Oracle® Linux

Release Notes for Unbreakable Enterprise Kernel Release 3 Quarterly Update 5

E60671-01

March 2015

Abstract

This document contains information on Quarterly Update 5 to the Unbreakable Enterprise Kernel Release 3. This document may be updated after it is released. To check for updates to this document, and to view other Oracle documentation, refer to the Documentation section on the Oracle Technology Network (OTN) Web site:

http://www.oracle.com/technology/documentation/

This document is intended for users and administrators of Oracle Linux. It describes potential issues and the corresponding workarounds you may encounter while using the Unbreakable Enterprise Kernel Release 3 with Oracle Linux 6 or Oracle Linux 7. Oracle recommends that you read this document before installing or upgrading the Unbreakable Enterprise Kernel Release 3.

Document generated on: 2015-03-18 (revision: 2663)


Table of Contents

Preface
1 New Features and Changes
1.1 Notable Changes
1.2 Xen Improvements
1.3 Driver Updates
1.4 Technology Preview
1.4.1 Using the NFS over RDMA Client
1.5 Compatibility
1.6 Header Packages for Development
2 Fixed and Known Issues
2.1 Fixed Issues
2.2 Known Issues
3 Installation and Availability
3.1 Upgrading to the Latest UEK Release
3.2 Switching an Oracle Linux 6 System to UEK R3 (ULN)
3.3 Switching an Oracle Linux 6 System to UEK R3 (Public Yum)
A Legal Notices
A.1 Oracle Legal Notices
A.2 DocBook XSL License

Preface

The Oracle Linux Unbreakable Enterprise Kernel Release Notes provides a summary of the new features, changes, and fixed and known issues in the Unbreakable Enterprise Kernel Release 3.

Audience

This document is written for system administrators who want to use the Unbreakable Enterprise Kernel with Oracle Linux. It is assumed that readers have a general understanding of the Linux operating system.

Related Documents

The latest version of this document and other documentation for this product are available at:

http://www.oracle.com/technetwork/server-storage/linux/documentation/index.html.

Conventions

The following text conventions are used in this document:

Convention

Meaning

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Boldface type indicates graphical user interface elements associated with an action, or terms defined in text or the glossary.

italic

Italic type indicates book titles, emphasis, or placeholder variables for which you supply particular values.

monospace

Monospace type indicates commands within a paragraph, URLs, code in examples, text that appears on the screen, or text that you enter.

Chapter 1 New Features and Changes

The Unbreakable Enterprise Kernel Release 3 (UEK R3) is Oracle's third major release of its heavily tested and optimized operating system kernel for Oracle Linux 6 and 7 on the x86-64 architecture. It is based on the mainline Linux kernel version 3.8.13.

The 3.8.13-68 release is the fifth quarterly update release for UEK R3. It includes security and bug fixes, as well as driver updates.

Oracle actively monitors upstream checkins and applies critical bug and security fixes to UEK R3.

UEK R3 uses the same versioning model as the mainline Linux kernel version. It is possible that some applications might not understand the 3.x versioning scheme. If an application does require a 2.6 context, you can use the uname26 wrapper command to start it. However, regular Linux applications are usually neither aware of, nor affected by, Linux kernel version numbers.

1.1 Notable Changes

  • Update to the bonding driver to enable the ethtool command to show useful data about a bond, such as the link aggregate speed and duplex mode.

  • The turbostat tool is now included with the kernel and can be used with modern x86 processors to provide information about processor topology, and statistics such temperature and frequency.

  • For Oracle Linux 7 systems, the P-state driver (intel_pstate) is now built in to the kernel and is the default driver for Intel Sandy Bridge (and later) processors. However, for Oracle Sun x86 systems, the default driver used is still acpi_cpufreq because this driver supports the power capping features used in those systems. A new intel_pstate kernel parameter has been added. You can use the intel_pstate=force setting to force the intel_pstate driver to load on Oracle Sun x86 systems.

    For Oracle Linux 6 systems, to maintain compatibility between UEK and the Red Hat compatible kernel (RHCK), the UEK kernel does not have intel_pstate driver.

  • The SHA-512 hash algorithm is now enabled for signing kernel modules during installation.

  • The ability to use swap files that reside on NFS shares is available as a technology preview. See Section 1.4, “Technology Preview” for more detail.

  • Bug fixes for btrfs, ext4, xfs, and OCFS2 file systems.

  • Bug fixes to support Oracle Linux guests running on Microsoft Azure or Hyper-V.

  • Bug fixes for NFSv4.

1.2 Xen Improvements

  • Xen EFI support added.

  • Various fixes.

1.3 Driver Updates

The Unbreakable Enterprise Kernel supports a wide range of hardware and devices. In close cooperation with hardware and storage vendors, several device drivers have been updated by Oracle.

Table 1.1 Updated Drivers in UEK R3 QU5

Manufacturer

Driver

Version

Description

Broadcom

bnx2fc

2.8.2

NetXtreme II Fibre Channel over Ethernet (FCoE) driver

Broadcom

bnx2i

2.11.0.0

NetXtreme II iSCSI driver

Broadcom

bnx2

2.2.5m

NetXtreme II 1 Gigabit network adapter driver

Broadcom

bnx2x

1.712.10

NetXtreme II 10 Gigabit network adapter driver

Broadcom

cnic

2.5.20e

NetXtreme II Converged network interface card (NIC) driver

Cisco

enic

2.1.1.67

VIC Ethernet NIC driver

Emulex

be2iscsi

10.4.200.0o
(with upstream patches)

OneConnect Open-iSCSI driver

Emulex

lpfc

0:10.6.61.0

LightPulse Fibre Channel SCSI driver

Emulex

be2net

10.4u
(with upstream patches)

OneConnect NIC driver

HP

hpsa

3.4.4-1
(with upstream patches)

HP Smart Array controller driver

Intel

i40e

1.2.2-k

Ethernet Connection XL710 network driver

Intel

i40evf

1.0.6

XL710 X710 Virtual Function network driver

Mellanox

mlx4_en

2.1.8
(Mar 10 2015)

ConnectX HCA Ethernet driver

Microsoft

hv_netvsc

Updated

Hyper-V network driver

Microsoft

hv_storvsc

Updated

Hyper-V virtual storage driver

Microsoft

hv_utils

Updated

Hyper-V utilities

Microsoft

hv_vmbus

Updated

Hyper-V VMBus driver

1.4 Technology Preview

The following features included in the Unbreakable Enterprise Kernel Release 3 are still under development, but are made available for testing and evaluation purposes. Do not use these features on production systems.

