The Red Hat Enterprise Linux graphical installer steps the user through the major steps involved in preparing a system for installation. The Red Hat Enterprise Linux 6 installation graphical installer introduces major usability enhancements for disk partitioning and storage configuration.

The graphical installer now allows a user to choose basic storage devices or specialized storage devices. Basic Storage Devices typically do not need any additional configuration settings before the device is usable. A new interface has been implemented for configuring specialized storage devices. Firmware RAID devices, Fibre Channel over Ethernet (FCoE) devices, multipath devices, and other storage area network (SAN) devices can now be easily configured using the new interface.

The interface for choosing partitioning layouts has been enhanced, providing detailed descriptions and diagrams for each default partitioning layout

The Installer allows storage devices to be specified as either install target devices or data storage devices prior to installation.

Kickstart is an automated installation method that system administrators use to install Red Hat Enterprise Linux. Using kickstart, a single file is created, containing the answers to all the questions that would normally be asked during a typical installation.

Red Hat Enterprise Linux 6 introduces improvements to the validation of kickstart files, allowing the installer to capture issues with kickstart file syntax before an installation commences.

The text-based installer is provided primarily for systems with limited resources. The text-based installer has been simplified, permitting installation to the default disk layouts, and installation of new and updated packages.

LVM supports mirrored volumes. By creating mirrored logical volumes, LVM ensures that data written to an underlying physical volume is mirrored onto a separate physical volume.

Red Hat Enterprise Linux 6 features the new LVM Application Library (lvm2app), allowing the development of LVM based storage management applications.

Traditionally, SELinux is used to define and control how an application interacts with the system. SELinux in Red Hat Enterprise Linux 6 introduces a set of policies that allows system administrators to control what particular users can access on a system.

SELinux in Red Hat Enterprise Linux 6 features the new security sandbox feature. The security sandbox adds a set of SELinux policies that enables a system administrator to run any application within a tightly confined SELinux domain. Using the sandbox, system administrators can test the processing of untrusted content without damaging the system.

The X Window System (commonly referred to a "X") provides the base framework for displaying the graphical user interface (GUI) on Red Hat Enterprise Linux 6. This release features the new X Access Control Extension (XACE), which permits SELinux to access decisions made within X, specifically, controlling information flow between window objects.

Duplicate Address Detection (DAD) is a feature of the Neighbor Discovery Protocol portion of IPv6. Specifically, DAD is tasked with checking if an IPv6 address is already being used. Red Hat Enterprise Linux features Optimistic Duplicate Address Detection, a speed optimization of DAD.

Red Hat Enterprise Linux 6 features support for the Intra-Site Automatic Tunnel Addressing Protocol (ISATAP). ISATAP is a protocol designed to assist in the transition from IPv4 to IPv6, by providing a mechanism to connect IPv6 routers and hosts over IPv4 network infrastructure.

The new Display Preferences dialog provides the ability to further customize multiple display layouts.
The new dialog provides the ability to instantly change the positioning, resolution, refresh rate and rotation settings for each individual display that is currently attached to a machine.

Red Hat Enterprise Linux 6 introduces the Intelligent Input Bus (IBus) as the default input method framework for Asian languages.

Red Hat Enterprise Linux 6 includes im-chooser, a graphical user interface to enable and configure input methods. im-chooser (located under System > Preferences > Input Method in the main menu) allows the user to easily enable and configure the input methods available on the system.

The new Indic Onscreen Keyboard (iok) is a screen based virtual keyboard for Indic languages, enabling input using Inscript keymap layouts and other 1:1 key mappings.

Red Hat Enterprise Linux 6 includes improved sorting for Indic languages. The order of menus and other interface elements are now correctly sorted in Indic languages.

Font support in Red Hat Enterprise Linux 6 has been improved, with updates to fonts for Chinese, Japanese, Korean, Indic and Thai languages.

Red Hat Enterprise Linux 6 introduces version 3.5 of the Mozilla Firefox web browser.

For details on the new features in Firefox, refer to the Firefox Release Notes

Red Hat Enterprise Linux 6 includes version 3 of the Mozilla Thunderbird email client, providing tabbed messaging, smart folders, and a message archive. For further details on new features in Thunderbird 3, refer to the Thunderbird Release Notes

Red Hat Enterprise Linux 6 features OpenOffice.org 3.1, adding support for reading a wider range of file formats, including Microsoft Office OOXML format. Additionally, OpenOffice.org has improved file locking support and has the ability to render graphics using anti-aliasing.
Full details on all the features in this version of OpenOffice.org are available in the OpenOffice.org Release Notes .

