The landscape of operating systems based on Red Hat Enterprise Linux (RHEL) is constantly evolving, marked by major updates and significant developments. Recently, we've seen a wave of updates from major players in the RHEL rebuild space, despite strategic moves from Red Hat that could affect their survival in the market.
On the same day that RHEL 9.3 and AlmaLinux 9.3 releases were announced, Oracle released Oracle Unbreakable Linux 9 update 3, followed closely by the Rocky Linux project with its 9.3 release.
For now, despite Red Hat's moves to shut them down, the world of RHELatives continues to spin, and while none of the companies' press releases mention it, it could be that these two releases owe something to the partnership of Oracle and Rocky in the new OpenELA alliance. The goal of CentOS Linux rebuilds has always been to be as close to a recompiled version of RHEL as possible, just with the serial numbers filed off and the names changed.
The added value that the rebuilders offered, beyond potentially saving a lot of money, was in their support communities, as well as additional tools over and above those provided by Red Hat.
For example, Oracle offers an optional kernel with Btrfs support, and AlmaLinux offers its ELevate tool that performs in-place upgrades from one major version to another – something that, surprisingly as it sounds to users of other distributions, was not a built-in feature of RHEL in the old days. Red Hat, as we noted earlier, lives on his small but very luxurious island in the Linux ocean, paying little attention to the fish nibbling at his toes.
Oracle Linux is notable for its limited compatibility with different CPU architectures and for its kernel with extra features, such as Btrfs support. Prior to the launch of version 9.3, Oracle unveiled its Linux-based Unbreakable Enterprise Kernel (UEK) 5.15, different from RHEL's 5.14, perhaps an attempt to distance itself from Red Hat's kernel sources. This release includes new drive authentication capabilities NVMe and SYN flood attack protection improvements.
Oracle primarily supports x86-64 and Arm64 architectures, excluding support for POWER and IBM mainframes found in RHEL, Alma, and Rocky. An interesting detail is that Oracle Linux for aarch64 ships exclusively with the UEK kernel.
Additionally, if your goal is to stay closely aligned with the RHEL version, the Red Hat 5.14 compatible kernel is also available. It should be noted that Oracle Linux 9.3 maintains its full binary compatibility with RHEL, consistent with its historical position, despite challenges arising from Red Hat's recent move to limit access to its source code .
Rocky Linux 9.3 offers unique features, such as support for cloud images and containers for the POWER architecture, and kernel packaging changes. The realtime build is now integrated into the main kernel package, and a new package offers Unified Kernel Images, introduced with systemd 252.
For now, Oracle and the new wave of CentOS rebuilds that followed Red Hat's demise of CentOS Linux appear to have successfully navigated the new restrictions Red Hat placed on the availability of its source code. If it follows the normal RHEL lifecycle, release 9 should last until version 9.10 in 2027, and we are sure that rebuilds will try to keep up with it but along with source code availability, end-of-life dates can change suddenly and unexpectedly. The future of RHELatives remains uncertain.