Red Hat Enterprise Linux 5.2

Release Notes for x86

Red Hat Enterprise Linux Documentation

Don Domingo

Engineering Services and Operations
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Some updates on Red Hat Enterprise Linux 5.2 may not appear in this version of the Release_Notes. An updated version may also be available at the following URL:

1. Release Notes Updates
2. Installation-Related Notes
3. Feature Updates
4. Driver Updates
5. Kernel-Related Updates
6. Virtualization
7. Technology Previews
8. Resolved Issues
9. Known Issues

1. Release Notes Updates

This section contains information about Red Hat Enterprise Linux 5.2 that did not make it into the Release Notes included in the distribution.

  • Thin Provisioning (also known as "virtual provisioning") will be first released with EMC Symmetrix DMX3 and DMX4. Please refer to the EMC Support Matrix and Symmetrix Enginuity code release notes for further details.

  • Recording needs to be manually enabled on Dell M4300 and M6300. To do this, perform the following steps:

    1. Open alsamixer.

    2. Press Tab to toggle [Capture] in the View field (located at the upper left part of the menu).

    3. Press the Space bar.

    4. To verify that recording is enabled, the text above the ADCMux field should display L R CAPTUR.

  • dom0 has a system-wide IRQ (interrupt request line) limit of 256, which is consumed as follows:

    • 3 per physical CPU.

    • 1 per guest device (i.e. NIC or block device)

    When the IRQ limit is reached, the system will crash. As such, check your IRQ consumption to make sure that the number of guests you create (and their respective block devices) do not exhaust the IRQ limit.

    To determine how many IRQs you are currently consuming, run the command grep Dynamic-irq /proc/interrupts | wc -l.

  • In /etc/multipath.conf, setting max_fds to unlimited will prevent the multipathd daemon from starting up properly. As such, you should use a sufficiently high value instead for this setting.

  • When provisioning guests during installation, the RHN tools for guests option will not be available. When this occurs, the system will require an additional entitlement, separate from the entitlement used by dom0.

    To prevent the consumption of additional entitlements for guests, install the rhn-virtualization-common package manually before attempting to register the system to Red Hat Network.

  • virt-manager should not be left running continuously, as its memory use will grow over time. This could cause memory starvation.

    As such, you should only use virt-manager when needed. When extended use is required, it is advisable to periodically exit and restart virt-manager.

  • Network driver r8169 updated to add support for the following devices:

    • RTL8169sb/8110sb

    • RTL8169sc/8110sc

    • RTL8168b/8111b

    • RTL8101e

    • RTL8100e

  • The crash utility cannot be used to analyze kdump-generated x86_64 vmcores using the xen-syms-[release] binary of the Red Hat Enterprise Linux 5.2 kernel. To read these types of vmcores, use the command crash --xen_phys_start [address] /boot/xen-syms-[version] vmcore instead.

    To determine the value of [address], run the command cat /proc/iomem | grep Hypervisor. Something similar to the following output should appear:

    3ee00000-3fdfffff : Hypervisor code and data

    The [address] is the first number in the stated range; in this case, it is 3ee00000.

  • When installing Red Hat Enterprise Linux 5 on a guest, the guest is configured to explicitly use a temporary installation kernel provided by dom0. Once installation finishes, it can then use its own bootloader. However, this can only be achieved by forcing the guest's first reboot to be a shutdown.

    As such, when the Reboot button appears at the end of the guest installation, clicking it shuts down the guest, but does not reboot it. This is an expected behavior.

    Note that when you boot the guest after this it will then use its own bootloader.

  • Running rpmbuild on the compiz source RPM will fail if any KDE or qt development packages (for example, qt-devel) are installed. This is caused by a bug in the compiz configuration script.

    To work around this, remove any KDE or qt development packages before attempting to build the compiz package from its source RPM.

  • If your system has either ATI Radeon R500 or R600 graphics card equipped, firstboot will not run after installation. The system will go directly to the graphical login screen and skip firstboot altogether. If you attempt to run firstboot manually (i.e. from a failsafe terminal), the X session will crash.

    This issue is caused by the driver used by the ATI Radeon R500/R600 hardware. The default driver used by these graphics cards are still in technology preview. To work around this, backup your /etc/X11/xorg.conf file; then, configure X to use the supported vesa driver instead using the following command:

    system-config-display --reconfig --set-driver=vesa

    You can now run firstboot. To switch back to your old settings, restore your original /etc/X11/xorg.conf.

  • nfsroot is fully supported in this update. This allows users to run Red Hat Enterprise Linux 5.2 with its root file system (/) mounted via NFS.

    nfsroot was originally introduced in Red Hat Enterprise Linux 5 as a subset of the Technology Preview feature Stateless Linux. The full implementation of Stateless Linux remains a Technology Preview.

    At present, nfsroot has the following restrictions:

    • Writable directories that hold system files (for example, /tmp, /var, and /etc) must be replicated for each client and mounted independently with no sharing between clients. To do so, perform the following steps:

      1. Configure the client's root file system to boot in read-only mode. To do so, set READONLY to yes in /etc/sysconfig/readonly-root.

      2. Run cat /etc/rwtab to view a default list of directories and files mounted by each client in the format [type] [path].

        [type] can be either empty (an empty path), dirs (a directory tree that is copied, but is empty), or files (a file or directory tree copied intact).

      3. If any other files or directories need to writable but are not in /etc/rwtab, list them in the same format (i.e. [type] [path]) in a file under /etc/rwtab.d/. You may use any filename for this file.

    • SWAP is not supported over NFS.

    • SELinux cannot be enabled on nfsroot clients. In general, Red Hat does not recommend disabling SELinux. As such, customers must carefully consider the security implications of this action.

  • Installing Red Hat Enterprise Linux 5.2 on a system with multiple network interfaces and manually specified IPv6 addresses may result in a partially incorrect networking setup. When this occurs, your IPv6 settings will not be visible on the installed system.

    To work around this, set NETWORKING_IPV6 to yes in /etc/sysconfig/network. Then, restart your network connection using the command service network restart.

  • If your system uses the TSC timer, the gettimeofday system call may move backwards. This is because of an overflow issue that causes the TSC timer to jump forward significantly in some cases; when this occurs, the TSC timer will correct itself, but will ultimately register a movement backwards in time.

    This issue is particularly critical for time-sensitive systems, such as those used for transaction systems and databases. As such, if your system needs precision timing, Red Hat strongly recommends that you set the kernel to use another timer (for example, HPET).

  • The READ_AHEAD setting in the cciss driver is now removed. The cciss driver will now use the block layer default of 256. Testing has shown that the setting READ_AHEAD=1024 did not result in a consistent improvement in performance; in some situations, this setting could also cause the system to hang.

