Red Hat Enterprise Linux
Encyclopedia
Red Hat Enterprise Linux (RHEL) is a Linux-based operating system
developed by Red Hat
and targeted toward the commercial
market. Red Hat Enterprise Linux is released in server versions for x86, x86-64, Itanium, PowerPC and IBM System z, and desktop versions for x86 and x86-64. All of Red Hat's official support and training and the Red Hat Certification Program
center around the Red Hat Enterprise Linux platform. Red Hat Enterprise Linux is often abbreviated to RHEL, although this is not an official designation.
The first version of Red Hat Enterprise Linux to bear the name originally came onto the market as "Red Hat Linux Advanced Server". In 2003 Red Hat rebranded Red Hat Linux Advanced Server to "Red Hat Enterprise Linux AS", and added two more variants, Red Hat Enterprise Linux ES and Red Hat Enterprise Linux WS.
While trademark
restrictions prevent free re-distribution of officially supported versions of Red Hat Enterprise Linux, compliance with open source licenses requires Red Hat to freely provide the source code for the distribution's software. As a result, several distributors have created re-branded and/or community-supported re-builds of Red Hat Enterprise Linux that can legally be made available, without official support from Red Hat.
It is often assumed the branding ES and AS stand for "Entry-level Server" and "Advanced Server", respectively. The reason for this is that the ES product is indeed the company's base enterprise
server product, while AS is the more advanced product. However, nowhere on its site or in its literature does Red Hat say what AS, ES and WS stand for.
In Red Hat Enterprise Linux 5 there are new editions that substitute former Red Hat Enterprise Linux AS/ES/WS/Desktop:
Red Hat had also announced its Red Hat Global Desktop Linux edition "for emerging markets
".
RHEL 3 and 4 and previous releases had four variants:
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:
In addition, the Fedora project includes Extra Packages for Enterprise Linux (EPEL), a community-provided set of packages for RHEL going beyond the ones that Red Hat selected for inclusion in its supported distribution.
“Both Fedora and Red Hat Enterprise Linux are open source. Fedora is a free distribution and community project and upstream for Red Hat Enterprise Linux. Fedora is a general purpose system that gives Red Hat and the rest of its contributor community the chance to innovate rapidly with new technologies. Red Hat Enterprise Linux is a commercial enterprise operating system and has its own set of test phases including alpha and beta releases which are separate and distinct from Fedora development.”
Since Red Hat Enterprise Linux is based completely on free
and open source
software, Red Hat makes available the complete source code to its enterprise distribution through its FTP site to anybody who wants it. Accordingly, several groups have taken this source code and compiled their own versions of Red Hat Enterprise Linux, typically with the only changes being the removal of any references to Red Hat's trademarks and pointing the update systems to non-Red Hat servers. Groups which have undertaken this include CentOS
(the 8th most popular as of November 2011), Oracle Linux, Scientific Linux
, White Box Enterprise Linux
, StartCom Enterprise Linux, Pie Box Enterprise Linux, X/OS, Lineox, and Bull
's XBAS for high-performance computing. All provide a free mechanism for applying updates without paying a service fee to the distributor.
Rebuilds of Red Hat Enterprise Linux are free but do not get any commercial support or consulting services from Red Hat and lack any software, hardware or security certifications. Also, the rebuilds do not get access to Red Hat services like Red Hat Network
.
Unusually, Red Hat took steps to obfuscate
their changes to the Linux kernel for 6.0 by not publicly providing the patch files for their changes in the source tarball, and only releasing the finished product in source form. Speculation suggested that the move was made in order to affect Oracle's competing rebuild and support services, which further modifies the distribution. This practice however, still complies with the GNU GPL since source code is defined as "[the] preferred form of the work for making modifications to it", and the distribution still complies with this definition. Red Hat's CTO Brian Stevens later confirmed the change, stating that certain information (such as patch information) would now only be provided to paying customers in order to make the Red Hat product more competitive against the growing number of companies offering support for products based on RHEL. CentOS developers had no objections to the change since they do not make any changes to the kernel beyond what is provided by Red Hat.
Server and Oracle Linux respin.
Note: A version outside of its Regular Life Cycle is normally unsupported, but support can still be obtained through Red Hat while the release is in its Extended Life Cycle through an add-on subscription, Extended Life Cycle Support.
