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E58283-01
December 2014
Abstract
This document contains information on Quarterly Update 4 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: 2014-12-04 (revision: 2451)
Table of Contents
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.
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.
For information about Oracle's commitment to accessibility, visit the Oracle Accessibility Program website at http://www.oracle.com/pls/topic/lookup?ctx=acc&id=docacc.
Oracle customers 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.
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.
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Table of Contents
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 3.8.13-55 release is the fourth 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.
Automatic loading of DTrace modules. You can now specify
entries in /etc/dtrace-modules
that
define the modules that DTrace should load automatically
when it starts. For example:
# The modules to be loaded follow this comment, one per line profile systrace sdt fasttrap
For more information about the modules and providers that are included with the Oracle Linux implementation of DTrace, see the Oracle Linux DTrace Tutorial.
PMC-Sierra PM8001 SAS/SATA controller driver
(pm8001
) has been added. This driver
supports the new Adaptec Series 7H family of 8-port and
16-port PCIe gen3 SAS/SATA host bus adapters.
Intel XL710 X710 Virtual Function network driver
(i40evf
) has been added.
The P-state driver (intel_pstate
) for the
Intel Sandy Bridge processor has been added.
Various network performance improvement patches to support Oracle Linux virtual machines running on Microsoft Hyper-V.
New kernel event actions (uevents) are generated when certain SCSI ASC/ASCQ unit attention codes are received, see the kernel change log for details. You can configure your own udev rules to handle these events, as there is no default processing.
NFS over Remote Data Memory Access (RDMA) Client is available as a technology preview. See Section 1.4, “Technology Preview” for more detail.
Support for Xen UEFI hypercall.
Backport of fixes and features from Xen Linux 3.17.
Backport of syncing CMOS real-time clock (RTC) as well as Xen wallclock.
Xen pciback fixes for PCI passthrough.
Backport xen_nopv
parameter to disable PV
extensions for HVM guests.
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.
Broadcom
NetXtreme II Fibre Channel over Ethernet driver
(bnx2fc
) updated to 2.5.5.1.
NetXtreme II iSCSI driver (bnx2i
)
updated to 2.7.10.31d1.
Emulex
OneConnect (previously known as Blade Engine 2) Open-iSCSI
driver (be2iscsi
) updated to
10.4.114.0o.
LightPulse Fibre Channel SCSI (previously known as Fibre
Channel HBA) driver (lpfc
) updated to
0:10.2.8061.0.
HP
Upstream patches have been applied to the HP Smart Array
CCISS driver (cciss
). The driver
version number is unchanged.
Upstream patches have been applied to the HP Smart Array
Controller driver (hpsa
) The driver
version number is unchanged.
Intel
Upstream patches have been applied to the NVM Express
device driver (nvme
). The driver
version number is unchanged.
LSI
Upstream patches have been applied to the Fusion MPT SAS
host driver (mptsas
). The driver
version number is unchanged.
Upstream patches have been applied to the LSI MegaRAID SAS
driver (megaraid_sas
). The driver
version number is unchanged.
PMC
PMC-Sierra PM8001 SAS/SATA controller driver
(pm8001
) version 0.1.36 added.
QLogic
Fibre Channel HBA driver (qla2xxx
)
updated to 8.07.00.16.39.0-k.
Broadcom
NetXtreme II 1 Gigabit network adapter driver
(bnx2
) updated to 2.2.5i.
NetXtreme II 10 Gigabit network adapter driver
(bnx2x
) updated to 1.710.51.
NetXtreme II Converged Network Interface Card core driver
(cnic
) updated to 2.5.20b.
Upstream patches have been applied to the Tigon3 Ethernet
adapter driver (tg3
). The driver
version number is unchanged.
Emulex
OneConnect (previously known as Blade Engine 2) NIC driver
(be2net
) updated to 10.4u.
Intel
Gigabit Virtual Function driver (igbvf
)
updated to 2.3.5.
10 Gigabit PCI Express network driver
(ixgbe
) updated to 3.22.3.
10 Gigabit PCI Express virtual function driver
(ixgbevf
) updated to 2.15.3.
Ethernet Connection XL710 Network Driver
(i40e
) updated to 0.3.43-k.
XL710 X710 Virtual Function network driver
(i40evf
) version 0.9.21 added.
QLogic
1/10 GbE Converged/Intelligent Ethernet adapter driver
(qlcnic
) updated to 5.3.62.
Upstream patches have been applied to the 10 Gigabit PCI-E
Ethernet adapter driver (qlge
). The
driver version number is unchanged.
Upstream patches have been applied to the NetXen (1/10)
Gigabit Intelligent Ethernet driver
(netxen_nic
). The driver version number
is unchanged.