  • DRBD (Distributed Replicated Block Device)

    A shared-nothing, synchronously replicated block device (RAID1 over network), designed to serve as a building block for high availability (HA) clusters. It requires a cluster manager (for example, pacemaker) for automatic failover.

  • Kernel module signing facility

    Applies cryptographic signature checking to modules on module load, checking the signature against a ring of public keys compiled into the kernel. GPG is used to do the cryptographic work and determines the format of the signature and key data.

  • NFS over RDMA Client

    Enables you to use NFS over the RDMA transport on the Oracle InfiniBand stack. This is more efficient than using the TCP/IPoIB transport. The technology preview does not include NFS over RDMA server support, or support for NFS over RDMA in virtualized environments. NFS version 3 and 4 are supported. Currently, only the Mellanox ConnectX-2 and ConnectX-3 Host Channel Adapters (HCAs) are supported. The client passes the full Connectathon NFS test suite using these HCAs. The Release Notes will be updated if additional adapters are supported after the initial release.

    See Section 1.4.1, “Using the NFS over RDMA Client” for details of how to use the feature.

  • Swap files on NFS shares

    Ability for a system to use swap files that reside on NFS shares. For information about using swap files, see the swapon(8) manual page and the Administrator's Guide for your Oracle Linux release.

  • Transcendent Memory

    Transcendent Memory (tmem) provides a new approach for improving the utilization of physical memory in a virtualized environment by claiming underutilized memory in a system and making it available where it is most needed. From the perspective of an operating system, tmem is fast pseudo-RAM of indeterminate and varying size that is useful primarily when real RAM is in short supply. To learn more about this technology and its use cases, see the Transcendent Memory project page at http://oss.oracle.com/projects/tmem/.

1.4.1 Using the NFS over RDMA Client

The following instructions also include details for enabling an NFS over RDMA server. These are provided as an example only, as the NFS over RDMA server is currently not supported with the UEK R3 kernel.

  1. Install an RDMA device, set up InfiniBand and enable IPoIB.

    The Oracle Linux OFED packages are available from the following channels:

    • Oracle Linux 6: ol6_x86_64_ofed_UEK

    • Oracle Linux 7: ol7_x86_64_UEKR3_OFED20

  2. Check that the RDMA device is working.

    # cat /sys/class/infiniband/driver_name/ports/1/state
    4: ACTIVE

    where driver_name is the RDMA device driver, for example mlx4_0.

  3. Verify the physical InfiniBand interfaces and links.

    Check that the hosts can be contacted through the InfiniBand switch, by using commands such as ibhosts, and ibnetdiscover.

  4. Check the connection between the NFS client and NFS server.

    You can configure the settings for an InfiniBand interface in the
    /etc/sysconfig/network-scripts/ifcfg-ibN file.

    You can use the ping command to check the connection. For example:

    nfs-server$ ip addr add 10.196.0.101/24 dev ib0
    nfs-client$ ip addr add 10.196.0.102/24 dev ib0
    nfs-server$ ping 10.196.0.102 
    nfs-client$ ping 10.196.0.101
  5. Install the nfs-utils package on the NFS client and server.

  6. Configure the NFS shares.

    Edit the /etc/exports file. Define the directories that the NFS server will make available for clients to mount, using the IPoIB addresses of the clients. For example:

    /export_dir 10.196.0.102(fsid=0,rw,async,insecure,no_root_squash) 
    /export_dir 10.196.0.0/255.255.255.0(fsid=0,rw,async,insecure,no_root_squash)
  7. On the NFS server, load the svcrdma kernel module and start the NFS service.

    Oracle Linux 6:

    # modprobe svcrdma
    # service nfs start
    # echo rdma 20049 > /proc/fs/nfsd/portlist

    Oracle Linux 7:

    # modprobe svcrdma
    # systemctl start nfs-server
    # echo rdma 20049 > /proc/fs/nfsd/portlist
    Note

    The rdma 20049 setting does not persist when the NFS service is restarted. You have to set it each time the NFS service starts.

  8. On the NFS client, load the xprtrdma kernel module and start the NFS service.

    # modprobe xprtrdma
    # service nfs start
    # mount -o proto=rdma,port=20049 host:/export /mnt 
    

    where host is the host name or IP address of the IPoIB server, and export is the name of the NFS share.

    To check that the mount over RDMA is successful, check the proto field for the mount point.

    # nfsstat -m
    /mnt from 10.196.0.102:/export
    Flags: rw,relatime,vers=4.0,rsize=262144,wsize=262144,namlen=255,hard,proto=rdma,port=20049,
    ...

    Alternatively:

    # cat /proc/mounts

Known Issues

Any mounted file systems must be unmounted on the NFS client before you shut down the NFS server. Otherwise the NFS server hangs when you shut down.

1.5 Compatibility

Oracle Linux maintains user-space compatibility with Red Hat Enterprise Linux, which is independent of the kernel version running underneath the operating system. Existing applications in user space will continue to run unmodified on the Unbreakable Enterprise Kernel Release 3 and no re-certifications are needed for RHEL certified applications.

To minimize impact on interoperability during releases, the Oracle Linux team works closely with third-party vendors whose hardware and software have dependencies on kernel modules. The kernel ABI for UEK R3 will remain unchanged in all subsequent updates to the initial release. In this release, there are changes to the kernel ABI relative to UEK R2 that require recompilation of third-party kernel modules on the system. Before installing UEK R3, verify its support status with your application vendor.

