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3.4. General Information
This section contains general information not specific to any other section of this document.
- Red Hat Enterprise Linux Deployment Guide
- This release of Red Hat Enterprise Linux includes a fairly comprehensive Deployment Guide. To access it, go to (on the top panel) => => Red Hat Enterprise Linux .It is the intention of Red Hat to provide fully localized versions of the Deployment Guide for all supported languages. If you have installed a localized version of the Deployment Guide, it is recommended that you update it when a new version becomes available through Red Hat Network.
- Web Server Packaging Changes
- Red Hat Enterprise Linux 5 now includes version 2.2 of the Apache HTTP Server. This release brings a number of improvements over the 2.0 series, including:
- improved caching modules (
mod_cache,mod_disk_cache,mod_mem_cache) - a new structure for authentication and authorization support, replacing the authentication modules provided in previous versions
- support for proxy load balancing (
mod_proxy_balancer) - support for handling large files (namely, greater than 2GB) on 32-bit platforms
The following changes have been made to the default httpd configuration:- The
mod_cern_metaandmod_asismodules are no longer loaded by default. - The
mod_ext_filtermodule is now loaded by default.
If you are 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.Note that any third-party modules compiled for httpd 2.0 must be rebuilt for httpd 2.2. - php
- Version 5.1 of PHP is now included in Red Hat Enterprise Linux 5, 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:The
/usr/bin/phpexecutable is now built using the CLI command-line SAPI, rather than the CGI SAPI. Use/usr/bin/php-cgifor CGI SAPI. Thephp-cgiexecutable also includes FastCGI support.The following extension modules have been added:- the mysqli extension, a new interface designed specifically for MySQL 4.1 (included in the
php-mysqlpackage) - date, hash, Reflection, SPL and SimpleXML (built-in with the php package)
pdoandpdo_psqlite(in thephp-pdopackage)pdo_mysql(in thephp-mysqlpackage)pdo_pgsql(in thephp-pgsqlpackage)pdo_odbc(in thephp-odbcpackage)soap(in thephp-soappackage)xmlreaderandxmlwriter(in thephp-xmlpackage)dom(replacing the domxml extension in thephp-xmlpackage)
The following extension modules are no longer included:dbxdioypoverloaddomxml
- The PEAR Framework
- The PEAR framework is now packaged in the
php-pearpackage. Only the following PEAR components are included in Red Hat Enterprise Linux 5:- Archive_Tar
- Console_Getopt
- XML_RPC
- Encrypted Swap Partitions and Non-root File Systems
- Red Hat Enterprise Linux 5 now provides basic support for encrypted swap partitions and non-root file systems. To use these features, add the appropriate entries to
/etc/crypttaband reference the created devices in/etc/fstab.Below is a sample/etc/crypttabentry: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/crypttabentry for a file system volume:my_volume /dev/hda5 /etc/volume_key cipher=aes-cbc-essiv:sha256
The/etc/volume_keyfile contains a plaintext encryption key. You can also specifynoneas the key file name; this configures the system to ask for the encryption key during boot instead.It is recommended to use LUKS (Linux Unified Key Setup) for setting up file system volumes. To do this, follow these steps:- Create the encrypted volume using
cryptsetup luksFormat. - Add the necessary entry to
/etc/crypttab. - Set up the volume manually using
cryptsetup luksOpen(or reboot). - Create a file system on the encrypted volume.
- Add the necessary entry to
/etc/fstab.
- mount and umount
- The
mountandumountcommands no longer directly support NFS; a built-in NFS client no longer exists. A separatenfs-utilspackage, which provides/sbin/mount.nfsand/sbin/umount.nfshelpers, must be installed for this. - CUPS Printer Browsing
- 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.confon the clients and replaceBrowseAllow @LOCALwithBrowseAllow ALL. - ATI and R500 Support
- ATI graphics cards based on the R500 chipset are supported for the
vesadriver only, and are not supported by Red Hat Enterprise Linux 5 on external monitors, LCD projectors or accelerated 3D support. - up2date and yum
up2dateis being deprecated in favor ofyum(Yellowdog Updater Modified). As such, it is advisable that you revise anyup2date-dependent scripts your system is using accordingly. For more information aboutyum, consult its man page with the commandman yum; you can also consult the installed documentation under the directories/usr/share/doc/yum-<version>and/usr/share/doc/yum-metadata-parser-<version>(replace<version>with the corresponding version ofyumandyum-metadata-parserinstalled).- OpenLDAP Server and Red Hat Directory Server
- Red Hat Directory Server is an LDAP-based server that centralizes enterprise and network data into an OS-independent, network-based registry. It is set to replace OpenLDAP server components, which will be deprecated after Red Hat Enterprise Linux 5. For more information about Red Hat Directory Server, refer to http://www.redhat.com/software/rha/directory/.
