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5.1 Release Notes

Red Hat Enterprise Linux 5

Release Notes for Red Hat Enterprise Linux 5.1

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Red Hat Enterprise Linux Documentation

Don Domingo

Engineering Services and Operations Content Services

Abstract

The Release Notes provide high-level coverage of the improvements and additions that have been implemented in Red Hat Enterprise Linux 5.1. For detailed documentation on all changes to Red Hat Enterprise Linux for the 5.1 update, refer to the Technical Notes.

1. Release Notes for x86

  • 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 5.1.
    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.
  • This release includes WBEMSMT, a suite of web-based applications that provides a user-friendly management interface for Samba and DNS. For more information about WBEMSMT, refer to http://sblim.wiki.sourceforge.net/.
  • Upgrading pm-utils from a Red Hat Enterprise Linux 5.1 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, you can 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 are lost at the time of the error. This generally results in a segmentation fault in the user application. Further, if opensm is running at the time the error occurs, then it will have to be manually restarted in order to resume proper operation.
  • Driver Update Disks now support Red Hat's Driver Update Program RPM-based packaging. If a driver disk uses the newer format, it is possible to include RPM packaged drivers that will be preserved across system updates.
    Please note that driver RPMs are copied only for the default kernel variant that is in use on the installed system. For example, installing a driver RPM on a system running the virtualized kernel will install the driver only for the virtualized kernel. The driver RPM will not be installed for any other installed kernel variant in the system.
    As such, on a system that has multiple kernel variants installed, you will need to boot the system on each kernel variant and install the driver RPM. For example, if your system has both bare-metal and virtualized kernels installed, boot your system using the bare-metal kernel and install the driver RPM. Then, reboot the system into the virtualized kernel and install the driver RPM again.
  • During the lifetime of dom0, you cannot create guests (i.e. xm create) more than 32,750 times. For example, if you have guests rebooting in a loop, dom0 will fail to boot any guest after rebooting guests a total of 32,750 times.
    If this event occurs, restart dom0
  • Using the divider command-line argument may not work properly in this architecture. This issue will be addressed in a future update of Red Hat Enterprise Linux 5.
  • The Red Hat Enterprise Linux 5.1 NFS server now supports referral exports. These exports are based on extensions to the NFSv4 protocol. Any NFS clients that do not support these extensions (namely, Red Hat Enterprise Linux releases prior to 5.1) will not be able to access these exports.
    As such, if an NFS client does not support these exports, any attempt to access these exports may fail with an I/O error. In some cases, depending on the client implementation, the failure may be more severe, including the possibility of a system crash.
    It is important that you take precautions to ensure that NFS referral exports are not accessed by clients that do not support them.
  • 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. The release notes included in the distribution incorrectly states that GFS2 is fully supported. Nevertheless, 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
  • Installing Red Hat Enterprise Linux 5.1 on HP BL860c blade systems may hang during the IP information request stage. This issue manifests when you have to select OK twice on the Configure TCP/IP screen.
    If this occurs, reboot and perform the installation with Ethernet autonegotiation disabled. To do this, use the parameter ethtool="autoneg=off" when booting from the installation media. Doing so does not affect the final installed system.