1.6 Header Packages for Development

The kernel-headers packages provide the C header files that specify the interface between user-space binaries or libraries and UEK or RHCK. These header files define the structures and constants that you need to build most standard programs or to rebuild the glibc package.

The kernel-devel and kernel-uek-devel packages provide the kernel headers and makefiles that you need to build modules against UEK and RHCK.

Chapter 2 Fixed and Known Issues

This chapter describes the fixed and known issues for the Unbreakable Enterprise Kernel Release 3.

Important

Run the yum update command regularly to ensure that the latest bug fixes and security errata are installed on your system.

2.1 Fixed Issues

The following issues have been fixed in this update.

  • Hyper-V.  With Windows Server 2008R2, if you hot-add a VHD disk using a SCSI controller, the disk is no longer detected multiple times after the virtual machine is rebooted. (Bug ID 19706977)

  • InfiniBand.  When the rds_ib_srq parameter for the rds_rdma module is enabled and the module is in use (for example when running the rds-stress tool), restarting the rdma service (which reloads the rds_rdma module) no longer generates error messages visible in dmesg or /var/log/messages. (Bug ID 18243427)

  • XFS.  On Oracle Linux 7, the bug that could cause a kernel panic if all the inodes for an XFS file system are used has been fixed. (Bug ID 19695297)

  • btrfs.  To Do (Bug ID 17087097)

  • DTrace.  To Do (Bug ID 17087097)

  • OCFS2.  To Do (Bug ID 17087097)

2.2 Known Issues

This section describes the known issues in this update.

ACPI

The following messages indicate that the BIOS does not present a suitable interface, such as _PSS or _PPC, that the acpi-cpufreq module requires:

kernel: powernow-k8: this CPU is not supported anymore, using acpi-cpufreq instead.
modprobe: FATAL: Error inserting acpi_cpufreq 

There is no known workaround for this error. (Bug ID 17034535)

btrfs

  • If you use the --alloc-start option with mkfs.btrfs to specify an offset for the start of the file system, the size of the file system should be smaller but this is not the case. It is also possible to specify an offset that is higher than the device size. (Bug ID 16946255)

  • The usage information for mkfs.btrfs reports raid5 and raid6 as possible profiles for both data and metadata. However, the kernel does not support these features and cannot mount file systems that use them. (Bug ID 16946303)

  • The btrfs filesystem balance command does not warn that the RAID level can be changed under certain circumstances, and does not provide the choice of cancelling the operation. (Bug ID 16472824)

  • Converting an existing ext2, ext3, or ext4 root file system to btrfs does not carry over the associated security contexts that are stored as part of a file's extended attributes. With SELinux enabled and set to enforcing mode, you might experience many permission denied errors after reboot, and the system might be unbootable. To avoid this problem, enforce automatic file system relabeling to run at bootup time. To trigger automatic relabeling, create an empty file named .autorelabel (for example, by using touch) in the file system's root directory before rebooting the system after the initial conversion. The presence of this file instruct SELinux to recreate the security attributes for all files on the file system. If you forget to do this and rebooting fails, either temporarily disable SELinux completely by adding selinux=0 to the kernel boot parameters, or disable enforcing of the SELinux policy by adding enforcing=0. (Bug ID 13806043)

  • Commands such as du can show inconsistent results for file sizes in a btrfs file system when the number of bytes that is under delayed allocation is changing. (Bug ID 13096268)

  • The copy-on-write nature of btrfs means that every operation on the file system initially requires disk space. It is possible that you cannot execute any operation on a disk that has no space left; even removing a file might not be possible. The workaround is to run sync before retrying the operation. If this does not help, remount the file system with the -o nodatacow option and delete some files to free up space. See https://btrfs.wiki.kernel.org/index.php/ENOSPC.

  • On Oracle Linux 6, btrfs has a limit of 237 or fewer hard links to a file from a single directory. The exact limit depends on the number of characters in the file name. The limit is 237 for a file with up to eight characters in its file name; the limit is lower for longer file names. Attempting to create more than this number of links results in the error Too many links. You can create more hard links to the same file from another directory. Although the limitation of the number of hard links in a single directory has been increased to 65535, the version of mkfs.btrfs that is provided in the btrfs-progs package does not yet support the compatibility flag for this feature. Oracle Linux 7 includes a later version of btrfs-progs package, which does support the increased number of hard links. (Bug ID 16285431)

  • If you run the btrfs quota enable command on a non-empty file system, any existing files do not count toward space usage. Removing these files can cause usage reports to display negative numbers and the file system to be inaccessible. The workaround is to enable quotas immediately after creating the file system. If you have already written data to the file system, it is too late to enable quotas. (Bug ID 16569350)

  • The btrfs quota rescan command is not currently implemented. The command does not perform a rescan and returns without displaying any message. (Bug ID 16569350)

  • When you overwrite data in a file, starting somewhere in the middle of the file, the overwritten space is counted twice in the space usage numbers that btrfs qgroup show displays. (Bug ID 16609467)

  • If you run btrfsck --init-csum-tree on a file system and then run a simple btrfsck on the same file system, the command displays a Backref mismatch error that was not previously present. (Bug ID 16972799)

  • If you use the -s option to specify a sector size to mkfs.btrfs that is different from the page size, the created file system cannot be mounted. By default, the sector size is set to be the same as the page size. (Bug ID 17087232)

  • Defragmentation can break data block sharing. Due to the copy-on-write design of btrfs, snapshots initially share the same data blocks of the original subvolume. However, when either the snapshot or the subvolume is defragmented, this sharing can be undone, resulting in a higher disk space usage.

dm-nfs Module Obsolete

In UEK R2, the dm-nfs module provided the ability to create a loopback device for a mounted NFS file or file system. For example, the feature allowed you to create the shared storage for an Oracle 3 VM cluster on an NFS file system. The dm-nfs module provided direct I/O to the server and bypassed the loop driver to avoid an additional level of page caching. The dm-nfs module is not provided with UEK R3. The loop driver can now provide the same I/O functionality as dm-nfs by extending the AIO interface to perform direct I/O. To create the loopback device, use the losetup command instead of dmsetup.