  • When multiple NFSv4 clients are repeatedly competing for read/write access to the same file on the NFS server, it is possible for one or more of those clients to stall for an indefinite period of time waiting for access. This occurs because the standard delay observed when failing to get an access delegation from the server is long enough for the client who currently owns such delegation to return it to the server and claim it back again.

  • If your system has yum-rhn-plugin-0.5.2-5.el5_1.2 (or an earlier version) installed, you will be unable to upgrade to Red Hat Enterprise Linux 5.2 through yum update. To work around this, upgrade your yum-rhn-plugin to the latest version (using yum update yum-rhn-plugin) before running yum update.

  • If your system has an older version of the gfs2-kmod package installed but the yum-kmod package is not installed, upgrading from Red Hat Enterprise Linux 5.1 to 5.2 will fail. To prevent this, install the latest version of yum-kmod first (using yum install yum-kmod) before running yum update.

  • Thanks to the help of upstream developers and testing customers, the FS-Cache feature has undergone significant changes in line with upstream FS-Cache implementation. Consequently, the technology preview implementation of FS-Cache in this release is now rendered obsolete.

    As such, Red Hat does not recommend the usage of FS-Cache. Note that FS-Cache will also be likely disabled for the next minor releases.

    Red Hat will be focusing on further refining this feature as per upstream specifications. Once an acceptable level of invasiveness and compatibility is reached, FS-Cache will then be re-introduced in Red Hat Enterprise Linux.

  • Anaconda cannot access more than 8 SmartArray controllers. If your system has more than 8 such controllers equipped, you will only be able to use storage on the first 8 controllers detected. Anaconda will fail when it attempts to open all other controllers (i.e. the 9th controller and above).

    Note, however, that these devices will still function properly after installation.

  • Firefox is now updated to version 3.0. This update features several fixes and enhancements, most notably:

    • Set homepages are now loaded correctly when the Firefox browser window is opened.

    • Firefox no longer crashes when you search for the string "do".

    • Firefox in 64-bit mode now loads the ext JavaScript library correctly. In previous versions of Firefox, web-based applications that used this library either took too long to load, or were never loaded at all.

    • A cross-site scripting flaw was discovered in the way Firefox handled the jar:URI scheme. This flaw made it possible for a malicious web site to conduct a scripting attack against the user. This security issue is now fixed in this update.

    • Several flaws were discovered in the way Firefox processed certain malformed content. Web sites that contained such content could cause Firefox to crash or even execute arbitrary code as the user running Firefox. This security issue is now fixed in this update.

    • A race condition was discovered in the way Firefox set the window.location property on a web page. With this flaw, it was possible for a web page to set an arbitrary Referer header; this could lead to a cross-site request forgery (CSRF) attack against websites that rely only on the Referer header. This security issue is now fixed in this update.

    • Firefox now renders correctly on laptops equipped with external display.

    Note, however, that this update of Firefox is not fully backwards compatible with all JavaScripts or Firefox plugins used today.

    Also, Red Hat has observed that several large commercial web applications have relied on the presence of some cross-site scripting flaws addressed by this Firefox update. These scripting flaws are described in the following links:

    Consequently, the use of these commercial web applications may result in some loss of functionality. You can observe this in the presence of additional JavaScript errors in the Firefox Error Console (Tools => Error Console). Red Hat is currently working with the corresponding vendors to address this.

2. Installation-Related Notes

This section includes information specific to Anaconda and the installation of Red Hat Enterprise Linux 5.2.

Red Hat Network can install the new and changed packages and upgrade an existing Red Hat Enterprise Linux 5 system. Alternatively, Anaconda can upgrade an existing Red Hat Enterprise Linux 5 system or perform a fresh installation of Red Hat Enterprise Linux 5.2.

Note: upgrading from beta releases of Red Hat Enterprise Linux 5.2 to this GA release is not supported.

Further, although Anaconda provides an option for upgrading from earlier major versions of Red Hat Enterprise Linux to Red Hat Enterprise Linux 5.2, Red Hat does not currently support this. More generally, Red Hat does not support in-place upgrades between any major versions of Red Hat Enterprise Linux. (A major version is denoted by a whole number version change. For example, Red Hat Enteprise Linux 4 and Red Hat Enterprise Linux 5 are both major versions of Red Hat Enterprise Linux.)

In-place upgrades across major releases do not preserve all system settings, services or custom configurations. Consequently, Red Hat strongly recommends fresh installations when upgrading from one major version to another.

  • A version naming issue in the updated libdhcp6client may cause some package upgrades to fail. To work around this, manually remove the Red Hat Enterprise Linux 5.1 version of libdhcp6client before performing an upgrade to Red Hat Enterprise Linux 5.2.

  • When installing from CD-ROM or DVD-ROM on a system with an iBFT-configured network device, Anaconda will not include any iBFT-configured storage devices unless networking is configured. To enable networking for the installation, use the command linux updates=http://[any] at the installation boot prompt. Note that [any] can be replaced with any URL.

    If your system requires a static IP configuration, use the command linux updates=http://[any] ip=[IP address] netmask=[netmask] dns=[dns].

  • If you are copying the contents of the Red Hat Enterprise Linux 5 CD-ROMs (in preparation for a network-based installation, for example) be sure to copy the CD-ROMs for the operating system only. Do not copy the Supplementary CD-ROM, or any of the layered product CD-ROMs, as this will overwrite files necessary for Anaconda's proper operation.

    The contents of the Supplementary CD-ROM and other layered product CD-ROMs must be installed after Red Hat Enterprise Linux 5.2 is installed.

  • When installing Red Hat Enterprise Linux 5.2 on a fully virtualized guest, do not use the kernel-xen kernel. Using this kernel on fully virtualized guests can cause your system to hang.

    If you are using an Installation Number when installing Red Hat Enterprise Linux 5.2 on a fully virtualized guest, be sure to deselect the Virtualization package group during the installation. The Virtualization package group option installs the kernel-xen kernel.

    Note that paravirtualized guests are not affected by this issue. Paravirtualized guests always use the kernel-xen kernel.

  • If you are using the Virtualized kernel when upgrading from Red Hat Enterprise Linux 5 to 5.2, you must reboot after completing the upgrade. You should then boot the system using the updated Virtualized kernel.

    The hypervisors of Red Hat Enterprise Linux 5 and 5.2 are not ABI-compatible. If you do not boot the system after upgrading using the updated Virtualized kernel, the upgraded Virtualization RPMs will not match the running kernel.

  • When upgrading to Red Hat Enterprise Linux 5.1 or later from Red Hat Enterprise Linux 4.6, gcc4 may cause the upgrade to fail. As such, you should manually remove the gcc4 package before upgrading.

