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4. Release Notes for ppc

  • 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
  • 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.
  • nfsroot is fully supported in this update. This allows users to run Red Hat Enterprise Linux 5.1 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:
    • Each client must have its own separate root file system over the NFS server. This restriction applies even when read-only root is in use.
    • 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.
    The release notes included in the distribution of Red Hat Enterprise Linux 5.1 contains outdated instructions on how to set up nfsroot. Refer to the following procedure on how to set up nfsroot. As always, this procedure assumes that your network device is eth0 and the associated network driver is tg3. You may need to adjust according to your system configuration:
    1. Create the initrd in your home directory using the following command:
      mkinitrd --with=tg3 --rootfs=nfs --net-dev=eth0 --rootdev=<nfs server ip>:/<path to nfsroot> ~/initrd-<kernel-version>.img <kernel-version>
      This initrd must be created using the Red Hat Enterprise Linux 5.1 kernel.
    2. Next, create a zImage.initrd image from the initrd generated earlier. zImage.initrd is a compressed kernel and initrd in one image. Use the following command:
      mkzimage /boot/vmlinuz-<kernel-version> /boot/config-<kernel-version> /boot/System.map-<kernel-version> ~/initrd-<kernel-version>.img /usr/share/ppc64-utils/zImage.stub ~/zImage.initrd-<kernel-version>
    3. Copy the created zImage.initrd-<kernel-version> to an exportable location on your tftp server.
    4. Ensure that the exported nfsroot file system on the nfs server contains the necessary binaries and modules. These binaries and modules must correspond to the version of the kernel used to create the initrd in the first step.
    5. Configure the DHCP server to point the client to the target zImage.initrd-<kernel-version>.
      To do this, add the following entries to the /etc/dhcpd.conf file of the DHCP server: 
      			next-server <tftp hostname/IP address>;
			filename "<tftp-path>/zImage.initrd";
      Note that <tftp-path> should specify the path to the zImage.initrd from within the tftp-exported directory. For example, if the absolute path to the zImage.initrd is /tftpboot/mykernels/zImage.initrd and /tftpboot/ is the tftp-exported directory, then <tftp-path> should be mykernels/zImage.initrd.
    6. Finally, set your system's boot configuration parameters to make it boot first from the network device (in this example, the network device is eth0).
    For more information about setting up a Red Hat Enterprise Linux 5.1 network installation for the BladeCenter QS21, refer to http://www-01.ibm.com/chips/techlib/techlib.nsf/products/Cell_Broadband_Engine.
  • 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.
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