DTrace

  • Using kill -9 to terminate dtrace can leave breakpoints outstanding in processes being traced, which might sooner or later kill them.

  • Argument declarations for probe definitions cannot be declared with derived types such as enum, struct, or union.

  • The following compiler warning can be ignored for probe definition arguments of type string (which is a D type but not a C type):

    provider_def.h:line#: warning: parameter names (without types) in function declaration

ERST Message

You can safely ignore the following message that might be displayed in syslog or dmesg:

ERST: Failed to get Error Log Address Range.

The message indicates that the system BIOS does not support an Error Record Serialization Table (ERST). (Bug ID 17034576)

Ext4

  • The inline data feature that allows the data of small files to be stored inside their inodes is not yet available. The -O inline_data option to the mkfs.ext4 and tune2fs commands is not supported. (Bug ID 17210654)

  • If fallocate is used to write to an ext4 filesystem that has the bigalloc feature enabled, this causes a kernel panic. (Bug ID 20712768)

Firmware Warning Message

You can safely ignore the following firmware warning message that might be displayed on some Sun hardware:

[Firmware Warn]: GHES: Poll interval is 0 for generic hardware error source:
1, disabled.

(Bug ID 13696512)

Huge Pages

One-gigabyte (1 GB) huge pages are not currently supported for the following configurations:

  • HVM guests

  • PV guests

  • Oracle Database

Two-megabyte (2 MB) huge pages have been tested and work with these configurations.

(Bug ID 17299364, 17299871, 17271305)

Hyper-V

The following known issues affect Oracle Linux virtual machines running on Hyper-V:

  • After you take a snapshot of a virtual machine and then use the Save action to save the virtual machine state, you might not be able to revert to the virtual machine to the snapshot using the Revert action. The workaround is to click on the last snapshot listed in the Snapshot area for the virtual machine, and then select Apply. (Bug ID 20110077)

  • Oracle Linux 7 virtual machines that use Legacy Network mode lose their network connectivity if more than one virtual CPU is configured. The workaround is to configure only one virtual CPU for Oracle Linux 7 virtual machines. (Bug ID 20110058)

  • Oracle Linux 6 virtual machines running on Windows Server 2012R2 display truncated messages during a system shutdown or reboot. (Bug ID Bug 20090500)

I/O Scheduler

The Unbreakable Enterprise Kernel uses the deadline scheduler as the default I/O scheduler. For the Red Hat Compatible Kernel, the default I/O scheduler is the cfq scheduler.

ioapic Failure Messages

You can safely ignore messages such as ioapic: probe of 0000:00:05.4 failed with error -22. Such messages are the result of the ioapic driver attempting to re-register I/O APIC PCI devices that were already registered at boot time. (Bug ID 17034993)

InfiniBand

  • You might see the following warning messages if you use the ibportstate disable command to disable a switch port:

    ibwarn: [2696] _do_madrpc: recv failed: Connection timed out
    ibwarn: [2696] mad_rpc: _do_madrpc failed; dport (Lid 38)
    ibportstate: iberror: failed: smp set portinfo failed

    You can safely ignore these warnings. (Bug ID 16248314)

  • The Internet Protocol over InfiniBand (IPoIB) driver supports the use of either connected mode or datagram mode with an interface, where datagram mode is the default mode. Changing the mode of an InfiniBand interface by echoing either connected or datagram to /sys/class/net/ibN/mode is not supported. It is also not possible to change the mode of an InfiniBand interface while it is enabled.

    To change the IPoIB mode of an InfiniBand interface:

    1. Edit the /etc/sysconfig/network-scripts/ifcfg-ibN configuration file, where N is the number of the interface:

      • To configure connected mode, specify CONNECTED_MODE=yes in the file.

      • To configure datagram mode, either specify CONNECTED_MODE=no in the file or do not specify this setting at all (datagram mode is enabled by default).

      Note

      Before saving your changes, make sure that you have not specified more than one setting for CONNECTED_MODE in the file.

    2. To enable the specified mode on the interface, use the following commands to take down the interface and bring it back up:

      # ifdown ibN
      # ifup ibN

    (Bug ID 17479833)

Linux Containers (LXC)

  • The root user in a container can affect the configuration of the host system by setting some /proc entries. (Bug ID 17190287)

  • Using yum to update packages inside the container that use init scripts can undo changes made by the Oracle template.

  • Migrating live containers (lxc-checkpoint) is not yet supported.

  • Oracle Database is not yet supported for use with Linux Containers. The following information is intended for those who want to experiment with such a configuration.

    The following /proc parameter files may only be set on the host and not for individual containers:

    • /proc/sys/fs/aio-max-nr

    • /proc/sys/net/core/rmem_default

    • /proc/sys/net/core/rmem_max

    • /proc/sys/net/core/wmem_default

    • /proc/sys/net/core/wmem_max

    • /proc/sys/net/ipv4/ip_local_port_range

    Setting the parameters in the host to the Oracle recommended values sets them for all containers and allows the Oracle database to run in a container. For more information, see Configuring Kernel Parameters and Resource Limits. (Bug ID 17217854)

  • If a Device or resource busy - failed to set memory.use_hierarchy to 1 error message is displayed when you start a container, edit the /etc/cgconfig.conf file and add the following:

    group . {
    memory {
    memory.use_hierarchy = "1";
    }
    }

    (Bug ID 19237222)

Missing Documentation for PCIe Kernel Parameters

The following documentation for some PCIe kernel parameters is not included in the kernel-parameters.txt file in the kernel-uek-doc package:

pcie_bus_tune_off

Disable PCIe MPS (Max Payload Size) tuning and use the BIOS-configured MPS defaults.

pcie_bus_safe

Set every device's MPS to the largest value supported by all devices below the root complex.

pcie_bus_perf

Set device MPS to the largest allowable MPS based on its parent bus. Also set MRRS (Max Read Request Size) to the largest supported value (no larger than the MPS that the device or bus can support) for best performance.

pcie_bus_peer2peer

Set every device's MPS to 128B, which every device is guaranteed to support. This configuration allows peer-to-peer DMA between any pair of devices, possibly at the cost of reduced performance. This also guarantees that hot-added devices will work.

