An overview of current and past versions of Red Hat Enterprise Linux Server

Each new version of Red Hat® Enterprise Linux® rolls out new features and capabilities. We provide support and maintenance over stated time periods—the lifecycle—for the major versions (3, 4, 5, or 6). The lifecycle lets you effectively plan, deploy, and support Red Hat Enterprise Linux.


For those organizations that want to stay on a particular snapshot or release for an extended period of time, Red Hat offers a choice of Add-Ons to give enterprise customers additional flexibility.

Version 6

Efficiency, scalability, and reliability

Optimized on highly scalable, multicore systems, Red Hat Enterprise Linux manages the underlying system complexity and reduces data bottlenecks so applications can perform their best.

Red Hat works closely with hardware partners and industry standard groups to enable the latest hardware functionality as it becomes available. Red Hat Enterprise Linux 6 provides operating system control for platforms to have enhanced system power management and end-to-end data integrity.

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Unprecedented resource management

Administrators and application developers can set policies by process, applications, and even guests to match network, memory, and CPU usage to business needs and service-level agreements (SLAs).

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Designed-in security


As a host, a guest, or in the cloud, applications can be secured with a common and comprehensive suite of technologies and policies backed by Red Hat's global Security Response Team.

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Stability and enterprise manageability

Stable application development and production platform

Develop and deploy with confidence knowing that all the packages shipped with Red Hat Enterprise Linux are supported and maintained.

In addition to the LAMP stack, the application development portfolio includes scripting languages like:

  • PHP
  • The TurboGears2 framework
  • The Eclipse IDE
  • Debugging/Tuning tools

Not only is deployment easy, but architects can use advanced caching technologies to scale as needed without additional complexity.

Red Hat Enterprise Linux provides comprehensive application support across cloud services, middleware, web applications, and enterprise applications.

Enterprise manageability

Red Hat provides 2 categories of control for datacenter operations. Our Smart Management Add-On and Red Hat Network Satellite servers centralize and automate common management functions so datacenters can scale systems without burdening staff.

Red Hat also packages the platform in system administer-friendly packages that let you tailor installations to application needs.

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Integrated virtualization

Red Hat Enterprise Linux is designed to be both a superior virtualization host and guest on any of the major hypervisors. With virtualization incorporated into the kernel, the complete breadth of system management, security tools, and certifications are available for your administrators to use.

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Version 5


All Red Hat Enterprise Linux Server products provide virtualization, and it's optionally available for desktop products.

  • Storage and extended server virtualization support either paravirtualized (Xen) or fully virtualized (KVM) guests.
  • Red Hat Network supports virtualized guest operating systems.
  • Virt-manager and libvirt/virsh management tools are available for single-system or scripted virtualization management.
  • Integration with Red Hat Enterprise Virtualization is available for enterprise virtualization management.

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Kernel, performance, and management

Kernel and performance

  • Continued hardware support for maximum flexibility
  • Development and performance tools, including SystemTap
  • Advanced I/O performance and virtualization technologies, such as single root I/O virtualization (SRIOV)
  • Large SMP support for both physical and virtual systems
  • IPv4/IPv6 fragmentation offload and buffer management


  • Easier system configuration with many installer improvements
  • Yum/Pup-based updater for Red Hat Network
  • Conga cluster and storage management with add-ons
  • Integrated support with Red Hat Network Satellite server

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Security and storage


  • Robust SELinux implementation, including multilevel security (MLS) and targeted policies for all services
  • Internet Protocol Security (IPsec) enhancements for improved security and performance
  • Exec Shield enhancements, such as a call frame Canary word, for stronger hacker defenses
  • New audit features for powerful new search/reporting and real-time monitoring


  • Support for root device multipath I/O (MPIO) for improved availability
  • Block device data encryption support
  • Continued updates for maximum flexibility, including ext4 file system

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Red Hat Enterprise Linux Desktop

  • Foundational Stateless Linux features, including X autoconfigure and NetworkManager
  • Improved ACPI support with features like suspend to disk
  • Smart card login with public key infrastructure (PKI)/Kerberos authentication
  • Integrated multimedia support
  • Enhanced plug-and-play hardware support (including for cameras, printers, and scanners)
  • NetworkManager for automatic wired and wireless network configuration
  • Enhanced graphics using Accelerated Indirect GLX (AIGLX)/Compiz (with fading, transparency, and other features)