  • The firstboot language plugin has been removed, as it does not properly and completely reconfigure the system when a new language is selected.

  • The use of Challenge Handshake Authentication Protocol (CHAP) during installation is not supported. As such, CHAP should only be enabled after installation.

    If your system boots through an iFBT device, configure CHAP in the iFBT BIOS/firmware setup screen. Your CHAP settings will then be used in the next boot.

    If your system boots through PXE iSCSI, configure CHAP through iscsiadm. After configuring, use mkinitrd to ensure that your CHAP settings are used in the next boot.

3. Feature Updates


Systemtap is a GPL-based infrastructure which simplifies information gathering on a running Linux system. This assists in diagnosis of performance or functional problems. With systemtap, the tedious and disruptive "instrument, recompile, install, and reboot" sequence is no longer needed to collect diagnostic data.

Systemtap is now fully supported. For more information refer to


The Internet storage name service for Linux (isns-utils) is now supported. This allows you to register iSCSI and iFCP storage devices on the network. isns-utils allows dynamic discovery of available storage targets through storage initiators.

isns-utils provides intelligent storage discovery and management services comparable to those found in fibre-channel networks. This allows an IP network to function in a similar capacity to a storage area network.

With its ability to emulate fibre-channel fabric services, isns-utils allows for seamless integration of IP and fibre-channel networks. In addition, isns-utils also provides utilities for managing both iSCSI and fibre-channel devices within the network.

For more information about isns-utils specifications, refer to For usage instructions, refer to /usr/share/docs/isns-utils-[version]/README and /usr/share/docs/isns-utils-[version]/README.redhat.setup.


rsyslog is an enhanced multi-threaded syslogd daemon that supports the following (among others):

  • MySQL

  • syslog/tcp

  • RFC 3195

  • permitted sender lists

  • filtering on any message part

  • more granular output format control

rsyslog is compatible with the stock sysklogd, and can be used as a replacement in most cases. Its advanced features make it suitable for enterprise-class, encrypted syslog relay chains; at the same time, its user-friendly interface is designed to make setup easy for novice users.

For more information about rsyslog, refer to


Openswan is a free implementation of Internet Protocol Security (IPsec) and Internet Key Exchange (IKE) for Linux. IPsec uses strong cryptography to provide authentication and encryption services. These services allow you to build secure tunnels through untrusted networks. Everything passing through the untrusted network is encrypted by the IPsec gateway machine and decrypted by the gateway at the other end of the tunnel. The resulting tunnel is a virtual private network (VPN).

This release of Openswan supports IKEv2 (RFC 4306, 4718) and contains an IKE2 daemon that conforms to IETF RFCs. For more information about Openswan, refer to


The Evolution update for this release now features the following enhancements (among others):

  • Bogofilter compatibility for filtering junk mail.

  • An option to receive pop-up notifications for new mail.

  • Improved performance for downloading messages from a Microsoft Exchange™ server.

  • A setup assistant to guide you through both backing up and restoring data and settings.


Thunderbird has been updated to version This update applies the following features (among others):

  • Message tags, which help organize email.

  • Built-in support for Google Mail and .Mac mail.

  • Find-as-you-type, which highlights and filters message text as you type.

  • An updated extension system, which provides enhanced security and allows easier extension localization.

For more information about this update, refer to

Password Hashing Using SHA-256/SHA-512

Password hashing using the SHA-256 and SHA-512 hash functions is now supported.

To switch to SHA-256 or SHA-512 on an installed system, run authconfig --passalgo=sha256 --update or authconfig --passalgo=sha512 --update. To configure the hashing method through a GUI, use authconfig-gtk. Existing user accounts will not be affected until their passwords are changed.

For newly installed systems, using SHA-256 or SHA-512 can be configured only for kickstart installations. To do so, use the --passalgo=sha256 or --passalgo=sha512 options of the kickstart command auth; also, remove the --enablemd5 option if present.

If your installation does not use kickstart, use authconfig as described above. After installation, change all created passwords, including the root password.

Appropriate options were also added to libuser, pam, and shadow-utils to support these password hashing algorithms. authconfig configures necessary options automatically, so it is usually not necessary to modify them manually:

  • New values of the crypt_style option and new options for both hash_rounds_min and hash_rounds_max are now supported in the [defaults] section of /etc/libuser.conf. For more information, refer to man libuser.conf.

  • New options sha256, sha512, and rounds are now supported by the pam_unix PAM module. For more information, refer to /usr/share/doc/pam-[pam version]/txts/README.pam_unix.

  • The following new options in /etc/login.defs are now supported by shadow-utils:

    • ENCRYPT_METHOD — Specifies the encryption methods to be used. Valid values are DES, MD5, SHA256, and SHA512. If this option is defined, MD5_CRYPT_ENAB is ignored.

    • SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS — Specifies the number of hashing rounds to use if ENCRYPT_METHOD is set to SHA256 or SHA512. If neither option is set, a default value is chosen by glibc. If only one option is set, the encryption method specifies the number of rounds.

      If both options are used, they specify an inclusive interval from which the number of rounds is chosen randomly. The selected number of rounds is limited to the inclusive interval [1000, 999999999].

OFED in comps.xml

The group OpenFabrics Enterprise Distribution is now included in comps.xml. This group contains components used for high-performance networking and clustering (for example, InfiniBand and Remote Direct Memory Access).

Further, the Workstation group has been removed from comps.xml in the Red Hat Enterprise Linux 5.2 Client version. This group only contained the openib package, which is now part of the OpenFabrics Enterprise Distribution group.


system-config-netboot is now included in this update. This is a GUI-based tool used for enabling, configuring, and disabling network booting. It is also useful in configuring PXE-booting for network installations and diskless clients.


In order to accommodate the use of compilers other than gcc for specific applications that use message passing interface (MPI), the following updates have been applied to the openmpi and lam packages:

  • MPI installations are now consolidated under a single installation directory. All files can now be found under /usr/lib(64)/lam and /usr/lib(64)/openmpi/[openmpi version]-[compiler name].

  • Version and compiler strings are now included in the openmpi installation path, but not the lam installation path. This enables you to install multiple versions of openmpi, or install the same version of openmpi built by different compilers.

    While this capability allows you to use a version of openmpi built by another compiler, Red Hat only supports the latest, gcc-compiled version of openmpi.

  • openmpi and lam now use mpi-selector to set which MPI implementation to use at any given time. For more information, refer to man mpi-selector and man mpi-selector-menu.