Mellanox Driver (mlx4_en)

The Mellanox mlx4_en driver fails to auto-sense the data link and, as a result, the driver is not automatically loaded. (Bug ID 20103438)

RDMA Does Not Load the mlx4_ib Module

If you enable the OFED stack and the RDMA service but the version of the RDMA package is lower than rdma‑3.10‑3.0.2.el6, the RDMA service does not load the mlx4_ib module automatically.

To configure the RDMA service to load the mlx4_ib module at boot time:

  1. Edit /etc/rdma/rdma.conf and set the entry MLX4_LOAD=yes in this file.

  2. To make the change take effect, restart the RDMA service or reboot the system.

sched_yield() Settings for CFS

For the Unbreakable Enterprise Kernel, kernel.sched_compat_yield=1 is set by default. For the Red Hat Compatible Kernel, kernel.sched_compat_yield=0 is used by default.

Slow Performance With Multipath Devices

Starting with UEK R2, the device mapper has had the capability to check whether the underlying storage device has advertised the need to flush the data that resides in the device's cache to its non-volatile storage. For a data integrity operation, such as fsync and sync, the operation will now need to include the time to flush the device's cache (if it is advertised). Such an operation will appear to be slower when compared to a previous older kernel, however this is the correct behavior. (Bug ID 17823743)

Soft Lockup Errors When Booting

When upgrading or installing the UEK R3 kernel on fast hardware, usually with SAN storage attached, the kernel can fail to boot and BUG: soft lockup messages are displayed in the console log. The workaround is to increase the baud rate from the default value of 9600 by amending the kernel boot line in /boot/grub/grub.conf to include an appropriate console setting, for example:

console=ttyS0,115200n8

A value of 115200 is recommended as smaller values such as 19200 are known to be insufficient for some systems (for example, see http://docs.oracle.com/cd/E19045-01/blade.x6220/820-0048-18/sp.html#0_pgfId-1002490). If the host implements an integrated system management infrastructure, such as ILOM on Sun and Oracle systems or iLO on HP systems, configure the integrated console baud rate to match the setting for the host system. Otherwise, the integrated console is likely to display garbage characters. (Bug ID 17064059, 17252160)

Transparent Huge Pages

The Transparent Huge Pages (THP) feature is disabled. Following extensive benchmarking and testing, Oracle found that THP caused a performance degradation of between 5 and 10% for some workloads. This performance degradation was a result of a slower memory allocator code path being used even when the applications were not using THP. When the fact that huge pages are not swappable was taken into account, the positive effect that THP should provide was outweighed by its negative effects.

After installing this UEK release, you cannot enable THP (for example, by specifying kernel boot parameters). The THP settings under /sys/kernel/mm/transparent_hugepage have also been removed. A future update might contain an updated THP implementation which resolves the performance issue.

Note

This change does not affect support for applications that use explicit huge pages (for example, Oracle Database).

(Bug ID 16823432)

User Namespaces

The kernel functionality (CONFIG_USER_NS) that allows unprivileged processes to create namespaces for users inside which they have root privileges is not currently implemented because of a clash with the implementation of XFS. This functionality is primarily intended for use with Linux Containers. As a result, the lxc-checkconfig command displays User namespace: missing. (Bug ID 16656850)

Virtualization

  • When booting UEK R3 as a PVHVM guest, you can safely ignore the following kernel message:

    register_vcpu_info failed:
              err=-38

    (Bug ID 13713774)

  • Under Oracle VM Server 3.1.1, migrating a PVHVM guest that is running the UEK R3 kernel causes a disparity between the date and time as displayed by date and hwclock. To prevent this from occurring, upgrade to Oracle VM Server 3.2.1 or later. The workaround post migration is either to run the command hwclock --hctosys on the guest or to reboot the guest. (Bug ID 16861041)

  • On virtualized systems that are built on Xen version 3, including all releases of Oracle VM 2 including 2.2.2 and 2.2.3, disk synchronization requests for ext3 and ext4 file systems result in journal corruption with kernel messages similar to the following being logged:

    blkfront: barrier: empty write xvda op failed
    blkfront: xvda: barrier or flush: disabled

    In addition, journal failures such as the following might be reported:

    Aborting journal on device xvda1

    The workaround is to add the mount option barrier=0 to all ext3 and ext4 file systems in the guest VM before upgrading to UEK R3. For example, you would change a mount entry such as:

    UUID=4e4287b1-87dc-47a8-b69a-075c7579eaf1  /  ext3  defaults  1 1

    so that it reads:

    UUID=4e4287b1-87dc-47a8-b69a-075c7579eaf1  /  ext3  defaults,barrier=0  1 1

    This issue does not apply to Xen 4 based systems, such as Oracle VM 3. (Bug ID 17310816)

  • Xen does not support the crashkernel=auto parameter for Kdump configuration. (Bug ID 18174580)

  • Mounting or changing an ISO image in a PVHVM guest results in exception messages in the Oracle VM console. The ISO image itself is mounted correctly and is accessible. (Bug ID 19972081)

  • You cannot increase (hot plug) the number of virtual CPUs in a running Oracle Linux 7 guest using the xm vcpu-set command. Decreasing the number of virtual CPUs does work. (Bug ID 18865156)

  • In order to use jumbo frames with any network interface card on an Oracle VM Server, you must increase the swiotlb kernel parameter to 256 by setting swiotlb=256 in the kernel boot line in /boot/grub/grub.conf. (Bug ID 20333068)