Intel
The P-state driver (intel_pstate
) for
the Intel Sandy Bridge processor has been added to UEK R3.
In cpufreq terminology, this driver implements a scaling
driver with an internal governor.
To enable the intel_pstate
driver on
Sandy Bridge or later processors, you can blacklist
preferred cpufreq drivers such as
acpi-cpufreq
by running the following
command:
# echo 'blacklist acpi-cpufreq' > /etc/modprobe.d/cpufreq.conf
Unlike the acpi-cpufreq
driver, the
intel_pstate
driver does not support
the CPU power capping feature on Oracle Sun x86 Servers.
The following features included in the Unbreakable Enterprise Kernel Release 3 are still under development, but are made available for testing and evaluation purposes.
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.
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/.
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.
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.
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
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
.
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.
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-ib
file.
N
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
Install the nfs-utils
package on the
NFS client and server.
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)
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
The rdma 20049
setting does not
persist when the NFS service is restarted. You have to
set it each time the NFS service starts.
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
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.
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.
Table of Contents
This chapter describes the fixed and known issues for the Unbreakable Enterprise Kernel Release 3.
Run the yum update command regularly to ensure that the latest bug fixes and security errata are installed on your system.
The following issues have been fixed in this update.
bnx2i Driver
Fixed the issue with the bnx2i driver that caused a kernel panic when the iscsiadm command is used. (Bug 19726959)
DTrace
Dtrace modules can now be loaded automatically. (Bug ID 19821254)
If initial process grabs or creations fail, they no longer cause intermittent core dumps. (Bug ID 19679998)
It was possible for an executed process to terminate abnormally if DTrace user-space tracing was already active.
DTrace could lose track of the state of a process, or even
become deadlocked, if the process called
exec()
while DTrace was inserting a
breakpoint.
ext3
The problem that caused file system corruption in a virtual machine when the virtual disks are configured as sparse files in an ext3 repository has been fixed. (Bug ID 19220057)
Hyper-V
Reloading Hyper-V kernel modules using modprobe no longer results in a kernel panic.
The Kdump kernel crash feature now works as expected in Oracle Linux virtual machines on Windows Server 2012 R2 hosts. (Bug 19727047)
The hot-adding memory feature now works with Oracle Linux virtual machines. (Bug 19441989)
Microcode
Systems with Haswell CPUs no longer experience lengthy boot delays due to microcode loading issues.
nvme Driver
Fixed the bug with the nvme
driver that
caused hot-unplugged and re-plugged devices to show up with
zero capacity and an erroneous detected capacity
change
message in
/var/log/messages
. (Bug 19566288)
OCFS2
OCFS2 no longer hangs due to a wrong locking order. (Bug ID 19547845, 19249791)
Enabling the global heartbeat no longer causes a node to
reboot when the cluster configuration
(cluster.conf
) is inconsistent across
the stack. (Bug 19549715)
qla2xxx Driver
Fixed incorrectly returned PCI EEH busy
warning message. (Bug ID 19916135)
Virtualization
Increasing the number of virtual CPUs on a running PVM guest (xm vcpu-set) no longer causes a soft lockup. (Bug 19261720)
Shutting down or rebooting a PVM guest no longer causes a kernel panic. (Bug 19803968)
XFS
Turning project quotas off with xfs_quota
no longer fails with an XFS_QUOTARM: Invalid
argument
error. (Bug ID 19815141)
This section describes the known issues in this update.
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)
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.
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.
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
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)
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)
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)
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)
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)
With Windows Server 2008R2, if you hot-add a VHD disk using a SCSI controller, the disk is detected multiple times after the virtual machine is rebooted. (Bug ID 19706977)
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.
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)
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/ib
is not supported. It is also not possible to change the
mode of an InfiniBand interface while it is enabled.
N
/mode
To change the IPoIB mode of an InfiniBand interface:
Edit the
/etc/sysconfig/network-scripts/ifcfg-ib
configuration file, where
N
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).
Before saving your changes, make sure that you
have not specified more than one setting for
CONNECTED_MODE
in the file.
To enable the specified mode on the interface, use the following commands to take down the interface and bring it back up:
#ifdown ib
#N
ifup ib
N
(Bug ID 17479833)
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) generates error
messages visible in dmesg or
/var/log/messages
. (Bug ID 18243427)
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)
The following documentation for some PCIe kernel parameters is
not included in the kernel-parameters.txt
file in the kernel-uek-doc
package:
Disable PCIe MPS (Max Payload Size) tuning and use the BIOS-configured MPS defaults.
Set every device's MPS to the largest value supported by all devices below the root complex.
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.
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.
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)
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:
Edit /etc/rdma/rdma.conf
and set the
entry MLX4_LOAD=yes
in this file.