Note that when upgrading to this release's version of openmpi, you should migrate any default parameters set for lam or openmpi to /usr/lib(64)/lam/etc/ and /usr/lib(64)/openmpi/[openmpi version]-[compiler name]/etc/. All configurations for either openmpi or lam should be set in these directories.

lvm2 Snapshot Volume Warning

lvm2 will now warn if a snapshot volume is near its maximum capacity. However, this feature is not enabled by default.

To enable this feature, uncomment the following line in /etc/lvm/lvm.conf

snapshot_library = ""

Ensure that the dmeventd section and its delimiters ({ }) are also uncommented.


bash has been updated to version 3.2. This version fixes a number of outstanding bugs, most notably:

  • bash man page: updated to reflect the correct behavior of special built-in commands (such as eval, exec, and set. In addition, the bash man page now includes an explanation of the use of aliases in non-interactive scripts.

  • File descriptors now work as expected; in previous releases, bash did not close file descriptors with two or more digits.

  • A bug in the way bash handled certain multi-byte strings is now fixed.

Note that with this update, the output of ulimit -a has also changed from the Red Hat Enterprise Linux 5.1 version. This may cause a problems with some automated scripts. If you have any scripts that use ulimit -a output strings, you should revise them accordingly.

4. Driver Updates

General Driver/Platform Updates
  • Added the necessary PCI IDs to support the Intel E7221 Graphic Controller.

  • Added the necessary sub-device IDs to support the PCI-Express icom WAN adapter.

  • i2c-piix4 kernel module is now enabled to support the AMD SBX00 SMBus.

  • The following kernel configuration flags are now enabled to enhance kernel panic handling for Intelligent Platform Management Interface (IPMI):

    • CONFIG_IPMI_PANIC_EVENT — when a panic occurs, the IPMI message handler generates an IPMI event describing the panic to each interface registered with the message handler.

    • CONFIG_IPMI_PANIC_STRING — when a panic occurs, OEM events containing the panic string are generated.

    In addition to this, IPMI now supports the IBM Bladecenter QS21 and QS22.

  • The tlclk driver is now included to support the Intel MPCBL0050 systems.

  • All PCI-X configuration registers (up to 4096 bytes) are now accessible.

  • The maximum length of the kernel command line is now 2,048 bytes. To use this increased maximum length, upgrade the grub package.

  • IntelDynamic Acceleration Technology is now supported on Intel Core 2 Duo mobile processors. This allows a core to run at a higher-than-normal frequency when all CPUs (as a whole) are operating below maximum power.

  • The following chipsets are now supported through the EDAC driver:

    • Intel 3000

    • Intel 3010

    • Intel 5000 (Greencreek/Blackford)

  • The Intel Tolapai chipset (SATA, I2C) is now supported.

  • ioatdma: Added the necessary PCI IDs to support the DMA engine used in Unisys ES7000 systems.

  • High-Definition Multimedia Interface (HDMI) audio is now supported on AMD ATI integrated chipsets.

  • The Intel Xorg driver now provides enhanced support for i915 (and later) chips. This driver is also the default driver now for such chips. If you prefer to use the older Xorg driver (originally used for i810 chips), replace Intel with i810 in the Driver line of /etc/X11/xorg.conf (under the "Device" section).

    Basic runtime multi-head support is provided by the intel Xorg driver. Selecting a resolution with the System => Preferences => Screen Resolution tool (gnome-display-properties) will set that resolution on all connected outputs.

    Video hotkey support (Fn+F7 on most laptops) in the "intel" Xorg driver will scan all output connectors (including ports for the built-in flat panel on laptops) to determine which of them have monitors attached. All connected output ports will then be enabled.

  • The Sony/Philips Digital Interconnect Format (S/PDIF) port on the Dell D/Dock Expansion Station is now supported by the Dell M4300 and M6300 Precision Workstations. This allows digital audio output through the S/PDIF port on the Dell D/Dock Expansion Station when either the M4300 or M6300 is docked.

  • bnx2x: driver added to provide support for bcm5710 hardware.

  • tg3: updated to version 3.86. This update enables support for BroadCom 5761 and 5784 devices.

  • sierra: updated to version 1.0.5. This update enables support for additional variants of Sierra Wireless MC8755 and MC8775 chipsets.

  • In this release, the Intel 8254082547 network cards are supported by the e1000 driver, while the following network cards are supported by the e1000e driver:

    • Intel 8257182573

    • Intel 82562

    • Intel 82566

    • Intel 80003eslan

    In Red Hat Enterprise Linux 5.1, the e1000 driver supported all the aforementioned network cards.

    If your system contains a combination of both types of network cards, ethernet devices may be enumerated in a different order in this release. You may need to modify your network configuration after installation in order to remap each card's hardware address to specific device names if you need to preserve a particular order.

    Note that properly configured systems should not have device names changed on upgrade. To ensure this, the network configuration files (/etc/sysconfig/network-scripts/ifcfg-[device name]) should contain the HWADDR parameter, binding the device name to a specific hardware address.

  • lpfc: updated to version This update applies several devloss fixes, and enables support for the following:

    • 1, 2, 4, and 8GB auto-rate negotiation.

    • FC-SP DH-CHAP Authentication.

    • The latest HBAnyware configuration utility, which is also part of the driver master kit. This enables GUI-based driver configuration (including fibre channel and TCP/IP remote storage area network management), diagnostics (loopback and diagnostics dump) and FC-SP/Authentication Diffie-Hellman CHAP (DH-CHAP).

    • LPe1250, LPe1252, LPe12000 and LPe12002 (2, 4, and 8Gb capable HBAs).

    • NPIV virtual ports.

  • megaraid_sas: updated to version 3.15. This applies several upstream changes, most notably:

    • Added the following module parameters:

      • fast_load: enables the driver to load faster by skipping physical device check.

      • cmd_per_lun: sets the maximum number of commands per logical unit.

      • max_sectors: sets the maximum number of sectors per I/O command.

      • poll_mode_io: enables support for polling (i.e. reduced interrupt operations). When poll_mode_io is set, commands will also be completed from the I/O path.

    • Added support for hibernation.

    • SYNCHRONIZE_CACHE is now blocked by the driver.

  • aacraid: updated to version 1.1.5-2453. This applies several upstream changes, most notably:

    • Fixed a bug that caused aacraid to use an incorrect dma mapping mask during firmware assert recovery.

    • Added the capability to issue a hardware reset to the adapter via sysfs. In line with this, the following check features were also added:

      • check_interval — for checking adapter health

      • update_interval — for revising time intervals used by adapter

      • check_reset — for blocking adapter checks/resets

    • Added a SYNCHRONIZE_CACHE call to implement a more effective cache flushing schedule. This helps reduce application stalls resulting from multiple applications issuing I/O commands to the storage device.