X.509 Certificates for Module Verification

The system reports a message similar to the following if there is a problem loading an in-kernel X.509 module verification certificate at boot time:

Loading module verification certificates 
X.509: Cert 0c21da3d73dcdbaffc799e3d26f3c846a3afdc43 is not yet valid 
MODSIGN: Problem loading in-kernel X.509 certificate (-129)

This error occurs because the hardware clock lags behind the system time as shown by hwclock, for example:

# hwclock
Tue 20 Aug 2013 01:41:40 PM EDT -0.767004 seconds

The solution is to set the hardware clock from the system time by running the following command:

# hwclock --systohc

After correcting the hardware clock, no error should be seen at boot time, for example:

Loading module verification certificates 
MODSIGN: Loaded cert 'Slarti: Josteldalsbreen signing key: 
0c21da3d73dcdbaffc799e3d26f3c846a3afdc43'

(Bug ID 17346862)

XFS

  • In some circumstances, xfsdump can fail when the file system to be backed up is specified as a mount point, for example:

    xfsdump: ERROR: /mnt/myxfs/ does not identify a file system

    The workaround is to specify the file system by its device name, for example /dev/sdb. (Bug ID 18483275)

  • In a virtual machine, the intensive direct I/O on files which are being fragmented by fallocate and punch_hole in parallel may result, in some circumstances, in data corruption with the error Invalid or incomplete multibyte or wide character. (Bug ID 18711409)

  • The following message might be displayed when you use the xfs_growfs command:

     xfs_growfs: cannot find mount point for path `mount_point': Success 

    The message is caused by an incorrect mounted project path listed in the XFS project quota initialization file, /etc/projects. If you are not using project quotas, remove the /etc/projects file. (Bug ID 18886520)

  • On Oracle Linux 6, an XFS file system can become corrupted if all of its inodes are used. (Bug ID 19217280)

  • On Oracle Linux 7, xfs_copy fails to copy a file system if the device sector size more than 512 bytes. (Bug ID 19267663)

  • xsf_repair causes a segmentation fault when you try repair a file system using a short reporting interval (-t). (Bug ID 20015850)

  • When you create an XFS file system using the -i maxpct option, it does not actually limit the space allocated to inodes. (Bug ID 20430515)

  • Mounting an XFS file system that was created using the -n ftype=1 option results in a mount error and the file system cannot be mounted. The ftype option is not supported in UEK R3. (Bug ID 20511541)

Chapter 3 Installation and Availability

Unbreakable Enterprise Kernel Release 3 (UEK R3) is supported only on the x86-64 architecture.

Oracle Linux 7

UEK R3 is the default boot kernel for fresh installations of Oracle Linux 7.

Oracle Linux 6

You can install UEK R3 on Oracle Linux 6 Update 4 or later, running either the Red Hat compatible kernel or a previous version of the Unbreakable Enterprise Kernel. If you are still running an older version of Oracle Linux, first update your system to the latest available update release.

Starting with Oracle Linux 6 Update 5 for x86-64, UEK R3 is the default boot kernel for fresh installations of Oracle Linux 6.

For systems that are currently running a previous version of the Unbreakable Enterprise Kernel (UEK R2) or the Red Hat compatible kernel (RHCK), you can switch to UEK R3 at any time. For details, see:

Kernel Source Code

The kernel's source code is available from a public git source code repository at:
https://oss.oracle.com/git/?p=linux-uek3-3.8.git.

3.1 Upgrading to the Latest UEK Release

For systems that are currently running UEK R3, you upgrade to the latest UEK release as follows:

  1. Ensure the system is configured to receive updates from the correct channels or repositories.

    For Oracle Linux 7, subscribe to either the ol7_x86_64_UEKR3 channel on ULN, or the ol7_UEKR3 repository on the Oracle public yum server.

    For Oracle Linux 6, subscribe to either the ol6_x86_64_UEKR3_latest channel on ULN, or the ol6_UEKR3_latest repository on the Oracle public yum server.

  2. Upgrade all packages on the system, including kernel packages.

    # yum update

    By default, the boot manager automatically enables the most recent kernel version so you do not need to change your GRUB or GRUB 2 configuration.

  3. Reboot the system.

    Oracle Linux 7:

    # systemctl reboot

    Oracle Linux 6:

    # shutdown -r now

3.2 Switching an Oracle Linux 6 System to UEK R3 (ULN)

If you have a subscription to Oracle Unbreakable Linux support, you can obtain the packages for Unbreakable Enterprise Kernel Release 3 (UEK R3) by registering your system with the Unbreakable Linux Network (ULN) and subscribing it to additional channels.

Before you begin:

The following instructions also include steps for updating a system to use the Oracle OpenFabrics Enterprise Distribution (OFED) tools for UEK R3.

To Switch a System to UEK R3:

  1. Using a browser, log in at http://linux.oracle.com with the ULN user name and password that you used to register the system.

  2. On the Systems tab, click the link name of your system in the list of registered machines.

  3. On the System Details page, click Manage Subscriptions.

  4. On the System Summary page, select each required channel in the Available Channels list and click the right arrow to move the channel to the Subscribed Channels list.

    The kernel image and user-space packages are available on the following ULN channels:

    Channel Name and Label

    Description

    Oracle Linux 6 Latest (x86_64)

    ol6_x86_64_latest

    All packages released for Oracle Linux 6 (x86_64) including the latest errata packages. (x86_64).

    Unbreakable Enterprise Kernel Release 3 for Oracle Linux 6 (x86_64) - Latest

    ol6_x86_64_UEKR3_latest

    Latest packages for Unbreakable Enterprise Kernel Release 3 for Oracle Linux 6 (x86_64).

    Contains the kernel-uek*,
    dtrace-modules-*, libdtrace-*, and uname26 packages.

    Oracle Linux 6 Dtrace Userspace Tools (x86_64) - Latest

    ol6_x86_64_Dtrace_userspace_latest

    The latest DTrace user space tools for Oracle Linux 6 (x86_64).