  • The nohide export option is required on referral exports (i.e. exports that specify a referral server). This is because referral exports need to "cross over" a bound mount point. The nohide export option is required for such a "cross over" to be successful.
    For more information on bound mounts, refer to man exports 5.
  • This update includes the lvm2 event monitoring daemon. If you are already using lvm2 mirroring, perform the following steps to ensure that all monitoring functions are upgraded properly:
    1. Deactivate all mirrored lvm2 logical volumes before updating. To do this, use the command lvchange -a n <volume group or mirrored volume>.
    2. Stop the old lvm2 event daemon using killall -HUP dmeventd.
    3. Perform the upgrade of all related RPM packages, namely device-mapper and lvm2.
    4. Reactivate all mirrored volumes again using lvchange -a y <volume group or mirrored volume>.
  • Rapid Virtualization Indexing (RVI) is now supported on 64-bit, 32-bit, and 32-bit PAE kernels. However, RVI can only translate 32-bit guest virtual addresses on the 32-bit PAE hypervisor.
    As such, if a guest is running a PAE kernel with more than 3840MB of RAM, a wrong address translation error will occur. This can crash the guest.
    It is recommended that you use the 64-bit kernel if you intend to run guests with more than 4GB of physical RAM under RVI.
  • Running 16 cores or more using AMD Rev F processors may result in system resets when performing fully-virtualized guest installations.
  • Installing the systemtap-runtime package will result in a transaction check error if the systemtap package is already installed. Further, upgrading Red Hat Enterprise Linux 5 to 5.1 will also fail if the systemtap package is already installed.
    As such, remove the systemtap package using the command rpm -e systemtap-0.5.12-1.e15 before installing systemtap-runtime or performing an upgrade.
  • When setting up NFSROOT, BOOTPROTO must be set as BOOTPROTO=dhcp in /etc/sysconfig/network-scripts/ifcfg-eth0.
    If your environment requires a different setting for BOOTPROTO, then temporarily set BOOTPROTO=dhcp in /etc/sysconfig/network-scripts/ifcfg-eth0 before initially creating the initrd. You can reset the original value of BOOTPROTO after the initrd is created.
  • Crash dumping through kexec and kdump may not function reliably with HP Smart Array controllers. Note that these controllers use the cciss driver.
    A solution to this problem, which is likely to involve a firmware update to the controller, is being investigated.
  • Creating a guest more than 1,000 times will cause dom0 to reboot suddenly. It is recommended that you pre-empt this by rebooting dom0 before the domain ID of any guest reaches 1,000.
  • 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.
    As such, using both ethernet and iSCSI functions simultaneously may hang the device. This could result in data loss and filesystem corruption on iSCSI devices, or network disruptions on other connected ethernet devices.
  • When using virt-manager to add disks to an existing guest, duplicate entries may be created in the guest's /etc/xen/<domain name> configuration file. These duplicate entries will prevent the guest from booting.
    As such, you should remove these duplicate entries.
  • Repeatedly migrating a guest 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.
  • sysreport is being deprecated in favor of sos. To install sos, run yum install sos. This command installs sos and removes sysreport. It is recommended that you update any existing kickstart files to reflect this.
    After installing sos, use the command sosreport to invoke it. Using the command sysreport generates a warning that sysreport is now deprecated; continuing will invoke sosreport.
    If you need to use the sysreport tool specifically, use the command sysreport.legacy to invoke it.
    For more information about sosreport, refer to man sosreport and sosreport --help.