    • Replaced all if/else packet formations with platform function calls.

    • VPD inquiry pages are now supported. This ensures that when an array is created, the metadata stored on the physical device is issued a unique serial number. This serial number remains constant throughout array morphing or migration to other controllers.

  • qla2xxx: updated to version 8.02.00-k5. This update to qla2xxx adds support for the following:

    • EHAFT, a QLogic host bus adapter mechanism that provides activity information about fibre channel devices.

    • N_Port ID Virtualization (NPIV), which allows multiple N_Port IDs to share a single physical N_Port. This allows you to tie virtualized guests to fibre-channel identifiers, allowing those guests to migrate between hosts while retaining their access in the storage area network.

    • 8GB fibre-channel devices.

    This update also applies several improvements provided from upstream.

  • mpt fusion: updated to version 3.04.05. This update provides several changes, most notably:

    • On-the-fly logging (via the sysfsshost attribute) is now supported.

    • Added new sysfsshost attributes that provide the following:

      • board_name

      • board_assembly

      • board_tracer

      • unique_id

      • version_bios

      • version_fw

      • version_product

      • version_mpi

      • version_nvdata_default

      • version_nvdata_persistent

      • debug_level

      • io_delay

      • device_delay

    • task_abort calls are no longer sent to hidden RAID components and volumes.

    • Changes related to fibre channel:

      • Brocade, a rebranded FC949E fibre channel controller, is now supported.

      • Link speeds are now displayed when the driver is loaded and whenever the link speed changes.

      • High-priority request queueing is now used instead of the handshake/doorbell system when sending management requests for SAS or fibre channel.

    • Changes related to parallel SCSI:

      • ATTO UL4D, a rebranded SPI 1030 controller, is now supported.

      • mptspi_target_destroy is now declared as static.

5. Kernel-Related Updates

This release applies following kernel bug fixes:

  • Executing binaries with more than 2GB of debug information no longer fails.

  • When shutting down a database, all allocated hugepages are now released upon shutdown.

  • invalidate_mapping_pages() calls no longer cause soft lockups.

  • A bug that delayed oomkill from launching in a timely fashion (on systems with large memory) is now fixed.

  • A bug that caused soft lockup warnings when allocating memory on a system with large memory is now fixed.

  • 32-bit NFS clients can now correctly process 64-bit inode numbers.

  • The kernel now asserts Data Terminal Ready (DTR) signals before printing to serial ports during boot time. DTR assertion is required by some devices. Kernel boot messages are now printed to serial consoles on such devices.

  • The kernel parameter ide0=noprobe no longer causes a kernel panic.

This kernel update also features the following enhancements:

  • Added a new kernel parameter: /proc/sys/vm/flush_mmap_pages. This parameter specifies whether or not memory-mapped file pages should be flushed to disk by kupdate while the memory map is active. Valid values for this parameter are 1 (enable memory mapping by kupdate) and 0 (disable memory mapping by kupdate). The default value for this parameter is 1.

    To configure this parameter, use echo [1 or 0] /proc/sys/vm/flush_mmap_pages. Setting this parameter to 0 does the following:

    • kupdate will not flush dirty memory-mapped file pages as long as the memory map is active.

    • All dirty file pages will be asynchronously flushed to disk only as soon as the memory map is deactivated.

    If you set /proc/sys/vm/flush_mmap_pages to 0, it is advisable that you use another application to manually sync memory-mapped pages to disk.

  • Added a new kernel parameter: /proc/sys/kernel/sched_interactivity. This parameter allows you to tune the CPU scheduler's interactivity estimator. The interactivity estimator allows interactive processes to acquire more CPU time without causing CPU starvation in other processes.

    To configure this parameter, use echo [interactivity_level] > /proc/sys/kernel/sched_interactivity, where [interactivity_level] can be any of the following:

    • 2 — interactivity estimator is fully activated.

    • 1 — provides a weaker affinity to interactive processes than 2, but avoids CPU starvation under certain scheduling patterns.

    • 0 — any bias or affinity towards interactive processes is disabled.

  • kprobe now supports kretprobe_blacklist[].

  • Core dump masking is now supported. This allows a core dump process to skip the shared memory segments of a process when creating a core dump file. This feature also allows you to select whether or not to dump anonymous shared memory for each process.

    When a process is dumped, all anonymous memory is written to a core file as long as the size of the core file isn't limited. In some cases, you may want to prevent some memory segments (such as huge shared memory) from being dumped. Conversely, you may also want to save file-backed memory segments into a core file, in addition to individual files.

    For these purposes, you can use /proc/[pid]/coredump_filter to specify which memory segments of the [pid] process is dumped. coredump_filter is a bitmask of memory types. If a bitmask is set, memory segments of the corresponding memory type are dumped.

    The following memory types are supported:

    • 0x0 — anonymous private memory

    • 0x1 — anonymous shared memory

    • 0x2 — file-backed private memory

    • 0x3 — file-backed shared memory

    To set a bitmask for [pid], simply echo the corresponding bitmask to /proc/[pid]/coredump_filter. For example, to prevent a dump of all shared memory segments attached to process 1111, use:

    echo 0x1 > /proc/1111/coredump_filter

    The default value of coredump_filter is 0x3, which specifies that all anonymous memory segments are dumped. Also, note that regardless of the bitmask status, MMIO pages (such as frame buffers) are never dumped and vDSO pages are always dumped

    When a new process is created, the process inherits the bitmask status from its parent. As such, Red Hat recommends that you set up coredump_filter before the program runs. To do so, echo the desired bitmask to /proc/self/coredump_filter before running the program.

  • audit can now trace and display per-session user activity.

  • REV UDF file sizes larger than 1GB are now supported.

  • Lock contention tracing and lockdep are now supported. These features provide in-depth information about spinlocks held in the kernel, which in turn help developers in driver debugging.

In addition to these, this release also features the following kernel updates:

  • The enumeration order of PCI devices has changed on several platforms to have NICs appear in the order they are labeled on the chassis and how the BIOS numbers them. The affected platforms are as follows:

    • Dell PowerEdge R900

    • HP ProLiant DL385 G2

    • HP ProLiant DL585 G2

    • HP Proliant DL580 G5

    Note that this change affects new installations only. If you prefer the old enumeration order, use the kernel parameter pci=nobfsort.

  • You can now determine the resource limit (rlimit) of a process. To do so, run cat /proc/[pid]/limits.

  • The maximum soft lockup timeout is now increased from 60 seconds to 300 seconds for systems that have a large number of CPUs. A soft lockup occurs when a CPU reports a memory starvation while it is unable to access a memory node accessed by other CPUs.