Control groups are a new feature of the Linux kernel in Red Hat Enterprise Linux 6. Each control group is a set of tasks on a system that have been grouped together to better manage their interaction with system hardware. Control groups can be tracked to monitor the system resources that they use. Additionally, system administrators can use control group infrastructure to allow or to deny specific control groups access to system resources such as memory, CPUs (or groups of CPUs), networking, I/O, or the scheduler. Management of control groups in userspace is provided by libcgroup, enabling system administrators to create new control groups, start new processes in a specific control group and set control group parameters.

A process (or task) scheduler is a specific kernel subsystem that is responsible for assigning the order in which processes are sent to the CPU. The kernel (version 2.6.32) shipped in Red Hat Enterprise Linux 6 replaces the O(1) scheduler with the new Completely Fair Scheduler (CFS). The CFS implements the fair queuing scheduling algorithm.

Implemented by the kernel, virtual memory presents applications with a single, contiguous block of memory addresses. The reality underlying this presentation is complex, with actual physical addresses commonly fragmented and even paged out to much slower devices such as fixed disks. The virtual memory addresses are organized by the kernel into standard units called pages. The kernel in Red Hat Enterprise Linux 6 features enhanced management of virtual memory pages, reducing the processing load required on systems with large amounts of physical memory.

The kernel in Red Hat Enterprise Linux 6 features Advanced Error Reporting (AER). AER is a new kernel feature that provides enhanced error reporting for PCI-Express devices.

Kdump is now enabled by default on systems with large amounts of memory. Specifically, kdump is enabled by default on:

The kernel in Red Hat Enterprise Linux 6 features support for Aggressive Link Power Management (ALPM). ALPM is a power-saving technique that helps the disk save power by setting a SATA link to the disk to a low-power setting during idle time (i.e. when there is no I/O). ALPM automatically sets the SATA link back to an active power state once I/O requests are queued to that link.

Previously the kernel implemented a timer that periodically queried the system to check if there were any outstanding tasks to process. Consequently, the CPU would remain in an active state, consuming unnecessary power. The kernel in Red Hat Enterprise Linux 6 enables the new tickless kernel feature, replacing the periodic timer interrupts with on-demand interrupts. The tickless kernel allows a CPU to enter longer sleep states when idle, and wake only when a task is queued for processing.

The Linux Performance Counter infrastructure provides an abstraction of performance counter hardware capabilities, such as instructions executed, cache misses, and branches mis-predicted. PCL provides per-task and per-CPU counters, and adds event capabilities on top of these counters. Performance counter information can be used to profile kernel functions and events, and assist in the analysis of kernel performance issues.

Two new tools are available in Red Hat Enterprise Linux 6 to assist in analyzing kernel performance. Ftrace provides call graph style tracing for the kernel. The new perf tool monitors, logs and analyzes system hardware events.

The Physical Address Extension (PAE) is a feature implemented in modern x86 processors. PAE extends memory addressing capabilities, allowing more than 4 gigabytes (GB) of random access memory (RAM) to be used. The default kernel shipped with the x86 architecture version of Red Hat Enterprise Linux 6 is PAE enabled. A PAE enabled processor is a minimum requirement for the x86 variant of Red Hat Enterprise Linux 6.

Firmware files for which there is no appropriately licensed source code have been removed from the Red Hat Enterprise Linux 6 kernel. Modules that require loadable firmware now use a kernel interface to request firmware from userspace.

The KVM hypervisor in Red Hat Enterprise Linux 6 features Kernel SamePage Merging (KSM), allowing KVM guests to share identical memory pages. Page sharing reduces memory duplication, allowing a host with similar guest operating systems to run more efficiently.

Assignment devices can now be hot plugged and hot removed from running guests.

The para-virtualized serial device (virtio-serial) provides a simple communication interface between the host's user space and the guest's user space. virtio-serial can be used for communication where networking is not be available or unusable.

sVirt is a new feature included with Red Hat Enterprise Linux 6.0 that integrates SELinux and virtualization. sVirt applies Mandatory Access Control (MAC) to improve security when using virtualized guests. sVirt improves security and hardens the system against bugs in the hypervisor that might be used as an attack vector for the host or to another virtualized guest.

As part of the new qdev device model, the guest ABI is now stable and will be kept consistent for newer releases. The devices and device arrangements on guests will remain consistent in future updates. This feature resolves issues with some operating system activation processes.

Red Hat Enterprise Linux 6 features enhanced installation crash reporting in the installer. Refer to Section 2.4, “Installation Crash Reporting”