1.2. Feature Updates

EXT3 Enhancement
The maximum capacity of the EXT3 is now 16TB (increased from 8TB). This enhancement was originally included in Red Hat Enterprise Linux 5 as a Technology Preview, and is now fully supported in this update.
yum-security
It is now possible to limit yum to install security updates only. To do so, simply install the yum-security plugin and run the following command:
yum update --security
Restarting a Resource Independently
It is now possible to restart a resource in a cluster without interrupting its parent service. This can be configured in /etc/cluster/cluster.conf on a running node using the __independent_subtree="1" attribute to tag a resource as independent.
For example: 
<service name="example">
        <fs name="One" __independent_subtree="1" ...>
                <nfsexport ...>
                        <nfsclient .../>
                </nfsexport>
        </fs>
        <fs name="Two" ...>
                <nfsexport ...>
                        <nfsclient .../>
                </nfsexport>
                <script name="Database" .../>
        </fs>
        <ip/>
</service>
Here, two file system resources are used: One and Two. If One fails, it is restarted without interrupting Two. If Two fails, all components (One, children of One and children of Two) are restarted. At no given time are Two and its children dependent on any resource provided by One.
Note that Samba requires a specific service structure, and as such it cannot be used in a service with independent subtrees. This is also true for several other resources, so use the __independent_subtree="1" attribute with caution.
Virtualization
The following Virtualization updates are also included in this release:
  • The virtualized kernel can now use the kdump function.
  • AMD-V is now supported in this release. This enables live domain migration for fully virtualized guests.
  • The virtualized kernel can now support up to 16GB of RAM.
  • The virtualized kernel can now support up to 256GB of RAM.
  • The in-kernel socket API is now expanded. This was done to fix a bug that occurs when running sctp between guests.
  • Virtual networking is now part of libvirt, the virtualization library. libvirt has a set of commands that sets up a virtual NAT/router and private network for all local guests on a machine. This is especially useful for guests that do not need to be routable from the outside. It is also useful for developers who use Virtualization on laptops.
    Note that the virtual networking capability adds a dependency on dnsmasq, which handles dhcp for the virtual network.
    For more information about libvirt, refer to http://libvirt.org.
  • libvirt can now manage inactive virtual machines. libvirt does this by defining and undefining domains without stopping or starting them. This functionality is similar to the virsh define and virsh undefine commands.
    This enhancement allows the Red Hat Virtual Machine Manager to display all available guests. This allows you to start these guests directly from the GUI.
  • Installing the kernel-xen package no longer leads to the creation of incorrect / incomplete elilo.conf entries.
  • Fully virtualized guests now support live migration.
  • The xm create command now has a graphical equivalent in virt-manager.
  • Nested Paging (NP) is now supported. This feature reduces the complexity of memory management in virtualized environments. In addition, NP also reduces CPU utilization in memory-intensive guests.
    At present, NP is not enabled by default. If your system supports NP, it is recommended that you enable NP by booting the hypervisor with the parameter hap=1.
This update to the Virtualization feature also includes the capability to install and run paravirtualized 32-bit guests on 64-bit hosts. However, this capability is provided as a Technology Preview; as such, it is not supported for production use.
Shared Page Tables
Shared page tables are now supported for hugetlb memory. This enables page table entries to be shared among multiple processes.
