Red Hat Enterprise Linux (RHEL)

Red Hat Enterprise Linux (RHEL) is a distribution of the Linux operating system developed for the business market. RHEL was formerly known as Red Hat Linux Advanced Server.

RHEL is based on free, open source code. Although Red Hat makes its source code available for download, verbatim copying of the distribution is forbidden.

The RHEL operating system (OS) supports diverse workloads in physical, virtualized and cloud environments. RHEL editions are available for servers, mainframe, SAP applications, desktops and OpenStack.

The RHEL 6.5 update, based on Linux kernel version 2.6.32-431, provides Precision Time Protocol (PTP) support, centralized certificate administration and security updates, large-scale resource management, broader support for solid-state storage devices and extended subscription management services. RHEL 7, which as this writing is still in beta, will have multiple file systems, supporting EXT4, XFS and btrfs in addition to EXT2 and EXT. The interface will also change, with Gnome 2 classic mode as the default.

Relationship with Fedora

Originally, Red Hat sold support for versions of Red Hat Linux (Red Hat Linux Enterprise Edition 6.2E was essentially a version of Red Hat Linux 6.2/7 with different support levels.) Starting with RHEL 2.1 AS in 2002, Red Hat sold their first version of RHEL. It was based on Red Hat Linux, but used a much more conservative release cycle. Later versions included technologies from the Red Hat–sponsored Fedora community distribution project. Red Hat Enterprise Linux release schedules do not follow that of Fedora (around 6 months per release) but are more conservative (2 years or more).

Fedora serves as upstream for future versions of RHEL. RHEL trees are forked off the Fedora repository, and released after a substantial stabilization and quality assurance effort. For example, RHEL 6 was forked from Fedora at the end of 2009 (approximately at the time of the Fedora 12 release) and released more or less together with Fedora 14. By the time RHEL 6 was released, many features from Fedora 13 and 14 had already been backported into it. The Fedora Project lists the following lineages for older Red Hat Enterprise releases:

  • Red Hat Linux 6.2/7 → Red Hat Linux Enterprise Edition 6.2E
  • Red Hat Linux 7.2 → Red Hat Enterprise Linux 2.1
  • Red Hat Linux 10 beta 1 → Red Hat Enterprise Linux 3
  • Fedora Core 3 → Red Hat Enterprise Linux 4
  • Fedora Core 6 → Red Hat Enterprise Linux 5
  • Fedora 12, 13 → Red Hat Enterprise Linux 6
  • Fedora 19, 20 → Red Hat Enterprise Linux 7

(Note about Fedora Core 1 and Red Hat Enterprise Linux 3: Red Hat released Red Hat Linux 10 beta 1, then took two forks from that codebase to seed both Fedora Core 1 and Red Hat Enterprise Linux 3 beta releases. There was some cross-pollination between the two up until shortly before the first production RHEL 3 release. Therefore, both FC1 and RHEL3 came from a common fork of RHL10beta1.)

RHEL 7

Red Hat Enterprise Linux 7 (Maipo) is based on Fedora 19, upstream Linux kernel 3.10, systemd 208, and GNOME 3.8 (rebased to GNOME 3.14 in RHEL 7.2). The first beta was announced on 11 December 2013,and a release candidate was made available on 15 April 2014.On June 10, 2014; 2 years ago Red Hat Enterprise Linux 7 was officially released.

  • Red Hat Enterprise Linux 7.0 (Maipo), June 10, 2014; 2 years ago, uses Linux kernel 3.10.0-123
    • 7.1, also termed Update 1, March 5, 2015; 2 years ago (kernel 3.10.0-229)
    • 7.2, also termed Update 2, November 19, 2015; 16 months ago (kernel 3.10.0-327)
    • 7.3, also termed Update 3, November 3, 2016; 4 months ago (kernel 3.10.0-514)