    Contains the dtrace-utils* packages.

    OFED supporting tool packages for Unbreakable Enterprise Kernel on Oracle Linux 6 (x86_64)

    ol6_x86_64_ofed_UEK

    Latest OpenFabrics Enterprise Distribution (OFED) supporting tools for the Unbreakable Enterprise Kernel (UEK) on Oracle Linux 6 (x86_64).

    HA Utilities for MySQL and Oracle Linux 6 (x86_64)

    ol6_x86_64_mysql-ha-utils

    Management Utilities for MySQL HA with Oracle Linux 6.

    Contains the drbd84-utils package.

    As a minimum, you should subscribe the system to the ol6_x86_64_latest and the ol6_x86_64_UEKR3_latest channels. These channels are enabled by default when you register an Oracle Linux 6 system with ULN.

    Caution

    Take care not to select the ol6_x86_64_UEK_BETA channel.

    Because you are switching to the latest UEK kernel, you no longer need to subscribe the system to the previous UEK R2 (ol6_x86_64_UEK_latest) channel.

  5. When you have finished selecting channels, click Save Subscriptions and log out of ULN.

  6. Log in as root on the system.

  7. (Optional) Install the Oracle OFED packages for UEK R3.

    Perform the following steps only if want to install or update the Oracle OFED packages, or you want to replace the OFED packages installed from either the Oracle Linux 6 full installation DVD image, or from the _base or the _latest channels on ULN.

    The Oracle OFED packages are available only for x86_64 platforms.

    1. Ensure the system is subscribed to the ol6_x86_64_ofed_UEK channel on ULN.

    2. Edit /etc/yum/pluginconf.d/rhnplugin.conf and add the following lines to the end of the file:

      [ol6_x86_64_ofed_UEK]
      priority=20 
    3. Install the yum-plugin-priorities package from the ol6_x86_64_UEKR3_latest channel:

      # yum install yum-plugin-priorities
    4. Downgrade any OFED packages that are already present on the system if the package version number in the ol6_x86_64_ofed_UEK channel is lower than the installed one.

      You can use the yum --showduplicates list command to check the package version numbers, for example:

      # yum yum --showduplicates list rdma
      ...
      Installed Packages 
      rdma.noarch 6.6_3.15-1.0.1.el6 @ol6_u6_x86_64_base 
      Available Packages 
      rdma.noarch 3.6-1.0.5.el6 ol6_x86_64_ofed_UEK
      

      You downgrade a package with the yum downgrade command, for example:

      # yum downgrade rdma
      ...
      Removed:
        rdma.noarch 6.6_3.15-1.0.1.el6
      
      Installed:
        rdma.noarch 3.6-1.0.5.el6
      
      Complete! 
      
    5. Remove the ibutils-libs package (if present):

      # yum remove ibutils-libs
    6. Install the Oracle OFED packages from the ol6_x86_64_ofed_UEK channel as required, for example:

      # yum install ibutils 
  8. Upgrade all packages on the system, including kernel packages.

    # yum update

    By default, the boot manager automatically enables the most recent kernel version so you do not need to change your GRUB configuration.

  9. Reboot the system.

    # shutdown -r now

3.3 Switching an Oracle Linux 6 System to UEK R3 (Public Yum)

If your system is not registered with ULN, you can obtain most of the packages for Unbreakable Enterprise Kernel Release 3 (UEK R3) from Oracle Public Yum by subscribing it to additional repositories.

Before you begin, check that the system meets the requirements for installing UEK R3, see Chapter 3, Installation and Availability.

The following instructions also include steps for updating a system to use the Oracle OpenFabrics Enterprise Distribution (OFED) tools for UEK R3.

To Switch a System to UEK R3:

  1. Log in as root on the system.

  2. Change directory to /etc/yum.repos.d.

    # cd /etc/yum.repos.d
    Note

    This assumes that yum on your system is configured to find repository files in the default /etc/yum.repos.d directory.

  3. Move the existing yum repository file to a backup file, for example:

    # mv /etc/yum.repos.d/public-yum-ol6.repo /etc/yum.repos.d/public-yum-ol6.repo.bck

  4. Download the latest Oracle Linux 6 repository configuration file, http://public-yum.oracle.com/public-yum-ol6.repo, for example:

    # wget -O /etc/yum.repos.d/public-yum-ol6.repo http://public-yum.oracle.com/public-yum-ol6.repo

  5. Enable the required repositories by editing the public-yum-ol6.repo file.

    You enable or disable repositories in the file by setting the value of the enabled directive to 1 or 0 as required.

    The kernel image and user-space packages are available on the following Oracle Public Yum repositories:

    Repository

    Description

    ol6_latest

    All packages released for Oracle Linux 6 (x86_64) including the latest errata packages.

    ol6_UEKR3_latest

    Latest packages for Unbreakable Enterprise Kernel Release 3 for Oracle Linux 6.

    Contains the kernel-uek*, dtrace-modules-*, libdtrace-*, and uname26 packages.

    ol6_ofed_UEK

    Latest OFED supporting tools for the Unbreakable Enterprise Kernel (UEK) on Oracle Linux 6 (x86_64).

    As a minimum, you should enable the ol6_latest and the ol6_UEKR3_latest repositories.

    Note

    The DTrace and DRBD utility packages are not available on Public Yum.

    Because you are switching to the latest UEK kernel, you can disable the previous UEK R2 (ol6_UEK_latest) repository.

    In the following example, the ol6_UEKR3_latest repository is enabled, and the ol6_UEK_latest repository is disabled:

    [ol6_UEKR3_latest]
    name=Latest Unbreakable Enterprise Kernel for Oracle Linux $releasever ($basearch)
    baseurl=http://public-yum.oracle.com/repo/OracleLinux/OL6/UEKR3/latest/$basearch/
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle
    gpgcheck=1
    enabled=1
    
    [ol6_UEK_latest]
    name=Latest Unbreakable Enterprise Kernel for Oracle Linux $releasever ($basearch)
    baseurl=http://public-yum.oracle.com/repo/OracleLinux/OL6/UEK/latest/$basearch/
    gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle
    gpgcheck=1
    enabled=0
    
  6. (Optional) Install the Oracle OFED packages for UEK R3.

