Included in this beta of Red Hat Enterprise Linux 4.92 are enabling infrastructure pieces for Stateless Linux. Stateless Linux is a new way of thinking about how a system is to be run and managed, designed to simplify provisioning and management of large numbers of systems by making them easily replaceable. This is primarily accomplished by establishing prepared system images which get replicated and managed across a large number of stateless systems, running the operating system in a read-only manner.

In its current state of development, the Stateless features are subsets of the intended goals. As such, the capability is being labeled as a technology preview.

The following is a list of the initial capabilities included in Red Hat Enterprise Linux 4.92 beta:

It is currently not possible to run Stateless Linux on a local file system with changes synchronized from a master server, due to required kernel changes.

It is highly recommended that those interested in testing stateless code read the HOWTO at http://fedoraproject.org/wiki/StatelessLinuxHOWTO and join stateless-list@redhat.com.

GFS2 is an evolutionary advancement based on the GFS file system. While fully functional, GFS2 is not yet considered production-ready. GFS, which has been in production for 5 years, is being provided with this release and is fully supported for non-clustered data file systems (except for root and boot), as well as in clustered file system configurations on shared storage when the cluster infrastructure is present. GFS2 is targeted to move to a fully supported status in a subsequent Red Hat Enterprise Linux 4.92 update. There is also an in-place conversion utility, gfs2_convert, which can update the meta data of a GFS file system, converting it to a GFS2 file system.

FS-Cache is a local caching facility for remote file systems; it allows users to cache NFS data on a locally mounted disk. To set up the FS-Cache facility, install the cachefilesd RPM and refer to the instructions in /usr/share/doc/cachefilesd-<version>/README.

Replace <version> with the corresponding version of the cachefilesd package installed.

Compiz is an OpenGL-based compositing window manager. In addition to regular window management, compiz also acts as a compositing manager. In this role, compiz coordinates and synchronizes the overall desktop redrawing to provide a smoother desktop experience with less flicker and a more solid feel.

Compiz uses 3D hardware acceleration to render effects such as live thumbnail windows and window drop shadows, as well as animated window minimizing and transitions between virtual desktops.

Due to limitations in the current rendering architecture, compiz cannot work correctly with direct rendering OpenGL applications or applications using the Xv extension. Such applications will exhibit harmless rendering artifacts; because of this, the feature is currently not supported fully.

In Red Hat Enterprise Linux 4.92, the EXT3 file system capacity has been extended beyond 8TB to a maximum of 16TB. This capability is being included as a technology preview, and is targeted for full support in a future release of Red Hat Enterprise Linux 4.92.

Red Hat Enterprise Linux 4.92 features virtualization capabilities for i686 and x86-64, as well as the software infrastructure needed to manage a virtualized environment.

The implementation of virtualization in Red Hat Enterprise Linux 4.92 is based on the hypervisor, which facilitates extremely low overhead virtualization through paravirtualization. With Intel Virtualization Technology or AMD AMD-V capable processors, virtualization in Red Hat Enterprise Linux 4.92 allows operating systems to run unmodified in fully virtualized mode.

Virtualization on Red Hat Enterprise Linux 4.92 also features the following:

Red Hat Network also supports virtual machines.

Red Hat Enterprise Linux 4.92 now includes version 2.2 of the Apache HTTP Server. This release brings a number of improvements over the 2.0 series, including:

The following changes have been made to the default httpd configuration:

If upgrading from a previous release of Red Hat Enterprise Linux, the httpd configuration will need to be updated for httpd 2.2. For more information, refer to http://httpd.apache.org/docs/2.2/upgrading.html.

Any third-party modules compiled for httpd 2.0 must be rebuilt for httpd 2.2.

Version 5.1 of PHP is now included in Red Hat Enterprise Linux 4.92, which includes a number of changes to the language along with significant performance improvements. Some scripts might need to be edited for use with the new version; please refer to the link below for more information on migrating from PHP 4.3 to PHP 5.1:

http://www.php.net/manual/en/migration5.php

The /usr/bin/php executable is now built using the CLI command-line SAPI, rather than the CGI SAPI. Use /usr/bin/php-cgi for CGI SAPI. The php-cgi executable also includes FastCGI support.

The following extension modules have been added:

The following extension modules are no longer included:

The PEAR framework is now packaged in the php-pear package. Only the following PEAR components are included in Red Hat Enterprise Linux 4.92:

On Red Hat Enterprise Linux 4.92, it is possible to build updated kernel module packages that depend upon the current kernel ABI version and not on a specific kernel release number. This facilitates building kernel modules that can be used against a range of Red Hat Enterprise Linux 4.92 kernels, rather than a single release. The project website at http://www.kerneldrivers.org/ contains more information about the packaging process, as well as several examples.