Linux distribution
A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...
developed by Red Hat
Red Hat
Red Hat, Inc. is an S&P 500 company in the free and open source software sector, and a major Linux distribution vendor. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina with satellite offices worldwide....
and targeted toward the commercial
Business
A business is an organization engaged in the trade of goods, services, or both to consumers. Businesses are predominant in capitalist economies, where most of them are privately owned and administered to earn profit to increase the wealth of their owners. Businesses may also be not-for-profit...
market. Red Hat Enterprise Linux is released in server versions for x86, x86-64, Itanium, PowerPC and IBM System z, and desktop versions for x86 and x86-64. All of Red Hat's official support and training and the Red Hat Certification Program
Red Hat Certification Program
The Red Hat Certification Program is Red Hat's professional certification program for Red Hat and general Linux related skills such as system administration on Red Hat Enterprise Linux.All certifications are given after passing exams...
center around the Red Hat Enterprise Linux platform. Red Hat Enterprise Linux is often abbreviated to RHEL, although this is not an official designation.
The first version of Red Hat Enterprise Linux to bear the name originally came onto the market as "Red Hat Linux Advanced Server". In 2003 Red Hat rebranded Red Hat Linux Advanced Server to "Red Hat Enterprise Linux AS", and added two more variants, Red Hat Enterprise Linux ES and Red Hat Enterprise Linux WS.
While trademark
Trademark
A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...
restrictions prevent free re-distribution of officially supported versions of Red Hat Enterprise Linux, compliance with open source licenses requires Red Hat to freely provide the source code for the distribution's software. As a result, several distributors have created re-branded and/or community-supported re-builds of Red Hat Enterprise Linux that can legally be made available, without official support from Red Hat.
Variants
There are also "Academic" editions of the Desktop and Server variants. They are offered to schools and students, are less expensive, and are provided with Red Hat technical support as an optional extra. Web support based on number of customer contacts can be purchased separately.It is often assumed the branding ES and AS stand for "Entry-level Server" and "Advanced Server", respectively. The reason for this is that the ES product is indeed the company's base enterprise
Enterprise software
Enterprise software, also known as enterprise application software , is software used in organizations, such as in a business or government, contrary to software chosen by individuals...
server product, while AS is the more advanced product. However, nowhere on its site or in its literature does Red Hat say what AS, ES and WS stand for.
In Red Hat Enterprise Linux 5 there are new editions that substitute former Red Hat Enterprise Linux AS/ES/WS/Desktop:
- Red Hat Enterprise Linux Advanced Platform (former AS)
- Red Hat Enterprise Linux (former ES) (limited to 2 CPU-s)
- Red Hat Enterprise Linux Desktop with Workstation and Multi-OS option
- Red Hat Enterprise Linux Desktop with Workstation option (former WS)
- Red Hat Enterprise Linux Desktop with Multi-OS option
- Red Hat Enterprise Linux Desktop (former Desktop)
Red Hat had also announced its Red Hat Global Desktop Linux edition "for emerging markets
Emerging markets
Emerging markets are nations with social or business activity in the process of rapid growth and industrialization. Based on data from 2006, there are around 28 emerging markets in the world . The economies of China and India are considered to be the largest...
".
RHEL 3 and 4 and previous releases had four variants:
- Red Hat Enterprise Linux AS for mission-critical/enterprise computer systems.
- Red Hat Enterprise Linux ES for supported network servers
- Red Hat Enterprise Linux WS for technical power-userPower userA power user is a user of a personal computer who has the ability to use advanced features of programs which are beyond the abilities of "normal" users, but is not necessarily capable of programming and system administration...
enterprise desktops for high-performance computing - Red Hat Desktop for multiple deployments of single-user desktops for enterprises.
Relationship to free and community distributions
Originally, Red Hat sold support for versions of Red Hat Linux (Red Hat Linux 6.2E was essentially a version of Red Hat Linux 6.2 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
Red Hat Linux
Red Hat Linux, assembled by the company Red Hat, was a popular Linux based operating system until its discontinuation in 2004.Red Hat Linux 1.0 was released on November 3, 1994...
, but used a much more conservative release cycle. Later versions included technologies from the Red Hat sponsored Fedora
Fedora (operating system)
Fedora is a RPM-based, general purpose collection of software, including an operating system based on the Linux kernel, developed by the community-supported Fedora Project and sponsored by Red Hat...
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 → Red Hat Linux 6.2E
- Red Hat Linux 7.2 → Red Hat Enterprise Linux 2.1
- Red Hat Linux 9 → 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
In addition, the Fedora project includes Extra Packages for Enterprise Linux (EPEL), a community-provided set of packages for RHEL going beyond the ones that Red Hat selected for inclusion in its supported distribution.