    Perform the following steps only if want to install or update the Oracle OFED packages, or you want to replace the OFED packages installed from either the Oracle Linux 6 full installation DVD image, or from the _base or the _latest repositories on public yum.

    The Oracle OFED packages are available only for x86_64 platforms.

    1. Ensure the ol6_ofed_UEK repository is enabled on the system.

    2. Install the yum-plugin-priorities package from the ol6_latest repository:

      # yum install yum-plugin-priorities
    3. Downgrade any OFED packages that are already present on the system if the package version number in the ol6_ofed_UEK repository is lower than the installed one.

      You can use the yum --showduplicates list command to check the package version numbers, for example:

      # yum yum --showduplicates list rdma
      ...
      Installed Packages 
      rdma.noarch 6.6_3.15-1.0.1.el6 @ol6_u6_base 
      Available Packages 
      rdma.noarch 3.6-1.0.5.el6 ol6_ofed_UEK
      

      You downgrade a package with the yum downgrade command, for example:

      # yum downgrade rdma
      ...
      Removed:
        rdma.noarch 6.6_3.15-1.0.1.el6
      
      Installed:
        rdma.noarch 3.6-1.0.5.el6
      
      Complete! 
      
    4. Remove the ibutils-libs package (if present):

      # yum remove ibutils-libs
    5. Install the Oracle OFED packages from the ol6_ofed_UEK repository as required, for example:

      # yum install ibutils 
  7. Upgrade all packages on the system, including kernel packages.

    # yum update

    By default, the boot manager automatically enables the most recent kernel version so you do not need to change your GRUB configuration.

  8. Reboot the system.

    # shutdown -r now

Appendix A Legal Notices

This appendix contains the legal notices that apply to this document.

A.1 Oracle Legal Notices

Copyright © 2015, Oracle and/or its affiliates. All rights reserved.

This software and related documentation are provided under a license agreement containing restrictions on use and disclosure and are protected by intellectual property laws. Except as expressly permitted in your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast, modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by any means. Reverse engineering, disassembly, or decompilation of this software, unless required by law for interoperability, is prohibited.

The information contained herein is subject to change without notice and is not warranted to be error-free. If you find any errors, please report them to us in writing.

If this is software or related documentation that is delivered to the U.S. Government or anyone licensing it on behalf of the U.S. Government, then the following notice is applicable:

U.S. GOVERNMENT END USERS: Oracle programs, including any operating system, integrated software, any programs installed on the hardware, and/or documentation, delivered to U.S. Government end users are "commercial computer software" pursuant to the applicable Federal Acquisition Regulation and agency-specific supplemental regulations. As such, use, duplication, disclosure, modification, and adaptation of the programs, including any operating system, integrated software, any programs installed on the hardware, and/or documentation, shall be subject to license terms and license restrictions applicable to the programs. No other rights are granted to the U.S. Government.

This software or hardware is developed for general use in a variety of information management applications. It is not developed or intended for use in any inherently dangerous applications, including applications that may create a risk of personal injury. If you use this software or hardware in dangerous applications, then you shall be responsible to take all appropriate fail-safe, backup, redundancy, and other measures to ensure its safe use. Oracle Corporation and its affiliates disclaim any liability for any damages caused by use of this software or hardware in dangerous applications.

Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners.

Intel and Intel Xeon are trademarks or registered trademarks of Intel Corporation. All SPARC trademarks are used under license and are trademarks or registered trademarks of SPARC International, Inc. AMD, Opteron, the AMD logo, and the AMD Opteron logo are trademarks or registered trademarks of Advanced Micro Devices. UNIX is a registered trademark of The Open Group.

This software or hardware and documentation may provide access to or information about content, products, and services from third parties. Oracle Corporation and its affiliates are not responsible for and expressly disclaim all warranties of any kind with respect to third-party content, products, and services unless otherwise set forth in an applicable agreement between you and Oracle. Oracle Corporation and its affiliates will not be responsible for any loss, costs, or damages incurred due to your access to or use of third-party content, products, or services, except as set forth in an applicable agreement between you and Oracle.

Documentation Accessibility

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Access to Oracle Support

Oracle customers that have purchased support have access to electronic support through My Oracle Support. For information, visit http://www.oracle.com/pls/topic/lookup?ctx=acc&id=info or visit http://www.oracle.com/pls/topic/lookup?ctx=acc&id=trs if you are hearing impaired.

A.2 DocBook XSL License

Copyright © 1999-2007 Norman Walsh

Copyright © 2003 Jiri Kosek

Copyright © 2004-2007 Steve Ball

Copyright © 2005-2008 The DocBook Project

Copyright © 2011-2012 O'Reilly Media

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ``Software''), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

Except as contained in this notice, the names of individuals credited with contribution to this software shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the individuals in question.

Any stylesheet derived from this Software that is publicly distributed will be identified with a different name and the version strings in any derived Software will be changed so that no possibility of confusion between the derived package and this Software will exist.

Warranty

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL NORMAN WALSH OR ANY OTHER CONTRIBUTOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Web-based Help from DocBook XML

Copyright © 2008-2012 Kasun Gajasinghe, David Cramer

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

  • The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

  • Except as contained in this notice, the names of individuals credited with contribution to this software shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the individuals in question.

  • Any stylesheet derived from this Software that is publicly distributed will be identified with a different name and the version strings in any derived Software will be changed so that no possibility of confusion between the derived package and this Software will exist.

Warranty: THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL DAVID CRAMER, KASUN GAJASINGHE, OR ANY OTHER CONTRIBUTOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Certain search characteristics associated with the DocBook XSL webhelp stylesheets are provided as javascript files generated using Apache Lucene and other fourth party technologies.

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                        http://www.apache.org/licenses/

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