To make the change take effect, restart the RDMA service or reboot the system.
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.
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)
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)
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.
This change does not affect support for applications that use explicit huge pages (for example, Oracle Database).
(Bug ID 16823432)
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)
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)
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)
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, a kernel panic can occur if all the inodes for an XFS file system are used. (Bug ID 19695297)
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).
Table of Contents
Unbreakable Enterprise Kernel Release 3 (UEK R3) is only supported on the x86-64 architecture.
UEK R3 is the default boot kernel for fresh installations of Oracle Linux 7.
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:
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.
For systems that are currently running UEK R3, you upgrade to the latest UEK release as follows:
Ensure the system is configured to receive updates from the correct channels or repositories.
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.
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.
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.
Reboot the system.
Oracle Linux 6:
# shutdown -r now
Oracle Linux 7:
# systemctl reboot
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:
Ensure the system is registered with ULN.
For information about registering with ULN, see the Oracle Linux Unbreakable Linux Network User's Guide.
Check that the system meets the requirements for installing UEK R3.
For details, see Chapter 3, Installation and Availability.
Remove some of the existing OpenFabrics Enterprise Distribution (OFED) packages.
You only need to do this if you have installed any OFED packages on your system and you want to replace them with the latest OFED tools packages. The packages have to be removed manually, see Section 3.4, “Upgrading OFED Packages on Oracle Linux 6 Systems”.
To Switch a System to UEK R3:
Using a browser, log in at http://linux.oracle.com with the ULN user name and password that you used to register the system.
On the Systems tab, click the link named of your system in the list of registered machines.
On the System Details page, click Manage Subscriptions.
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)
| 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
| Latest packages for Unbreakable Enterprise Kernel Release 3 for Oracle Linux 6 (x86_64).
Contains the |
Oracle Linux 6 Dtrace Userspace Tools (x86_64) - Latest
| The latest DTrace userspace tools for Oracle Linux 6 (x86_64).
Contains the |
OFED supporting tool packages for Unbreakable Enterprise Kernel on Oracle Linux 6 (x86_64)
| 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)
| Management Utilities for MySQL HA with Oracle Linux 6.
Contains the |
As a minimum, you should subscribe the system to the
ol6_x86_64_latest
and the
ol6_x86_64_UEKR3_latest
channels. If
required, you can also add the channels for the DTrace,
OFED, and DRBD packages.
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.
When you have finished selecting channels, click Save Subscriptions and log out of ULN.
Log in as root
on the system.
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.
Reboot the system.
# shutdown -r now
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.
For details, see Chapter 3, Installation and Availability.
Remove some of the existing OpenFabrics Enterprise Distribution (OFED) packages.
You only need to do this if you have installed any OFED packages on your system and you want to replace them with the latest OFED tools packages. The packages have to be removed manually, see Section 3.4, “Upgrading OFED Packages on Oracle Linux 6 Systems”.
To Switch a System to UEK R3:
Log in as root
on the system.
Change directory to /etc/yum.repos.d
.
# cd /etc/yum.repos.d
This assumes that yum on your system is
configured to find repository files in the default
/etc/yum.repos.d
directory.
Download the Oracle Linux 6 repository configuration file, http://public-yum.oracle.com/public-yum-ol6.repo.
For example:
# wget http://public-yum.oracle.com/public-yum-ol6.repo
The /etc/yum.repos.d
directory is updated
with the repository configuration file.
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 |
---|---|
| All packages released for Oracle Linux 6 (x86_64) including the latest errata packages. |
| Latest packages for Unbreakable Enterprise Kernel Release 3 for Oracle Linux 6.
Contains the |
| Latest OpenFabrics Enterprise Distribution (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.
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
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.
Reboot the system.
# shutdown -r now
If you have enabled the ol6_ofed_UEK
channel,
you must remove any existing OFED packages for the 32-bit x86
architecture before you can upgrade the remaining OFED packages
on your system. You must also completely remove and reinstall
the ibutils
packages. The latest version of
the ibutils
package no longer depends on an
ibutils-libs
package as the libraries are now
included in ibutils
itself.
Use the following command to remove any non-upgradable packages for the x86 architecture:
# rpm -e infiniband-diags \
libibcm \
libibcm-devel \
libibmad \
libibmad-devel \
libibumad \
libibumad-devel \
libibverbs \
libibverbs-devel \
libmlx4 \
librdmacm \
librdmacm-devel \
opensm-devel \
opensm-libs \
ibacm-devel
Use the following commands to remove the existing
ibutils
and ibutils-libs
packages and install the new ibutils
package:
#rpm -e ibutils ibutils-libs
#yum install ibutils