“Both Fedora and Red Hat Enterprise Linux are open source. Fedora is a free distribution and community project and upstream for Red Hat Enterprise Linux. Fedora is a general purpose system that gives Red Hat and the rest of its contributor community the chance to innovate rapidly with new technologies. Red Hat Enterprise Linux is a commercial enterprise operating system and has its own set of test phases including alpha and beta releases which are separate and distinct from Fedora development.”
Rebuilds
Originally, Red Hat's enterprise product, then known as Red Hat Linux, was made freely available to anybody who wished to download it, while Red Hat made money from support. Red Hat then moved towards splitting its product line into Red Hat Enterprise Linux which was designed to be stable and with long-term support for enterprise users and 'Fedora' as the community distribution and project sponsored by Red Hat. The use of trademarks prevents verbatim copying of Red Hat Enterprise Linux.Since Red Hat Enterprise Linux is based completely on free
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
and open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
software, Red Hat makes available the complete source code to its enterprise distribution through its FTP site to anybody who wants it. Accordingly, several groups have taken this source code and compiled their own versions of Red Hat Enterprise Linux, typically with the only changes being the removal of any references to Red Hat's trademarks and pointing the update systems to non-Red Hat servers. Groups which have undertaken this include CentOS
CentOS
CentOS is a free operating system based on Red Hat Enterprise Linux . It exists to provide a free enterprise class computing platform and strives to maintain 100% binary compatibility with its upstream distribution...
(the 8th most popular as of November 2011), Oracle Linux, Scientific Linux
Scientific Linux
Scientific Linux is a Linux distribution produced by Fermi National Accelerator Laboratory and the European Organization for Nuclear Research...
, White Box Enterprise Linux
White Box Enterprise Linux
White Box Enterprise Linux was a free Linux distribution that was an alternative to Red Hat Enterprise Linux, primarily funded by the Beauregard Parish Library in Louisiana. White Box aimed to be 100% binary compatible with Red Hat Enterprise Linux....
, StartCom Enterprise Linux, Pie Box Enterprise Linux, X/OS, Lineox, and Bull
Groupe Bull
-External links:* * — Friends, co-workers and former employees of Bull and Honeywell* *...
's XBAS for high-performance computing. All provide a free mechanism for applying updates without paying a service fee to the distributor.
Rebuilds of Red Hat Enterprise Linux are free but do not get any commercial support or consulting services from Red Hat and lack any software, hardware or security certifications. Also, the rebuilds do not get access to Red Hat services like Red Hat Network
Red Hat Network
Red Hat Network is a family of systems management services operated by Red Hat that makes updates, patches, and bug fixes of packages included within Red Hat Linux and Red Hat Enterprise Linux available to subscribers...
.
Unusually, Red Hat took steps to obfuscate
Obfuscated code
Obfuscated code is source or machine code that has been made difficult to understand for humans. Programmers may deliberately obfuscate code to conceal its purpose or its logic to prevent tampering, deter reverse engineering, or as a puzzle or recreational challenge for someone reading the source...
their changes to the Linux kernel for 6.0 by not publicly providing the patch files for their changes in the source tarball, and only releasing the finished product in source form. Speculation suggested that the move was made in order to affect Oracle's competing rebuild and support services, which further modifies the distribution. This practice however, still complies with the GNU GPL since source code is defined as "[the] preferred form of the work for making modifications to it", and the distribution still complies with this definition. Red Hat's CTO Brian Stevens later confirmed the change, stating that certain information (such as patch information) would now only be provided to paying customers in order to make the Red Hat product more competitive against the growing number of companies offering support for products based on RHEL. CentOS developers had no objections to the change since they do not make any changes to the kernel beyond what is provided by Red Hat.
Commercial products based on Red Hat Enterprise Linux
A number of commercial vendors use Red Hat Enterprise Linux as a base for the operating system in their products. Two of the best known are the Console Operating System in VMware ESXVMware ESX
VMware ESX is an enterprise-level computer virtualization product offered by VMware, Inc. ESX is a component of VMware's larger offering, VMware Infrastructure, and adds management and reliability services to the core server product...
Server and Oracle Linux respin.
Version history
- Red Hat Enterprise Linux 2.1 AS (PensacolaPensacola, FloridaPensacola is the westernmost city in the Florida Panhandle and the county seat of Escambia County, Florida, United States of America. As of the 2000 census, the city had a total population of 56,255 and as of 2009, the estimated population was 53,752...
), 2002-03-26- Update 1, 2003-??-?? (Release Notes)
- Update 2, 2003-??-?? (Release Notes)
- Update 3, 2003-??-?? (Release Notes)
- Update 4, 2004-??-?? (Release Notes)
- Update 5, 2004-??-?? (Release Notes)
- Update 6, 2004-12-13 (Release Notes)
- Update 7, 2005-04-28 (Release Notes, redhat-release-as-2.1AS-121.src.rpm)
- Red Hat Enterprise Linux 2.1 ES (PanamaPanamaPanama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...