Sharing page table entries among multiple processes consumes less cache space. This improves application cache hit ratio, resulting in better application performance.
divider
The divider=<value> option is a kernel command-line parameter that allows you to adjust the system clock rate while maintaining the same visible HZ timing value to user space applications.
Using the divider= option allows you to reduce CPU overhead and increase efficiency at the cost of lowering the accuracy of timing operations and profiling. This is useful in virtualized environments as well as for certain applications.
Useful <values> for the standard 1000Hz clock are:
  • 2 = 500Hz
  • 4 = 250Hz
  • 10 = 100Hz (value used by previous releases of Red Hat Enterprise Linux)
Note that the virtualized kernel uses a 250HZ clock by defaul. As such, it does not need the divider= option either in dom0 or in paravirtualized guests.
Installing to dm-multipath Devices
Anaconda now has the capability to detect, create, and install to dm-multipath devices. To enable this feature, add the parameter mpath to the kernel boot line.
This feature was originally introduced in Red Hat Enterprise Linux 5 as a Technology Preview, and is now fully supported in this release.
Note that dm-multipath also features inbox support for the Dell MD3000. However, multiple nodes that use dm-multipath to access the MD3000 cannot perform immediate failback.
Further, it is recommended that you use the Custom Partitioning interface in Anaconda if your system has both multipath and non-multipath devices. Using Automatic Partitioning in such cases may create both types of devices in the same logical volume groups.
At present, the following restrictions apply to this feature:
  • If there is only one path to the boot Logical Unit Number (LUN), Anaconda installs to the SCSI device even if mpath is specified. Even after you enable multiple paths to the boot LUN and recreate the initrd, the operating system will will boot from the SCSI device instead of the dm-multipath device.
    However, if there are multiple paths to the boot LUN to begin with, Anaconda will correctly install to the corresponding dm-multipath device after mpath is specified in the kernel boot line.
  • By default, user_friendly_names is set to yes in multipath.conf. This is a required setting in the support implementation of the dm-multipath root device. As such, setting user_friendly_names to no and recreating the initrd will result in a boot failure with the following error: 
    Checking filesystems
fsck.ext3: No such file or directory while trying to open /dev/mapper/mpath0p1
Booting from Storage Area Network (SAN)
The ability to boot from a SAN disk device is now supported. In this case, SAN refers to a Fibre Channel or iSCSI interface. This capability also features support for system-to-storage connection through multiple paths using dm-multipath.
In configurations that use multiple host bus adapters (HBA), you may need to set the system BIOS to boot from another adapter if all paths through the current adapter fail.
Driver Update Program
The Driver Update Program (DUP) was designed to allow third-party vendors (such as OEMs) to add their own device drivers and other Linux Kernel Modules to Red Hat Enterprise Linux 5 systems using regular RPM packages as the distribution containers.
Red Hat Enterprise Linux 5.1 applies several updates to the DUP, most notably:
  • install-time Driver Update RPMs through Driver Update Disks is now supported
  • bootpath Driver Updates affecting the system bootpath are now supported
  • support for third-party packaging of Advanced Linux Sound Architecture (ALSA) is now deprecated
Further, various updates were applied to the approved kernel ABI symbol whitelists. These whitelists are used by packaging drivers to determine which symbols and data structures provided by the kernel can be used in a third-party driver.
For more information, refer to http://www.kerneldrivers.org/RedHatKernelModulePackages.

