and Rocky Linux offer on-premise images in their repositories.
AlmaLinux offers GenericCloud, GenericCloud-UEFI and OpenNebula images for AlmaLinux 8.6, as well as GenerciCloud and OpenNebula images for AlmaLinux 9.0.
Rocky Linux offers a GenericCloud image for Rocky Linux 8.6 and GenericCloud and EC2 images for Rocky Linux 9.0. Vagrant Cloud too Hashicorp has listings for both distributions!
The search for “AlmaLinux” returns seven pages of results with official AlmaLinux 8 and 9 boxes supporting hyperv, libvirt, parallels, virtualbox and vmware_desktop with a combined download count exceeding 14.000.
A search for "RockyLinux" returns six pages of results with the official Rocky Linux 9 boxes supporting libvirt and the official Rocky Linux 8 boxes supporting libvirt, virtualbox and vmware_desktop with a combined download count of around 7.000.
Torrent numbers are based on official torrent files posted on the mirrors of the respective distributions. Since x86 is the most popular architecture for AlmaLinux and Rocky Linux, I will focus on the number of seeds for x86-64 torrents only. (Numbers are as of August 3, 2022.)
Alma's torrent file contains all three ISO variants (boot, minimal, and DVD), while Rocky provides torrents for each of their ISO variants. Rocky dvd1 torrent is the most popular regardless of version, so I'll use that Rocky torrent for comparison.
AlmaLinux has a total of 362 seeds (an average of 120 seeds per torrent):
|AlmaLinux version||Number of seeds|
Rocky Linux has a total of 881 seeds (an average of 97 seeds per torrent):
|Rocky Linux version||Number of seeds|
Looking at EL9.0 alone, Alma has 139 seeds and Rocky has 287.
The seed number doesn't necessarily tell the whole story, as many torrent clients are only active while the end user downloads the necessary files.
So, let's take a look at the sharing ratio of my personal torrent client. I add the official torrent files to my personal torrent client as soon as possible after they are released to the public typically within an hour or so of posting, most certainly within 24 hours.
My sharing report for AlmaLinux is:
|AlmaLinux version||Sharing report|
|AlmaLinux-8.5-x86_64||4.584 (12,6GB / 57,6GB shared size)|
|AlmaLinux-8.6-x86_64||6.067 (12,6GB / 76,6GB shared size)|
|AlmaLinux-9.0-x86_64||5.028 (9,7GB / 48,6GB shared size)|
My share report for Rocky Linux is:
|Rocky Linux version||Sharing report|
|Rocky-8.5-x86_64-dvd1||6.337 (10,0GB / 63,3GB shared size)|
|Rocky-8.6-x86_64-dvd1||9.692 (10,4GB / 101,2GB shared size)|
|Rocky-9.0-x86_64-dvd1||5.157 (7,9GB / 40,6GB shared size)|
As we will see below in the Release Lag section, AlmaLinux has a track record of beating Rocky Linux to the GA version but, even considering that AlmaLinux versions have been available for several days, Rocky Linux seems to be downloaded (via torrent) other than AlmaLinux in all cases.
Official docker images for both distributions exceed 1 million downloads, so both have a strong presence despite only having docker images for only about a year.
Rocky Linux and AlmaLinux both have minor differences in how they develop their distributions, including differences in upstream source, build systems, and architecture support.
AlmaLinux, being a creation of CloudLinux, takes advantage of the company's existing CloudLinux “RHEL clone” as an immediate upstream.
Rocky Linux uses Red Hat's public git repository as an immediate upstream.
Does one have an advantage over the other? Not really, since CloudLinux supposedly uses Red Hat's public git repository as its immediate upstream.
AlmaLinux and Rocky Linux are both built using their own compilation systems.
AlmaLinux uses a AlmaLinux Build System (ALBS) customized to produce your own resources. I can't find any concrete information on when AlmaLinux started using this build system, or if they were using it from the start, but the first build on build.almalinux.com is from September 15th 2021, so I think I can assume with sure that AlmaLinux 8.6 and 9.0 were compiled with ALBS, but they could also have been earlier versions.
Prior to Rocky Linux 9.0, the Rocky Release Engineering team used Koji (and other Fedora components) to build Rocky Linux. Starting with Rocky Linux 9.0, the build system has been replaced with Peridot by Rocky. It was the build system change that caused a lot of the release delay for RL 9.0, which we'll talk about in a bit.
X86_64 support was the first platform released by both distributions and both now support aarch64, ppc64le, s390x and x86_64 with their 9.0 versions.
Starting with AlmaLinux 8.4, support for aarch64 has been added, AL 8.5 has added ppc64le and AL 9.0 has introduced support for s390x.
In contrast, Rocky Linux included support for aarch64 from the start but did not include support for ppc64le or s390x up to RL 9.0.
There are two types of release lag that I like to keep an eye out for, the initial release delay and the update release delay.
Initial release delay
The first is the initial release delay. Typically, this applies to major releases, but since both AlmaLinux and Rocky Linux joined RHEL's rebuild team midway through EL8.x, it also applies to minor releases.