    In this release, you can also adjust the trigger limit for soft lockup warnings. To do so, use the following command (as root):

    echo [time] > /proc/sys/kernel/softlockup_thresh

    Replace [time] with the desired number of seconds before a soft lockup warning should be triggered. By default, this value is set to 10 (seconds).

  • show_mem() output now includes the total number of pagecache pages.

  • MSI-X is no longer enabled by default. To enable MSI-X, use the kernel module parameter ql2xenablemsix.

6. Virtualization

This section contains information about updates made to Red Hat Enterprise Linux suite of Virtualization tools.

  • Running 16 cores or more using AMD Rev F processors no longer results in system resets when performing fully-virtualized guest installations.

  • On an AMD NPT system used as a PAE host, guests can now have more than 4GB of memory.

    Note that nested paging can only translate 32-bit guest virtual addresses. This is because of a hardware feature that exists only in 32-bit physical address extensions (PAE).

  • When entering the second stage of a Windows™ Server 2003 installation, you no longer need to manually edit /etc/xen/[name of guest machine] to continue. The current user interface now allows you to change media on CD-ROMs attached to the guest.

  • The Virtual Machine Manager (virt-manager) included in this release now allows users to specify kernel boot parameters to the paravirtualized guest installer.

  • During the lifetime of dom0, you can now create guests (i.e. xm create) more than 32,750 times.

  • When using virt-manager to add disks to an existing guest, duplicate entries are no longer created in the guest's /etc/xen/[domain name] configuration file.

Known Issues
  • Paravirtualized guests can only have a maximum of 16 disk devices.

  • Migrating paravirtualized guests through xm migrate [domain][dom0 IP address] does not work.

  • Repeated live migration of paravirtualized guests between two hosts may cause one host to panic. If a host is rebooted after migrating a guest out of the system and before migrating the same guest back, the panic will not occur.

  • When installing Red Hat Enterprise Linux 5 on a fully virtualized SMP guest, the installation may freeze. This can occur when the host (dom0) is running Red Hat Enterprise Linux 5.2.

    To prevent this, set the guest to use a single processor using the install. You can do this by using the --vcpus=1 option in virt-install. Once the installation is completed, you can set the guest to SMP by modifying the allocated vcpus in virt-manager.

  • If a system configured for kdump encounters a kernel panic while an IDE device is performing I/O, the system may be unable to successfully boot into the kdump environment. This occurs if the IDE device is controlled by a device driver other than libata, and is caused by a bug in the IDE/ATA driver stack.

    To work around this, use the kdump command-line argument hd[X]=noprobe for storage devices and hd[X]=cdrom for optical drives, where [X] is the device identifier. Either command-line argument should be added to KDUMP_COMMANDLINE_APPEND in /etc/sysconfig/kdump.

7. Technology Previews

Technology Preview features are currently not supported under Red Hat Enterprise Linux subscription services, may not be functionally complete, and are generally not suitable for production use. However, these features are included as a customer convenience and to provide the feature with wider exposure.

Customers may find these features useful in a non-production environment. Customers are also free to provide feedback and functionality suggestions for a Technology Preview feature before it becomes fully supported. Erratas will be provided for high-severity security issues.

During the development of a Technology Preview feature, additional components may become available to the public for testing. It is the intention of Red Hat to fully support Technology Preview features in a future release.

ALUA Mode on EMC Clariion

Explicit active-passive failover (ALUA) mode using dm-multipath on EMC Clariion storage is now available. This mode is provided as per T10 specifications, but is provided in this release only as a technology preview.

For more information about T10, refer to


The radeon_tp driver is now included in this release as a Technology Preview. This driver enables the ATI R500/R600 chipsets.

This driver also features the following capabilities:

  • Modesetting on R500/R600 chipsets

  • 2D acceleration on R500 chipsets

  • Shadow framebuffer acceleration on R600 chipsets


FreeIPMI is now included in this update as a Technology Preview. FreeIPMI is a collection of Intelligent Platform Management IPMI system software. It provides in-band and out-of-band software, along with a development library conforming to the Intelligent Platform Management Interface (IPMI v1.5 and v2.0) standards.

For more information about FreeIPMI, refer to


The goal of the frysk project is to create an intelligent, distributed, always-on system monitoring and debugging tool that allows developers and system administrators to:

  • monitor running processes and threads (including creation and destruction events)

  • monitor the use of locking primitives

  • expose deadlocks

  • gather data

  • debug any given process by choosing it from a list or allowing frysk to open a source code (or other) window on a process that is crashing or misbehaving

This updated version of frysk includes the following new utilities:

  • fauxv

  • fdebuginfo

  • fdebugrpm

  • ferror

  • fexe

  • fmaps

In addition, ftrace can now perform signal and function symbol tracing. In previous releases, ftrace could only perform system call tracing.

frysk was introduced in Red Hat Enterprise Linux 5, and is still included in this release as a Technology Preview. For more information about frysk, refer to

TrouSerS and tpm-tools

TrouSerS and tpm-tools are included in this release to enable use of Trusted Platform Module (TPM) hardware.TPM hardware features include (among others):

  • Creation, storage, and use of RSA keys securely (without being exposed in memory)

  • Verification of a platform's software state using cryptographic hashes

TrouSerS is an implementation of the Trusted Computing Group's Software Stack (TSS) specification. You can use TrouSerS to write applications that make use of TPM hardware. tpm-tools is a suite of tools used to manage and utilize TPM hardware.

For more information about TrouSerS, refer to


eCryptfs is a stacked cryptographic file system for Linux. It mounts on individual directories in existing mounted lower file systems such as EXT3; there is no need to change existing partitions or file systems in order to start using eCryptfs.

eCryptfs stores cryptographic metadata in the header of each file written to the lower file system. This enables you to copy encrypted files between hosts or directly onto backup media. Files encrypted and copied in this manner can be decrypted with the proper key.

This release's version of eCryptfs provides several key management options, including protection based on passphrases and public keys. Below is a list of other fully functional features:

  • Interactive and non-interactive mounting.

  • Compatibility with SELinux.

  • Cryptographic metadata storage in both xattrs and file headers.

At present, the following issues still exist with eCryptfs:

  • direct_IO is not implemented.

  • Complex I/O patterns within the mmap implementation in eCryptfs may cause data corruption in some cases.

  • eCryptfs cannot be used for root file systems.

For more information about eCryptfs, refer to You can also refer to and for basic setup information.


GFS2 is an incremental advancement of GFS. This update applies several significant improvements that require a change to the on-disk file system format. GFS file systems can be converted to GFS2 using the utility gfs2_convert, which updates the metadata of a GFS file system accordingly.