- i810 Driver and i830 Support
- The i810 driver supports all integrated Intel graphics chipsets, from i810 to i965. However, the support for i830 (and newer) chipsets is limited; the i810 driver can only set modes listed in the video BIOS. If your machine has an i830 or newer chipset installed, run the following command to determine what the available modes are:
grep Mode: /var/log/Xorg.0.logModes marked with an asterisk (*) are available for selection.Many laptop video BIOSes do not supply a mode that matches the native panel size. Therefore the chosen mode may appear stretched, distorted, or with black borders. As such, if your chosen mode does not display properly, you need a BIOS update from your hardware vendor for the native panel size to work correctly. - Intel PRO/Wireless 3945ABG Network Connection Support
- This release of Red Hat Enterprise Linux 5 includes support for the ipw3945 (Intel PRO/Wireless 3945ABG Network Connection) adapter. The Red Hat Enterprise Linux 5 Supplementary disc contains the driver, regulatory daemon and firmware needed to support this adapter.To enable support for the ipw3945 wireless adapter, search the Red Hat Enterprise Linux 5 Supplementary disc for packages with filenames containing "3945" and install them.
- rawio
- rawio is a deprecated interface; however, Red Hat Enterprise Linux 5 still includes support for it. If you have an application that performs device access using rawio, it is highly recommended that you modify your application to open the block device with the
O_DIRECTflag. The rawio interface will remain throughout the life of Red Hat Enterprise Linux 5, but is a candidate for removal in a future release.Currently, AIO (Asynchronous I/O) on file systems is only supported inO_DIRECTor non-buffered mode. Further, note that the asynchronous poll interface is no longer present, and that AIO on pipes is no longer supported. - ctmpc
- ctmpc is a deprecated driver; however, it will still be included throughout the life of Red Hat Enterprise Linux 5. Note that it is a candidate for removal from future releases.
- Policy Modules and semanage Support
- Red Hat Enterprise Linux 5 now supports policy modules and semanage. Policy modules simplify the creation and distribution of policy customizations and third-party policies through the use of the
semoduleandcheckmoduletools.Thesemanagetool is a policy management tool that modifies the SELinux configuration. It also allows you to configure file contexts, networking component labeling, and user mappings for Linux-to-SELinux. - raw Device Mapping
- The
rawdevices interface has been deprecated in Red Hat Enterprise Linux 5;rawdevice mapping is now configured viaudevrules.To configurerawdevice mapping, add the appropriate entries to/etc/udev/rules.d/60-raw.rulesin the following formats:- For device names:
ACTION=="add", KERNEL="<device name>", RUN+="raw /dev/raw/rawX %N"
- For major / minor numbers:
ACTION=="add", ENV{MAJOR}="A", ENV{MINOR}="B", RUN+="raw /dev/raw/rawX %M %m"
Replace <device name> with the name of the device you need to bind (for example,/dev/sda1). "A" and "B" are the major / minor numbers of the device you need to bind, and X is the raw device number that you want the system to use.If you have a large, pre-existing/etc/sysconfig/rawdevicesfile, convert it with the following script:#!/bin/sh grep -v "^ *#" /etc/sysconfig/rawdevices | grep -v "^$" | while read dev major minor ; do if [ -z "$minor" ]; then echo "ACTION==\"add\", KERNEL==\"${major##/dev/}\", RUN+=\"/usr/bin/raw $dev %N\"" else echo "ACTION==\"add\", ENV{MAJOR}==\"$major\", ENV{MINOR}==\"$minor\", RUN+=\"/usr/bin/raw $dev %M %m\"" fi done - QLogic Support
- Red Hat Enterprise Linux 5 supports the QLogic family of iSCSI HBA (Host Bus Adapters). At present, only the iSCSI interface to these boards are supported (using the
qla4xxxdriver).In addition, Red Hat does not currently support these boards as Ethernet NIC, as this capability requires theqla3xxxdriver. This issue will be addressed in an upcoming minor release of Red Hat Enterprise Linux 5. - IBM System z Instruction Set
- In order to optimally exploit the IBM System z instruction set for 31-bit applications, it is recommended that you use the
gccoption-march=z900. For 64-bit applications, thegccwill exploit the IBM System z instruction set by default. - iSeries Access for Linux
- The iSeries ODBC Driver for Linux has been replaced by the iSeries Access for Linux, which can be downloaded at the following link:The iSeries Access for Linux offers Linux-based access to iSeries servers, and allows you to:
- Access the DB2 UDB (Universal Database) for iSeries using its ODBC Driver
- Establish a 5250 session to an iSeries server from a Linux client
- Access the DB2 UDB via the EDRS (Extended Dynamic Remote SQL) driver
- Support 32-bit (i386 and PowerPC) and 64-bit (x86-64 and PowerPC) platforms
- IBM Power4 iSeries
- Red Hat Enterprise Linux no longer supports the IBM Power4 iSeries.
- kdump Minimum Memory
kdumpreserves a significant amount of memory at boot time, which changes the actual minimum memory requirements of Red Hat Enterprise Linux 5. To compute the actual minimum memory requirements for your system, refer to http://www.redhat.com/rhel/details/limits/ for the listed minimum memory requirements; then, add the amount of memory used bykdumpto determine the actual minimum memory requirements.