1.3. Driver Updates

General Driver Updates
  • acpi: updated ibm_acpi module to address several ACPI and docking station issues with Lenovo laptops.
  • ipmi: Polling kthread no longer runs when hardware interrupt is assigned to a Baseboard Management Controller.
  • sata: SATA/SAS upgraded to version 2.6.22-rc3.
  • openib and openmpi: upgraded to OFED (OpenFabrics Enterprise Distribution) version 1.2.
  • powernow-k8: upgraded to version 2.0.0 to fully support Greyhound.
  • xinput: added to enable full RSA support.
  • aic94xx: upgraded to version 1.0.2-1, in line with an upgrade of the embedded sequencer firmware to v17. These updates apply the following changes:
    • fixed ascb race condition on platforms with expanders
    • added REQ_TASK_ABORT and DEVICE_RESET handlers
    • physical ports are now cleaned up properly after a discovery error
    • phys can now be enabled and disabled through sysfs
    • extended use of DDB lock to prevent race condition of DDB
Audio
ALSA updated to version 1.0.14. This update applies the following fixes:
  • fixed noise problem on the IBM Taroko (M50)
  • Realtek ALC861 is now supported
  • fixed a muting problem on xw8600 and xw6600
  • ADI 1884 Audio is now supported
  • fixed an audio configuration problem on xw4600
PCI
  • added function calls to set maximum read request size for PCIX and PCI-Express
  • IBM System P machines now support PCI-Express hotplugging
  • added necessary drivers and PCI ID to support SB600 SMBus
Network
  • e1000 driver: updated to version 7.3.20-k2 to support I/OAT-enabled chipsets.
  • bnx2 driver: updated to version 1.5.11 to support 5709 hardware.
  • B44 ethernet driver: backported from upstream version 2.6.22-rc4 to apply the following changes:
    • several endianness fixes were made
    • DMA_30BIT_MASK constant is now used
    • skb_copy_from_linear_data_offset() is now used
    • spin_lock_irqsave() now features safer interrupt disabling
    • simple error checking is performed during resume
    • several fixes to multicast were applied
    • chip reset now takes longer than previously anticipated
  • Marvell sky2 driver: updated to version 1.14 to fix a bug that causes a kernel panic if the ifup/ifdown commands are executed repeatedly.
  • forcedeth-0.60 driver: now included in this release. This applies several critical bug fixes for customers using NVIDIA's MCP55 motherboard chipsets and corresponding onboard NIC.
  • ixgb driver: updated to the latest upstream version (1.0.126).
  • netxen_nic driver: version 3.4.2-2 added to enable support for NetXen 10GbE network cards.
  • Chelsio 10G Ethernet Network Controller is now supported.
  • added support for PCI error recovery to the s2io device.
  • Broadcomm wireless ethernet driver now supports PCI ID for nx6325 card.
  • fixed a bug that caused an ASSERTION FAILED error when attempting to start a BCM4306 via ifup.
  • ixgb driver: updated to add EEH PCI error recovery support for the Intel 10-gigabit ethernet card. For more information, refer to /usr/share/doc/kernel-doc-<kernel version>/Documentation/pci-error-recovery.txt.
  • qla3xxx driver: re-enabled and updated to version 2.03.00-k3 to provide networking support for QLogic iSCSI adapters without using iSCSI.
  • Intel PRO/Wireless 3945ABG network driver: updated to version 1.2.0. This update resolves several issues, including a soft lockup bug that could occur under certain circumstances on some laptops.
  • qla2xxx: driver upgraded to version 8.01.07-k6. This applies several changes, most notably:
    • iIDMA is now supported
    • the following Fibre Channel attributes are now supported:
      • symbolic nodename
      • system hostname
      • fabric name
      • host port state
    • trace-control async events are no longer logged
    • reset handling logic has been corrected
    • MSI-X is now supported
    • IRQ-0 assignments are now handled per system
    • NVRAM updates immediately go into effect
IPMI
This release includes an update of the IPMI driver set to include the upstream changes as of version 2.6.21.3, with some patches included from 2.6.22-rc-4. This update features the following changes (among others):
  • fixed uninitialized data bug in ipmi_si_intf
  • kipmid is no longer started if another driver supports interrupts
  • users are now allowed to override the kernel daemon enable through force_kipmid
  • per-channel command registration is now supported
  • MAX_IPMI_INTERFACES is no longer used
  • hot system interface removal is now supported
  • added a Maintenance Mode to support firmware updates
  • added poweroff support for the pigeonpoint IPMC
  • BT subdriver can now survive long timeouts
  • added pci_remove handling for proper cleanup on a hot remove
For information about new module parameters, refer to /usr/share/doc/kernel-doc-<kernel version>/Documentation/IPMI.txt.
SCSI
  • ported SCSI blacklist from Red Hat Enterprise Linux 4 to this release.
  • added PCI IDs for aic79xx driver.
  • aacraid driver: updated to version 1.1.5-2437 to support PRIMERGY RX800S2 and RX800S3.
  • megaraid_sas driver: updated to version 3.10. This update defines the entry point for bios_param, adds an IOCTL memory pool, and applies several minor bug fixes.
  • Emulex lpfc driver: updated to version 8.1.10.9. This update applies several changes, most notably:
    • fixed host_lock management in the ioctl paths
    • the AMD chipset is now automatically detected, and reduced the DMA length to 1024 bytes
    • nodes are no longer removed during dev_loss_tmo if discovery is active
    • 8GB link speeds are now enabled
  • qla4xxx driver updated to apply the following changes:
    • added support for IPV6, QLE406x and ioctl module
    • fixed a mutex_lock bug that could cause lockups
    • resolved lockup issues of qla4xxx and qla3xxx when attempting to load/unload either interface
  • mpt fusion drivers: updated to version 3.04.04. This update applies several changes, most notably:
    • fixed several error handling bugs
    • mptsas now serializes target resets
    • mptsas and mptfc now support LUNs and targets greater than 255
    • fixed an LSI mptspi driver regression that resulted in extremely slow DVD driver performance
    • when an LSI SCSI device returns a BUSY status, I/O attempts no longer fail after several retries
    • RAID arrays are no longer unavailable after auto-rebuild
  • arcmsr driver: included to provide support for Areca RAID controllers.
  • 3w-9xxx module: updated to correctly support 3ware 9650SE.