While much improved since its introduction in Red Hat Enterprise Linux 5, GFS2 remains a Technology Preview. Benchmark tests indicate faster performance on the following:

  • heavy usage in a single directory and faster directory scans (Postmark benchmark)

  • synchronous I/O operations (fstest benchmark test indicates improved performance for messaging applications like TIBCO)

  • cached reads, as there is no longer any locking overhead

  • direct I/O to preallocated files

  • NFS file handle lookups

  • df, as allocation information is now cached

In addition, GFS2 also features the following changes:

  • journals are now plain (though hidden) files instead of metadata. Journals can now be dynamically added as additional servers mount a file system.

  • quotas are now enabled and disabled by the mount option quota=<on|off|account>

  • quiesce is no longer needed on a cluster to replay journals for failure recovery

  • nanosecond timestamps are now supported

  • similar to ext3, GFS2 now supports the data=ordered mode

  • attribute settings lsattr() and chattr() are now supported via standard ioctl()

  • file system sizes above 16TB are now supported

  • GFS2 is a standard file system, and can be used in non-clustered configurations

Stateless Linux

Stateless Linux is a new way of thinking about how a system should be run and managed, designed to simplify provisioning and management of large numbers of systems by making them easily replaceable. This is accomplished primarily 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 (refer to /etc/sysconfig/readonly-root for more details).

In its current state of development, the Stateless features are subsets of the intended goals. As such, the capability remains as Technology Preview.

Red Hat recommends that those interested in testing stateless code read the HOWTO at and join

The enabling infrastructure pieces for Stateless Linux were originally introduced in Red Hat Enterprise Linux 5.


AIGLX is a Technology Preview feature of the otherwise fully supported X server. It aims to enable GL-accelerated effects on a standard desktop. The project consists of the following:

  • A lightly modified X server.

  • An updated Mesa package that adds new protocol support.

By installing these components, you can have GL-accelerated effects on your desktop with very few changes, as well as the ability to enable and disable them at will without replacing your X server. AIGLX also enables remote GLX applications to take advantage of hardware GLX acceleration.

mac80211 802.11a/b/g WiFi protocol stack (mac80211)

The mac80211 stack (formerly known as the devicescape/d80211 stack) enables the iwlwifi 4965GN wireless driver for Intel Wifi Link 4965 hardware. This stack allows certain wireless devices to connect to any Wi-Fi network.

Although the stack is already accepted upstream, the stability of this stack is yet to be verified through testing. As such, this stack is included in this release as a Technology Preview.

iSCSI Target

The Linux target (tgt) framework allows a system to serve block-level SCSI storage to other systems that have a SCSI initiator. This capability is being initially deployed as a Linux iSCSI target, serving storage over a network to any iSCSI initiator.

To set up the iSCSI target, install the scsi-target-utils RPM and refer to the instructions in:

  • /usr/share/doc/scsi-target-utils-[version]/README

  • /usr/share/doc/scsi-target-utils-[version]/README.iscsi

Replace [version] with the corresponding version of the package installed.

For more information, refer to man tgtadm.


The firewire-sbp2 module is still included in this update as a Technology Preview. This module enables connectivity with FireWire storage devices and scanners.

At present, FireWire does not support the following:

  • IPv4

  • pcilynx host controllers

  • multi-LUN storage devices

  • non-exclusive access to storage devices

In addition, the following issues still exist in FireWire:

  • a memory leak in the SBP2 driver may cause the machine to become unresponsive.

  • a code in this version does not work properly in big-endian machines. This could lead to unexpected behavior in PowerPC.

8. Resolved Issues

  • Netapp devices can now complete failback (after a previously-failed path is restored) within a reasonable time with the default dm-multipath configuration.

  • system-config-kickstart now supports package selection through the Red Hat Network plugin.

  • kudzu can now properly parse ifcfg-* files that contain quotes around the HWADDR or SUBCHANNELS parameters. In addition, if a device's HWADDR is not specified, kudzu no longer modifies network configurations when the device is changed.

  • Running netstat with the -A inet or -A inet6 option (on a system where sctp was not added to the kernel) no longer terminates abnormally. Note, however, that netstat will display the following warning message when invoked with the -s option:

    netstat: no support for `AF INET (sctp)' on this system.
  • The nohide export option is no longer required on referral exports (i.e. exports that specify a referral server). For more information on bound mounts, refer to man 5 exports.

  • The priority callouts of dm-multipath are now statically compiled and copied onto the memory of multipathd. As such, multipathd no longer requires access to the root file system in order to execute priority callouts.

    This fixes a problem that occurred when running dm-multipath on devices containing the root file system, which caused such devices to freeze during fibre-channel path faults.

  • parted can now understand and correctly print out Xen Virtual Device (XVD) partition labels. This allows paravirtualized guests to use the parted utility. It is no longer necessary to run parted within dom0 to configure disk partitions on paravirtualized guests.

  • When upgrading to Red Hat Enterprise Linux 5.2 via Red Hat Network, you no longer need to manually import the redhat-beta key prior to upgrading.

  • Systems using the AMD 8132 or HT 1000 chipsets no longer need the pci=nommconf kernel parameter.

    Note that the system will still restrict such bridges to using the PortIO CF8/CFC mechanism. However, bridges (including those on the same platform) that respond correctly to MMCONFIG cycles will use MMCONFIG, provided that the platform's BIOS correctly supports MMCONFIG.

    However, if you are installing Red Hat Enterprise Linux 5.2 on an HP DC7800, the kernel parameter, pci=nommconf, is still needed. This is because the HP DC7800 is not yet included in the MMCONF blacklist.

  • Previous versions of Red Hat Enterprise Linux 5 on HP BL860c blade systems could hang during the IP information request stage of installation. When this occurred, you were required to reboot and perform the installation with Ethernet autonegotiation disabled.

    Red Hat Enterprise Linux 5.2 includes a fix for this issue.

  • Gemalto 64K smart cards now use Chip/Smart Card Interface Devices-compliant (CCID-compliant) readers. Previously, this smart card used the built-in e-gate reader, which essentially meant that the card and reader were being inserted at the same time. As a result, coolkey did not consistently recognize Gemalto 64K smart cards.

    With this update, coolkey now works correctly with Gemalto 64k smart cards.

9. Known Issues

  • A bug in the updated /etc/udev/rules.d/50-udev.rules file prevents the creation of persistent names for tape devices with numbers higher than 9 in their names. For example, a persistent name will not be created for a tape device with a name of nst12.

    To work around this, add an asterisk (*) after each occurrence of the string nst[0-9] in /etc/udev/rules.d/50-udev.rules.

  • The smartctl tool cannot properly read SMART parameters from SATA devices.