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Development environment, networking, and interoperability

Networking and interoperability

  • Network storage enhancements, including Autofs, FS-Cache, and Internet Small Computer System Interface (iSCSI) support
  • IPv6 support and conformance enhancements
  • Improved Microsoft file/print and Active Directory integration, including support for Windows

Development environment

  • Enhanced application development tools, including SystemTap profiler and Frysk debugger
  • GCC 4.1 and glibc 2.5 toolchain

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Version 4

Linux 2.6 kernel infrastructure

Red Hat Enterprise Linux 4 provides the most stable, robust commercial product based on the Linux community's 2.6.9 kernel. The greatly improved kernel includes many enhanced algorithms and features.

  • Generic logical CPU scheduler: Handles multicore and hyperthreaded CPUs.
  • Read-copy-update: SMP algorithm optimization for operating system data structures.
  • Enhanced SMP and Non-Uniform Memory Access (NUMA) support: Improved performance and scalability for large servers.
  • Network interrupt mitigation (NAPI): Improved performance for heavy network loads.

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Improved storage and file system capabilities

Improvements to the scalability and performance of the data storage subsystems include:

  • Ext3 performance and scalability.
  • Logical Volume Management (LVM) and a flexible management GUI.
  • Enhanced storage logical unit number (LUN) management.
  • Automounting with AutoFSv4.

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New security capabilities

Sophisticated security capabilities include:

  • Mandatory access control: SELinux provides a MAC infrastructure that complements the existing discretionary access control security features provided by the standard Linux environment.
  • Memory management: Several features, including Exec Shield and position-independent executables, combine to prevent applications from being exploited by attacks like buffer overflows.
  • Compile and runtime consistency checking: New buffer validation techniques in the GCC compiler and Glibc library reduce the risk of faulty applications being compromised.

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Enhanced desktop capabilities

The feature-rich, easy-to-use desktop environment includes:

  • Personal productivity: Get more done with the productivity suite, Firefox web browser, and Evolution email client.
  • Plug-and-play device support: Get easy handling of devices like USB disks and digital cameras.
  • Multimedia: Includes applications such as RhythmBox, HelixPlayer, Totem, and SoundJuicer.
  • User environment: GNOME 2.8 provides a consistent graphical look and feel.
  • Interoperability: Includes authentication options for Microsoft Active Directory and NT LAN Manager (NTLM).
  • IIIMF: Provides the next-generation multilingual Unicode input method framework.

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Other features

As a major new release, almost every aspect of Red Hat Enterprise Linux has been enhanced. Some other important improvements include:

  • Support for 15 languages: English, Japanese, German, Brazilian Portuguese, Korean, Italian, French, Simplified Chinese, Traditional Chinese, Spanish, Devnagari, Bangla, Punjabi, Tamil, and Gujarati.
  • Auditing: Includes comprehensive auditing capabilities for SELinux and standard Linux events.
  • File serving: Includes NFSv4 and SAMBA.
  • Advanced configuration and power interface: Supports the Advanced Configuration and Power Interface (ACPI) standard.

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Version 3

Support for multiple architectures

Red Hat Enterprise Linux 3 supports:

  • Intel X86
  • Intel Itanium2
  • AMD AMD64
  • IBM zSeries, POWER Series, and S/390

(With Update 2, delivered in May 2004, support for Intel EM64T was added.)

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Native Posix Thread Library

This high-performance multithreading capability improves performance for multithreaded applications.

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Improved scalability

Support for larger symmetric multiprocessing (SMP), memory, and I/O systems allows Red Hat Enterprise Linux 3 to support servers approximately twice the size of version 2.1.

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Improved desktop

Version 3 includes Red Hat's GNOME-based GUI and a comprehensive set of personal productivity applications.

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Bundled web solutions

Red Hat's secure web server solution, previously available as a separate layered product for Red Hat Enterprise Linux AS, has been updated to Apache version 2 and included as part of the base Red Hat Enterprise Linux product set.

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