1.5. Other Updates

  • gaim is now called pidgin.
  • Intel microcode updated to version 1.17. This adds support for new Intel processors.
  • Implicit active-active failover using dm-multipath on EMC Clariion storage is now supported.
  • The Chinese font Zysong is no longer installed as part of the fonts-chinese package. Zysong is now packaged separately as fonts-chinese-zysong. The fonts-chinese-zysong package is located in the Supplementary CD.
    Note that the fonts-chinese-zysong package is needed to support the Chinese National Standard GB18030.
  • The Challenge Handshake Authentication Protocol (CHAP) username and password have a character limit of 256 each.
  • pump is deprecated in this update. As such, configuring your network interface through netconfig may result in broken ifcfg scripts.
    To properly configure your network interface, use system-config-network instead. Installing the updated system-config-network package removes netconfig.
  • rpm --aid is no longer supported. It is recommended that you use yum when updating and installing packages.

1.6. Technology Previews

Technology Preview features are currently not supported under Red Hat Enterprise Linux 5.1 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.
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.
The following is a list of the initial capabilities included in Red Hat Enterprise Linux 5:
  • running a stateless image over NFS
  • running a stateless image via loopback over NFS
  • running on iSCSI
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.
The enabling infrastructure pieces for Stateless Linux were originally introduced in Red Hat Enterprise Linux 5.
AIGLX
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.
devicescape (d80211)
The devicescape stack enables the iwlwifi 4965GN wireless driver. This stack allows certain wireless devices to connect to any Wi-Fi network.
This stack has a code base that is yet to be accepted upstream. In addition, the stability of this stack is yet to be conclusively verified through testing. As such, this stack is included in this release as a Technology Preview.
FS-Cache
FS-Cache is a local caching facility for remote file systems that 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.
Systemtap
Systemtap provides free software (GPL) infrastructure to simplify the gathering of information about the running Linux system. This assists the diagnosis of a performance or functional problem. With the help of systemtap, developers no longer need to go through the tedious and disruptive instrument, recompile, install, and reboot sequence that may be otherwise required to collect data.
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.
FireWire
The firewire-sbp2 module is 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 this version of 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.

1.7. Resolved Issues

  • A SATA bug that caused SATA-equipped systems to pause during the boot process and display an error before resuming is now fixed.
  • In multi-boot systems, parted now preserves the starting sector of the first primary partition where Windows Vista™ is installed. As such, when setting up a multi-boot system with both Red Hat Enterprise Linux 5.1 and Windows Vista™, the latter is no longer rendered unbootable.
  • rmmod xennet no longer causes domU to crash.
  • 4-socket AMD Sun Blade X8400 Server Module systems that do not have memory configured in node 0 no longer panic during boot.
  • conga and luci can now be used to create and configure failover domains.
  • When installing the Cluster Storage group through yum, the transaction no longer fails.
  • During installation, incorrect SELinux contexts are no longer assigned to /var/log/faillog and /var/log/tallylog.
  • On the dual-core AMD Platform, cpu-intensive activity on a single cpu no longer causes CPU cores to change frequencies.
  • Installing Red Hat Enterprise Linux 5.1 using split installation media (for example, CD or NFSISO) no longer causes an error in the installation of amanda-server.
  • During the installation process, Anaconda can now detect more than 4GB of RAM. This allows Anaconda to automatically determine whether it needs to install the kernel-PAE variant of the kernel or not.
  • EDAC now reports the correct amount of memory on the latest k8 processors.
  • Logging in remotely to a Gnome desktop via gdm no longer causes the login screen to hang.
  • A bug in autofs that prevented multi-mounts from working properly is now fixed.
  • Running tvtime and xawtv with the bttv kernel module no longer causes the system to freeze.
  • Several patches to utrace apply the following fixes:
    • fixed a bug that causes a crash in race condition when using ptrace
    • fixed a regression that resulted in erroneous EIO returns from some PTRACE_PEEKUSR calls
    • fixed a regression that prevented some wait4 calls from waking up when a child exited under certain circumstances
    • fixed a regression that sometimes prevented SIGKILL from terminating a process. This occurred if ptrace was performed on a process under certain cirtumstances.
  • A RealTime Clock (RTC) bug that prevented alarms and periodic RTC interrupts from working properly is now fixed.