AlmaLinux was the first of RHEL's rebuilds to receive a GA version with AlmaLinux 8.3 released on March 26, 2021.
|Release version||AlmaLinux release delay||Rocky Linux Release Delay|
|8.4||Orders shipped to Europe||Orders shipped to Europe|
|8.5||Orders shipped to Europe||Orders shipped to Europe|
|8.6||Orders shipped to Europe||Orders shipped to Europe|
|9.0||Orders shipped to Europe||Orders shipped to Europe|
As mentioned above, the entire Rocky Linux build system has been replaced with RL 9.0, which explains the higher release delay for RL 9.0. Now that Peridot is in production, it will be used to build all the Rocky Linux releases below (hopefully the release delay will decrease). The Rocky Linux Release Engineering Team has pledged to release the assets when they are tested and ready, because quality releases are more important than winning the "who released first" race.
Update the release delay
The second type of release delay is the release delay of updates. This is the delay between the time Red Hat publishes a package update and the time the RHEL rebuild distribution releases the package update.
With so many updates to consider, I'll just look at a couple of kernel updates to get an example of the expected release delay. The timestamps I am using for comparison are the dates of the files on my local mirror.
|Release version||Kernel update||AlmaLinux release delay||Rocky Linux release delay|
|kernel-4.18.0-305.3.1.el8_4.x86_64.rpm||1 days||Orders shipped to Europe|
|kernel-4.18.0-305.25.1.el8_4.x86_64.rpm||0 days||0 days|
|kernel-4.18.0-348.2.1.el8_5.x86_64.rpm||0 days||1 days|
|kernel-4.18.0-348.23.1.el8_5.x86_64.rpm||1 days||1 days|
|kernel-4.18.0-372.9.1.el8.x86_64.rpm||0 days||0 days|
|kernel-4.18.0-372.13.1.el8_6.x86_64.rpm||1 days||1 days|
As we can see, after version 8.4, the update release delay is now minimal for both distributions, with a typical delay of a day or less after Red Hat has released the update for RHEL.
Features included and functionality
The features included in both distributions should be the same. Looking at the repositories offered by each distribution, there are the same base repositories.
Where they differ is that Rocky Linux provides a "devel" repository that contains the packages needed for building other packages.
Otherwise, the package offerings for both AlmaLinux 8 and Rocky Linux 8 are nearly identical with both repositories containing around 6850 RPM. The same is seen with AL 9 and RL 9 with around 6330 RPM posted by both. Most of the changes are optional packages created from the same file spec or distribution specific packages.
Both AlmaLinux and Rocky Linux provide migration tools to assist with system conversion from another distribution.
Upgrading / migrating between major releases (7-> 8, 8-> 9, etc.) is complicated and not something to go in on a whim. Migration between distributions within a major release (RHEL8-> Rocky8, Oracle8-> Alma8, etc.), however, is fairly well documented and has a very successful history. If you are considering migrating between releases, Managed Server can assist you in determining best practices to use and can even develop custom procedures to ensure the successful migration of your mission-critical systems.
AlmaLinux provides the tool HIGH which claims to support “migration between major releases of RHEL derivatives. Easily upgrade from CentOS 7.x to any 8.x of your choice. "
We talked about it abundantly and in detail in this post: CentOS 8 End Of Life, let's update it to AlmaLinux
Rocky Linux provides the tool migrate2rocky . Rocky's utility is meant to migrate within a major version, providing different scripts for EL8 to Rocky8 or EL9 to Rocky9 migrations. migrate2rocky minimizes the number of variables it has to manage during the migration by requiring the EL8.x system to be upgraded to at least 8.5. The documentation includes commands to modify CentOS repositories so that CentOS <8.5 systems can update 8.5 before migration.
Business support and feasibility
Business profitability is strong with both options! Here at Managed Server, we look at several factors to determine if a deployment is “business ready”. The elements that the distribution must provide are:
- A rich number of packets, including a widely distributed mirror network
- Updates (major and / or minor versions of the operating system)
- Patching (package updates within a major / minor version)
There are two other necessary elements. These are not necessarily provided by the distribution itself and may be provided by one or more third parties:
- Support with an SLA
- Availability of professional services
AlmaLinux and Rocky Linux both provide all the elements of distribution and support from their parent companies.
By checking the last box on this Enterprise Linux checklist, professional services may be available from the parent companies, but third-party support and professional services are available. For example, Managed Server provides professional support and services for AlmaLinux, Rocky Linux, and many other Enterprise Linux distributions.
Other notable differences
Some Linux distributions have been deemed not ready for business use simply due to the lack of public mirrors that host the distribution's packages. If a distribution has only a very small handful of mirrors, the chance that the mirrors are unreachable (or unusually slow) is too high for mission critical systems to rely on.
Neither AlmaLinux nor Rocky Linux have to worry about this as they are both very widespread and adopted by most hosting providers on the market.
Final thoughts and conclusions
While the comparison of AlmaLinux and Rocky Linux is a useful exercise for teams considering their next Enterprise Linux distribution, at the end of the day both distributions are very similar. And, given the quality of the releases up to this point, companies can be successful with either option.
We personally in case of installation of a new distribution or update from an old CentOS distribution we always tend to prefer AlmaLinux for the simple fact that there is a company behind its development and support.