Red Hat Enterprise Linux 4.92 now provides basic support for encrypted swap partitions and non-root file systems. To use these features, add the appropriate entries to /etc/crypttab and reference the created devices in /etc/fstab.

Below is a sample /etc/crypttab entry:

my_swap /dev/hdb1 /dev/urandom swap,cipher=aes-cbc-essiv:sha256
			

This creates the encrypted block device /dev/mapper/my_swap, which can be referenced in /etc/fstab.

Below is a sample /etc/crypttab entry for a file system volume:

my_volume /dev/hda5 /etc/volume_key cipher=aes-cbc-essiv:sha256
			

The /etc/volume_key file contains a plaintext encryption key. You can also specify none as the key file name, at which the system will ask for the encryption key during boot instead.

It is recommended to use LUKS for setting up file system volumes. To do this, follow these steps:

The mount and umount commands no longer directly support NFS; there no longer is a built-in NFS client. A separate nfs-utils package, which provides /sbin/mount.nfs and /sbin/umount.nfs helpers, must be installed for this.

CUPS printer browsing over a local subnet can be configured using the graphical tool system-config-printer. It can also be done using the CUPS web interface, http://localhost:631/.

To use directed broadcasts for printer browsing between subnets, open /etc/cups/cupsd.conf on the clients and change BrowseAllow @LOCAL to BrowseAllow ALL.

SCIM (Smart Common Input Method) has replaced IIIMF as the input method system for Asian and other languages in this release. The default GTK Input Method Module for SCIM is provided by scim-bridge; in Qt, it is provided by scim-qtimm.

Below are the default trigger hotkeys for different languages:

If SCIM is installed, it runs by default for all users.

SCIM is installed by default for most Asian installations. Otherwise, you can use the package manager (pirut) to install additional language support using the "Languages" component, or run this command:

su -c 'yum groupinstall <language>-support'
			

In the command above, <language> can be either Assamese, Bengali, Chinese, Gujarati, Hindi, Japanese, Kannada, Korean, Malayalam, Marathi, Oriya,Punjabi, Sinhala, Tamil, Thai, or Telugu.

A new user configuration tool called im-chooser has been added, which allows you to easily disable or enable the usage of input methods on your desktop. So if SCIM is installed but you do not wish to run it on your desktop, you can disable it using im-chooser.

At X startup, xinput.sh now sources ~/.xinputrc or /etc/X11/xinit/xinputrc instead of searching config files under ~/.xinput.d/ or /etc/xinit/xinput.d/.

Firefox in Red Hat Enterprise Linux 4.92 is built with Pango, which provides better support for certain scripts, such as Indic and some CJK scripts.

To disable the use of Pango, set MOZ_DISABLE_PANGO=1 in your environment before launching Firefox.

Support is now available for synthetic emboldening of fonts that do not have a bold face.

New fonts for Chinese have been added: AR PL ShanHeiSun Uni (uming.ttf) and AR PL ZenKai Uni (ukai.ttf). The default font is AR PL ShanHeiSun Uni, which contains embedded bitmaps. If you prefer outline glyphs, you can add the following section in your ~/.font.conf file:

<fontconfig>
  <match target="font">
    <test name="family" compare="eq">
      <string>AR PL ShanHeiSun Uni</string>
    </test>
    <edit name="embeddedbitmap" mode="assign">
      <bool>false</bool>
    </edit>
  </match>
</fontconfig>				
			

The Gtk2 context menu IM submenu no longer appears by default. You can enable it on the command line with the following command:

gconftool-2 --type bool --set '/desktop/gnome/interface/show_input_method_menu' true
			

CJK (Chinese, Japanese, and Korean) rendering support has been removed from the Anaconda text installation. The text installation method is being deprecated in the long term, as the GUI installation, VNC and kickstart methods are preferred.

The following packages are deprecated and scheduled for removal in Red Hat Enterprise Linux:

These packages are being deprecated in favor of the gtk2 stack, which offers better functionality particularly in terms of internationalization and font handling.

If you need to display Chinese, Japanese, or Korean on the console, you need to setup a framebuffer. To do this, install bogl and bogl-bterm, and run bterm on the framebuffer. Note that the kernel framebuffer module depends on the graphics chipset in your machine.