1.8. Known Issues

  • The first time the Release Notes button is clicked in Anaconda, a delay occurs while the window renders the Release Notes. During this delay, a seemingly empty list appears in the window. The rendering normally completes quickly, so most users may not notice this.
    This delay is mostly due to the fact that the package installation phase is the most CPU-intensive phase of installation.
  • Some machines that use NVIDIA graphics cards may display corrupted graphics or fonts when using the graphical installer or during a graphical login. To work around this, switch to a virtual console and back to the original X host.
  • Host bus adapters that use the MegaRAID driver must be set to operate in "Mass Storage" emulation mode, not in "I2O" emulation mode. To do this, perform the following steps:
    1. Enter the MegaRAID BIOS Set Up Utility.
    2. Enter the Adapter settings menu.
    3. Under Other Adapter Options, select Emulation and set it to Mass Storage.
    If the adapter is incorrectly set to "I2O" emulation, the system will attempt to load the i2o driver. This will fail, and prevent the proper driver from being loaded.
    Previous Red Hat Enterprise Linux releases generally do not attempt to load the I2O driver before the MegaRAID driver. Regardless of this, the hardware should always be set to "Mass Storage" emulation mode when used with Linux.
  • 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).
  • Currently, system-config-kickstart does not support package selection and deselection. When using system-config-kickstart, the Package Selection option indicates that it is disabled. This is because system-config-kickstart uses yum to gather group information, but is unable to configure yum to connect to Red Hat Network.
    At present, you need to update package sections in your kickstart files manually. When using system-config-kickstart to open a kickstart file, it will preserve all package information in it and write it back out when you save.
  • Boot-time logging to /var/log/boot.log is not available in this update of Red Hat Enterprise Linux 5. An equivalent functionality will be added in a future update.
  • When upgrading from Red Hat Enterprise Linux 4 to Red Hat Enterprise Linux 5, the Deployment Guide is not automatically installed. You need to use pirut to manually install it after completing the upgrade.
  • 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.
  • Installing the Virtualization feature may cause a time went backwards warning on HP systems with model numbers xw9300 and xw9400.
    To work around this issue for xw9400 machines, configure the BIOS settings to enable the HPET timer. Note that this option is not available on xw9300 machines.
    This will be resolved in an upcoming BIOS update by HP.
  • When using Red Hat Enterprise Linux 5 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. Further, these messages do not, in any way, affect the operation of the machine.
  • 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
  • The Calgary IOMMU chip is not supported by default in this update. To enable support for this chip, use the kernel command line option iommu=calgary.
  • The IBM System z does not provide a traditional Unix-style physical console. As such, Red Hat Enterprise Linux 5 for the IBM System z does not support the firstboot functionality during initial program load.
    To properly initialize setup for Red Hat Enterprise Linux 5 on the IBM System z, run the following commands after installation:
    • /usr/bin/setup — provided by the setuptool package.
    • /usr/bin/rhn_register — provided by the rhn-setup package.
  • When upgrading from Red Hat Enterprise Linux 5 to Red Hat Enterprise Linux 5.1 via Red Hat Network, yum may not prompt you to import the redhat-beta key. As such, it is advised that you import the redhat-beta key manually prior to upgrading. To do this, run the following command:
    rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-beta
  • When a LUN is deleted on a configured filer, 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: 
    /dev/dm-4 
/dev/dm-5 
/dev/mapper/3600d0230003414f30000203a7bc41a00
/dev/mapper/3600d0230003414f30000203a7bc41a00p1
/dev/mpath/3600d0230003414f30000203a7bc41a00
/dev/mpath/3600d0230003414f30000203a7bc41a00p1
