Red Hat Enterprise Linux

Red Hat Enterprise Linux

Red Hat Enterprise Linux 5's default GNOME desktop (Tikanga)
Company / developer	Red Hat, Inc.
OS family	Unix-like
Working state	Current
Source model	Open source
Initial release	March 31, 2003 (RHL discontinued) & stated as RHEL on March 26, 2002
Latest stable release	5.5 / March 30, 2010; 10 months ago (2010-03-30)
Latest unstable release	6 Beta 2 / June 30, 2010; 7 months ago (2010-06-30)
Marketing target	commercial market (include Mainframes, Servers, Supercomputers)
Available language(s)	Multilingual
Update method	Yum (PackageKit)
Package manager	RPM Package Manager
Supported platforms	x86, i386, x86-64, Itanium; PowerPC; s390, s390x
Kernel type	Monolithic (Linux)
Default user interface	GNOME
License	Various (mainly the GNU GPL for the Linux kernel and most included packages)
Official website	www.redhat.com/rhel/

Red Hat Enterprise Linux (RHEL) is a Linux distribution produced by Red Hat and targeted toward the commercial market, including mainframes. 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.^[1]

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.

Verbatim copying and redistribution of the entire Red Hat Enterprise Linux distribution is not permitted due to trademark restrictions.^[2] However, there are several redistributions of Red Hat Enterprise Linux—such as CentOS—with trademarked features (such as logos, and the Red Hat name) removed.

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 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:^[3][4]

• 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"^[5]. But as per a recent press release it has totally dropped the idea of its Global Desktop. "There won't be a consumer desktop from Red Hat as it's not going to be profitable".

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-user enterprise desktops for high-performance computing
• Red Hat Desktop for multiple deployments of single-user desktops for enterprises.

Relationship to free or 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.)^[6] 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 a testbed for software to be included in future versions of RHEL. There exists a popular opinion that RHEL releases are based on specific versions of Fedora, however there has never been any statement made by Red Hat to support the opinion, and the numbers given for relations often differ based on source of opinion.

“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.”^[7]

The Fedora Project does list the following lineage for Red Hat Enterprise releases:^[8]

• 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

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 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 most popular as of March 2009),^[9] Oracle Enterprise Linux, Scientific Linux, White Box Enterprise Linux, StartCom Enterprise Linux, Pie Box Enterprise Linux, X/OS, and Lineox. All with the exception of Oracle Enterprise Linux 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.

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 ESX Server and Oracle Enterprise Linux respin.

Version history

The various Red Hat Linux versions have little different Errata Support Policies

• Red Hat Linux 6.2E (Zoot), 27 March 2000
• Red Hat Enterprise Linux 2.1 AS (Pensacola), 2002-03-26^[10]
• Red Hat Enterprise Linux 2.1 ES (Panama), May 2003
• Red Hat Enterprise Linux 3 (Taroon), 22 October 2003. Uses Linux 2.4.21 (Release notes also for updates)
  • Update 1, 2004-01-16
  • Update 2, 2004-05-18
  • Update 3, 2004-09-03
  • Update 4, 2004-12-21
  • Update 5, 2005-05-20
  • Update 6, 2005-09-28
  • Update 7, 2006-03-15
  • Update 8, 2006-07-20
  • Update 9, 2007-06-15
• 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 (Release Notes)
  • 4.3, also known as Update 3, 2006-03-07 (Release Notes)
  • 4.4, also known as Update 4, 2006-08-11 (Release Notes)
  • 4.5, also known as Update 5, 2007-05-01 (Release Notes)
  • 4.6, also known as Update 6, 2007-11-15 (Release Notes)
  • 4.7, also known as Update 7, 2008-07-24 (Release Notes)
  • 4.8, also known as Update 8, 2009-05-18 (Release Notes)
• Red Hat Enterprise Linux 5 (Tikanga), 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 (Release Notes)
  • 5.4, also known as Update 4, 2009-09-02 (Release Notes)
  • 5.5, also known as Update 5, 2010-03-30 (Release Notes)
• Red Hat Enterprise Linux 6 (Santiago) not yet released, (Beta 1 released 2010-04-21,^[11] Beta 2 released 2010-06-30^[12]). Final version may be released before end of 2010.^[13]

See also

References

Further reading

• Jang, Michael H.. RHCE Red Hat Certified Engineer Linux Study Guide (RHEL 5). New York: McGraw-Hill. ISBN 978-0072264548. 
• Ghori, Asghar (2009). Red Hat Certified Technician & Engineer (RHEL 5). Reston: Global Village Publishing. ISBN 978-1615844302. 
• Fox, Tammy (2007). Red Hat Enterprise Linux 5 Administration Unleashed. Indianapolis, Ind.: Sams. ISBN 978-0672328923. OCLC 137291425. 
• McCarty, Bill (2004). Learning Red Hat Enterprise Linux and Fedora. Sebastopol, CA: O'Reilly. ISBN 978-0596005894. OCLC 55130915. 
• Negus, Christopher (2008). Fedora 9 and Red Hat Enterprise Linux Bible. Indianapolis, Ind.: Wiley. ISBN 978-0470373620. OCLC 222155845. 
• Sobell, Mark G. (2008). Practical Guide to Fedora and Red Hat Enterprise Linux. Upper Saddle River, NJ: Prentice Hall. ISBN 978-0137142958. OCLC 216616647. 
• Collings, Terry (2005). Red Hat Enterprise Linux 4 For Dummies. Hoboken, N.J.: Wiley. ISBN 978-0764577130. OCLC 58973830. 
• Petersen, Richard (2005). Red Hat Enterprise Linux & Fedora Core 4: The Complete Reference. London: McGraw-Hill. ISBN 978-0072261547. OCLC 62293551. 

External links

• Red Hat Enterprise Linux homepage
• Brian Stevens, CTO and vice president of engineering, Red Hat on why Red Hat Enterprise Linux is "The Business OS for Flexibility and Value"
• Red Hat Enterprise Linux at DistroWatch