  • A bug in previous versions of openmpi and lam may prevent you from upgrading these packages. This bug manifests in the following error (when attempting to upgrade openmpi or lam:

    error: %preun(openmpi-[version]) scriptlet failed, exit status 2

    As such, you need to manually remove older versions of openmpi and lam in order to install their latest versions. To do so, use the following rpm command:

    rpm -qa | grep '^openmpi-\|^lam-' | xargs rpm -e --noscripts --allmatches

  • Some controller names (specifically, newer ones) printed by the cciss driver are incorrect, and will not match correctly with the names listed in the HP documentation. The cciss firmware, however, will be able to correctly print the names of each attached controller at boot-time.

  • When using dm-multipath, if features "1 queue_if_no_path" is specified in /etc/multipath.conf then any process that issues I/O will hang until one or more paths are restored.

    To avoid this, set no_path_retry [N] in /etc/multipath.conf (where [N] is the number of times the system should retry a path). When you do, remove the features "1 queue_if_no_path" option from /etc/multipath.conf as well.

  • Enabling multiple installed versions of the same kernel module is not supported. In addition to this, a bug in the way kernel module versions are parsed can sometimes result in enabling an older version of the same kernel module.

    Red Hat recommends that when you install a newer version of an installed kernel module, you should delete the older one first.

  • Executing kdump on an IBM Bladecenter QS21 or QS22 configured with NFS root will fail. To avoid this, specify an NFS dump target in /etc/kdump.conf.

  • IBM T60 laptops will power off completely when suspended and plugged into a docking station. To avoid this, boot the system with the argument acpi_sleep=s3_bios.

  • The QLogic iSCSI Expansion Card for the IBM Bladecenter provides both ethernet and iSCSI functions. Some parts on the card are shared by both functions. However, the current qla3xxx and qla4xxx drivers support ethernet and iSCSI functions individually. Both drivers do not support the use of ethernet and iSCSI functions simultaneously.

    Because of this limitation, successive resets (via consecutive ifdown/ifup commands) may hang the device. To avoid this, allow a 10-second interval after an ifup before issuing an ifdown. Also, allow the same 10-second interval after an ifdown before issuing an ifup. This interval allows ample time to stabilize and re-initialize all functions when an ifup is issued.

  • Laptops equipped with the Cisco Aironet MPI-350 wireless may hang trying to get a DHCP address during any network-based installation using the wired ethernet port.

    To work around this, use local media for your installation. Alternatively, you can disable the wireless card in the laptop BIOS prior to installation (you can re-enable the wireless card after completing the installation).

  • Boot-time logging to /var/log/boot.log is not available in Red Hat Enterprise Linux 5.2.

  • The system may not successfully reboot into a kexec/kdump kernel if X is running and using a driver other than vesa. This problem only exists with ATI Rage XL graphics chipsets.

    If X is running on a system equipped with ATI Rage XL, ensure that it is using the vesa driver in order to successfully reboot into a kexec/kdump kernel.

  • When using Red Hat Enterprise Linux 5.2 on a machine with an nVidia CK804 chipset installed, the following kernel messages may appear:

    kernel: assign_interrupt_mode Found MSI capability
    kernel: pcie_portdrv_probe->Dev[005d:10de] has invalid IRQ. Check vendor BIOS

    These messages indicate that certain PCI-E ports are not requesting IRQs. They do not, however, affect the operation of the machine in any way.

  • Removable storage devices (such as CDs and DVDs) do not automatically mount when you are logged in as root. As such, you will need to manually mount the device through the graphical file manager.

    Alternatively, you can run the following command to mount a device to /media:

    mount /dev/[device name] /media
  • When a LUN is deleted on a configured storage system, the change is not reflected on the host. In such cases, lvm commands will hang indefinitely when dm-multipath is used, as the LUN has now become stale.

    To work around this, delete all device and mpath link entries in /etc/lvm/.cache specific to the stale LUN.

    To find out what these entries are, run the following command:

    ls -l /dev/mpath | grep [stale LUN]

    For example, if [stale LUN] is 3600d0230003414f30000203a7bc41a00, the following results may appear:

    lrwxrwxrwx 1 root root 7 Aug  2 10:33 /3600d0230003414f30000203a7bc41a00 -> ../dm-4
    lrwxrwxrwx 1 root root 7 Aug  2 10:33 /3600d0230003414f30000203a7bc41a00p1 -> ../dm-5

    This means that 3600d0230003414f30000203a7bc41a00 is mapped to two mpath links: dm-4 and dm-5.

    As such, the following lines should be deleted from /etc/lvm/.cache:

  • Running the multipath command with the -ll option can cause the command to hang if one of the paths is on a blocking device. Note that the driver does not fail a request after some time if the device does not respond.

    This is caused by the cleanup code, which waits until the path checker request either completes or fails. To display the current multipath state without hanging the command, use multipath -l instead.

  • The system may not successfully reboot into a kexec/kdump kernel if X is running and using a driver other than vesa. This problem only exists with ATI Rage XL graphics chipsets.

    If X is running on a system equipped with ATI Rage XL, ensure that it is using the vesa driver in order to successfully reboot into a kexec/kdump kernel.

  • When running the bare-metal (non-Virtualized) kernel, the X server may not be able to retrieve EDID information from the monitor. When this occurs, the graphics driver will be unable to display resolutions highers than 800x600.

    To work around this, add the following line to the ServerLayout section of /etc/X11/xorg.conf:

    Option "Int10Backend" "x86emu"
  • Upgrading pm-utils from a Red Hat Enterprise Linux 5.2 Beta version of pm-utils will fail, resulting in the following error:

    error: unpacking of archive failed on file /etc/pm/sleep.d: cpio: rename

    To prevent this from occurring, delete the /etc/pm/sleep.d/ directory prior to upgrading. If /etc/pm/sleep.d contains any files, move those files to /etc/pm/hooks/.

  • Hardware testing for the Mellanox MT25204 has revealed that an internal error occurs under certain high-load conditions. When the ib_mthca driver reports a catastrophic error on this hardware, it is usually related to an insufficient completion queue depth relative to the number of outstanding work requests generated by the user application.

    Although the driver will reset the hardware and recover from such an event, all existing connections at the time of the error will be lost. This generally results in a segmentation fault in the user application. Further, if opensm is running at the time the error occurs, then you need to manually restart it in order to resume proper operation.

  • Attempting to run sniff may result in an error. This is because some required packages are not installed with dogtail.

    To prevent this from occurring, install the following packages manually:

    • librsvg2

    • ghostscript-fonts

    • pygtk2-libglade

  • It is not possible to configure layer 2 through system-config-network-gui.