  • When attempting to create a fully virtualized Windows™ guest from a CD or DVD, the second stage of the guest install might not continue upon reboot.
    To work around this, edit /etc/xen/<name of guest machine> by properly appending an entry for the CD / DVD device.
    If an installation to a simple file is used as a virtual device, the disk line of /etc/xen/<name of guest machine> will read like the following: 
    disk = [ 'file:/PATH-OF-SIMPLE-FILE,hda,w']
    A DVD-ROM device located on the host as /dev/dvd can be made available to stage 2 of the installation as hdc by appending an entry like 'phy:/dev/dvd,hdc:cdrom,r'. As such, the disk line should now read as follows: 
    disk = [ 'file:/opt/win2003-sp1-20061107,hda,w', 'phy:/dev/dvd,hdc:cdrom,r']
    The precise device path to use may vary depending on your hardware.
  • If the sctp module is not added to the kernel, running netstat with the -A inet or -A inet6 option abnormally terminates with the following message: 
    netstat: no support for `AF INET (sctp)' on this system.
    To avoid this, install the sctp kernel module.
  • Installing Red Hat Enterprise Linux 3.9 on a fully virtualized guest may be extremely slow. In addition, booting up the guest after installation may result in hda: lost interrupt errors.
    To avoid this bootup error, configure the guest to use the SMP kernel.
  • Current kernels do not assert Data Terminal Ready (DTR) signals before printing to serial ports during boot time. DTR assertion is required by some devices; as a result, kernel boot messages are not printed to serial consoles on such devices.
  • Upgrading a host (dom0) system to Red Hat Enterprise Linux 5.1 may render existing Red Hat Enterprise Linux 4.5 SMP paravirtualized guests unbootable. This is more likely to occur when the host system has more than 4GB of RAM.
    To work around this, boot each Red Hat Enterprise Linux 4.5 guest in single CPU mode and upgrade its kernel to the latest version (for Red Hat Enterprise Linux 4.5.z).
  • The AMD 8132 and HP BroadCom HT100 used on some platforms (such as the HP dc7700) do not support MMCONFIG cycles. If your system uses either chipset, your PCI configuration should use the legacy PortIO CF8/CFC mechanism. To configure this, boot the system with the kernel parameter -pci nommconfig during installation and add pci=nommconf to GRUB after rebooting.
    Further, the AMD 8132 chipset does not support Message Signaled Interrupts (MSI). If your system uses this chipset, you should also disable MSI. To do this, use the kernel parameter -pci nomsi during installation and add pci=nomsi to GRUB after rebooting.
    However, if your specific platform is already blacklisted by the kernel, your system does not require the aforementioned pci kernel parameters. The following HP platforms are already blacklisted by the kernel:
    • DL585g2
    • dc7500
    • xw9300
    • xw9400
  • 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"
  • The Virtual Machine Manager (virt-manager) included in this release does not allow users to specify additional boot arguments to the paravirtualized guest installer. This is true even when such arguments are required to install certain types of paravirtualized guests on specific types of hardware.
    This issue will be addressed in a future release of virt-manager. To specify arbitrary kernel arguments in installing paravirtualized guests from the command line, use virt-install.
  • With the default dm-multipath configuration, Netapp devices may take several minutes to complete failback after a previously failed path is restored. To resolve this problem, add the following Netapp device configuration to the devices section of the multipath.conf file: 
    devices {
        device {
                vendor                  "NETAPP"
                product                 "LUN"
                getuid_callout          "/sbin/scsi_id -g -u -s /block/%n"
                prio_callout            "/sbin/mpath_prio_netapp /dev/%n"
                features                "1 queue_if_no_path"
                hardware_handler        "0"
                path_grouping_policy    group_by_prio
                failback                immediate
                rr_weight               uniform
                rr_min_io               128
                path_checker            directio
        }
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