Oracle Linux: Versions, Support Tiers & vs RHEL

This is a working reference on Oracle Linux — the same material our Linux server support team uses when assessing Oracle Linux estates. It covers what the distribution is, current versions and lifecycle dates, the two kernel options, what is free versus what requires a paid subscription, the support tiers, and how Oracle Linux differs from Red Hat Enterprise Linux.

What is Oracle Linux

Oracle Linux is an enterprise Linux distribution built from Red Hat Enterprise Linux source code and maintained by Oracle. It is binary-compatible with the corresponding RHEL release: applications certified for RHEL 9 run unmodified on Oracle Linux 9. Oracle has shipped it since 2006, and it is the operating system underneath Oracle Cloud Infrastructure, Oracle Exadata, and Oracle's own engineered systems.

The licensing model is the main structural difference from RHEL. Per the terms published on oracle.com/linux, Oracle Linux is free to download, use, and distribute — in development, test, and production — with no login, no subscription, and no per-system entitlement tracking. Installation media come from the Oracle Linux ISO page, and all binary updates and security errata are published on the public Oracle Linux yum server. Paying Oracle is a decision about support, not about the right to run the software.

Versions and lifecycle

Oracle Linux releases track RHEL major versions and follow Oracle's Lifetime Support Policy: ten years of Premier Support from general availability, with Extended Support available for a further window after that. The authoritative dates are in Oracle's Lifetime Support Policy for open source offerings (PDF) and the Oracle Linux product life cycle documentation.

Oracle Linux 7 is past Premier Support; systems still on it need an Extended Support contract for continued errata or a migration plan to 8 or 9. One lifecycle detail differs from RHEL: within a major version, only the newest minor release is current — once 9.6 ships, 9.5 stops receiving updates. RHEL, by contrast, sells Extended Update Support for staying on selected minor releases.

Two kernels: UEK and RHCK

Every Oracle Linux installation includes two interchangeable kernels, selectable at boot:

• UEK (Unbreakable Enterprise Kernel) — Oracle's own kernel build, based on a newer upstream Linux kernel than the RHEL-compatible one. It is the default on new installs, carries newer hardware and filesystem support (including Btrfs, which RHEL dropped), and is the kernel Oracle tests its database and engineered systems against. Documentation for each UEK release is on docs.oracle.com/en/operating-systems/uek.
• RHCK (Red Hat Compatible Kernel) — a kernel built from the same source version as the corresponding RHEL release. Workloads that require exact RHEL kernel behavior, or third-party kernel modules certified only against the RHEL kernel version, run on RHCK.

Both kernels are supported, both receive errata on the public yum server, and switching between them is a matter of installing the other kernel package and changing the default boot entry. User space is identical either way.

Free vs. paid: what a support contract adds

The free tier is unusually complete for an enterprise distribution: the full OS, all security errata and bug-fix updates from yum.oracle.com, both kernels, and no time limit or system cap. What a paid subscription adds is access to Oracle's support organization plus a set of paid-only technologies. The tiers, as listed on the Oracle Linux support page and priced in the Oracle Linux global price list (PDF):

Ksplice: the Premier-tier differentiator

Ksplice applies kernel and key user-space security patches to a running system without a reboot and without interrupting workloads. Oracle acquired the technology in 2011 and ships it as part of Premier Support; it works with both UEK and RHCK. For estates with strict uptime requirements — database hosts, telecom, trading — zero-downtime patching is the concrete feature that justifies Premier over Basic. Details are on the Oracle Ksplice page. RHEL's equivalent, kpatch, covers a narrower set of selected critical kernel fixes.

Oracle Linux vs. RHEL

The distributions share a code base, so the comparison is about source relationship, cost model, and options rather than day-to-day administration. A fuller profile of the Red Hat side is in our Red Hat Enterprise Linux reference.

Where Oracle Linux fits

• Oracle Database and middleware shops. Oracle certifies and tests its database against Oracle Linux with UEK first, and a single vendor covers both OS and database support tickets.
• Cost-driven RHEL exits. Organizations that want RHEL compatibility without per-system subscription spend can run Oracle Linux free and buy support only for the systems that need it — a mixed estate where production carries contracts and dev/test runs free is a common pattern.
• Former CentOS estates. After CentOS Linux 8 ended in 2021, Oracle Linux became one of the direct drop-in destinations alongside AlmaLinux and Rocky Linux, with the distinction that a paid support path from the OS vendor exists if needed later.
• OCI workloads. Oracle Linux images on Oracle Cloud Infrastructure include support at no additional cost.

Migrating from CentOS or RHEL

Oracle publishes a switch script — historically centos2ol.sh, now maintained as migrate-to-oracle-linux.sh — in the oracle/centos2ol GitHub repository. It repoints an existing CentOS, RHEL, Rocky, or AlmaLinux system of the same major version at Oracle Linux repositories, swaps the branding and release packages, and installs the Oracle kernel; the machine keeps its data, applications, and configuration. The repository notes the scripts are a community effort and not formally supported by Oracle, so the standard precautions apply: full backup or snapshot first, test on a clone, migrate one host before a fleet. What paid support looks like after the switch — and what we handle under contract — is covered in our Oracle Linux support overview.

FAQ

Is Oracle Linux really free?

Yes. The OS, all security errata, and bug-fix updates are free from yum.oracle.com for any number of systems, in production included. Payment is only for support contracts and the paid-only features they carry (Ksplice, Oracle Linux Manager, and similar).

Is Oracle Linux the same as RHEL?

It is built from RHEL source and is binary-compatible, so RHEL-certified applications run on it. It differs in the default kernel (UEK), the cost model (free OS, optional support), and minor-release policy (latest minor only).

Should I run UEK or the Red Hat Compatible Kernel?

UEK is the default and what Oracle products are tested against; it has a newer upstream base and Btrfs support. Choose RHCK when a third-party kernel module or a certification requires the exact RHEL kernel version. Both are supported and switchable at boot.

How long is an Oracle Linux release supported?

Ten years of Premier Support from GA, plus an Extended Support window. Oracle Linux 8 runs to July 2029, Oracle Linux 9 to June 2032; Oracle Linux 7 exited Premier Support at the end of 2024 and is in Extended Support until June 2028.