), May 2003
- Red Hat Enterprise Linux 3 (Taroon), 2003-10-22. Uses Linux 2.4.21 (Release notes also for updates)
- Update 1, 2004-01-16 (Release Notes)
- Update 2, 2004-05-18 (Release Notes)
- Update 3, 2004-09-03 (Release Notes)
- Update 4, 2004-12-21 (Release Notes)
- Update 5, 2005-05-20 (Release Notes)
- Update 6, 2005-09-28 (Release Notes)
- Update 7, 2006-03-15 (Release Notes)
- Update 8, 2006-07-20 (Release Notes)
- Update 9, 2007-06-15 (Release Notes)
- Red Hat Enterprise Linux 4 (Nahant), 2005-02-15. Uses Linux 2.6.9
- 4.1, also known as Update 1, 2005-06-09 (Release Notes)
- 4.2, also known as Update 2, 2005-10-05 (kernel 2.6.9-22, Release Notes)
- 4.3, also known as Update 3, 2006-03-07 (Release Notes) (Release Notes on centos.org)
- 4.4, also known as Update 4, 2006-08-11 (kernel 2.6.9-42, Release Notes)
- 4.5, also known as Update 5, 2007-05-01 (kernel 2.6.9-55, Release Notes)
- 4.6, also known as Update 6, 2007-11-15 (Release Notes)
- 4.7, also known as Update 7, 2008-07-24 (kernel 2.6.9-78, Release Notes)
- 4.8, also known as Update 8, 2009-05-18 (kernel 2.6.9-89, Release Notes)
- 4.9, also known as Update 9, 2011-02-16 (kernel 2.6.9-100, Release Notes)
- Red Hat Enterprise Linux 5 (TikangaTikanga MaoriThe Māori word tikanga has a wide range of meanings — culture, custom, ethic, etiquette, fashion, formality, lore, manner, meaning, mechanism, method, protocol, style....
), 2007-03-14. Uses Linux 2.6.18 (Release notes)- 5.1, also known as Update 1, 2007-11-07 (Release Notes)
- 5.2, also known as Update 2, 2008-05-21 (Release Notes, single file)
- 5.3, also known as Update 3, 2009-01-20 (kernel 2.6.18-128, Release Notes)
- 5.4, also known as Update 4, 2009-09-02 (kernel 2.6.18-164, Release Notes)
- 5.5, also known as Update 5, 2010-03-30 (kernel 2.6.18-194, Release Notes)
- 5.6, also known as Update 6, 2011-01-12 (kernel 2.6.18-238, Release Notes and Errata for release)
- 5.7, also known as Update 7, 2011-07-21 (kernel 2.6.18-274, Release Notes and Errata for release)
- Red Hat Enterprise Linux 6 (Santiago), 2010-11-10 Uses Linux 2.6.32 (Release Notes).
- 6.1 also known as Update 1, 2011-05-19 (Release Announcement)
Life Cycle Dates
The various Red Hat Linux versions share a multiphase life cycle that can span 10 years. Errata Support Policies| Version | Date of Release | End of Support Dates |
|---|---|---|
| Red Hat Enterprise Linux 2.1 | 2002-03-26 (AS) 2003-05-01 (ES) |
2009-05-31 |
| 2003-10-23 |
2006-07-20 (End of Production 1) 2007-06-30 (End of Production 2) 2010-10-31 (End of Production 3 / End of Regular Life Cycle) 2013-10-31 (End of Extended Life Cycle) |
|
| 2005-02-14 | 2009-03-31 (End of Production 1) 2011-03-31 (End of Production 2) 2012-02-29 (End of Production 3 / End of Regular Life Cycle) 2015-02-28 (End of Extended Life Cycle) |
|
| 2007-03-15 | Q4 2011 (End of Production 1) Q4 2012 (End of Production 2) 2014-03-31 (End of Production 3 / End of Regular Life Cycle) 2017-03-31 (End of Extended Life Cycle) |
|
| 2010-11-10 | Q4 2014 (End of Production 1) Q4 2015 (End of Production 2) 2017-11-30 (End of Production 3 / End of Regular Life Cycle) 2020-11-30 (End of Extended Life Cycle) |
|
| ? | ? |
Note: A version outside of its Regular Life Cycle is normally unsupported, but support can still be obtained through Red Hat while the release is in its Extended Life Cycle through an add-on subscription, Extended Life Cycle Support.