Unbreakable Enterprise Kernel Release 3

Fast, Modern, Reliable, Optimized for Oracle

The Unbreakable Enterprise Kernel Release 3 is Oracle's third major release of its heavily tested and optimized operating system kernel for Oracle Linux 6, x86_64 platforms..

The Unbreakable Enterprise Kernel Release 3 is based on the mainline Linux kernel version 3.8.13 and boasts a wide range of new features and improvements relevant for enterprise workloads.

Testing of the Oracle Unbreakable Enterprise Kernel includes both the operating system and the full Oracle application stack running on top of it, verifying stability and correct behavior in all situations. The test suite includes installation, functional, stress and destructive tests, which are executed under varying workloads (e.g. I/O or CPU intensive), with various database sizes. Several parameters are varied during the full run of the test suites, which also include crash scenarios in Oracle Real Application Cluster configurations.

Some of the key features and changes in this release include:

Dtrace Dtrace provides Oracle Linux customers with a comprehensive, dynamic tracing framework.  Beginning with Release 3, customers will no longer be required to boot into a separate kernel to use Dtrace because it has now been fully integrated into the kernel.  This release also includes user-space statically defined tracing (USDT) support, which provides support for SDT-like probes in userspace executables and libraries.
Performance and Scalability Improvements

The Linux kernel was improved and refined in many areas to perform better and faster on systems with many CPUs and large amounts of main memory. This includes improvements to the scheduler, memory management, file system layers and the networking stack.

Btrfs Improvements Continued improvements in scalability, performance and stability for Btrfs are key features of this latest release.  With new features such as send/receive, administrators can easily compare the differences between two subvolumes which can be used as an efficient incremental backup mechanism.  New support for subvolume-aware quota groups (qgroups) allow administrators to set different size limits for a volume and its subvolumes.  The file hole punching features, allows a user to mark a portion of a file as unused, freeing up the associated storage.
Virtualization Improvements The Unbreakable Enterprise Kernel Release 3 includes the latest virtualization innovations from the upstream kernel community for running Oracle Linux as a guest VM in both para-virtualized and hardware-virtualized configurations. This release also includes support for Windows server 2008 and 2008 R2 Hyper-V paravirtualized drivers, allowing Oracle Linux to easily run as a virtual guest under Windows Hyper-V.
Linux Containers Linux Containers (LXC) are now fully supported with Unbreakable Enterprise Kernel Release 3.  LXC utilize cgroups to safely and securely run multiple applications or instances of an operating system on a single host in an isolate fashion without the overhead of traditional virtualization solutions.  LXC allow a direct and defined distribution of system resources like CPU and I/O which offers the best possible performance and flexibility in managing the resources available on a system.
TCP Fast Open TCP fast open (TFO) is a new feature which accelerates the opening of successive TCP connections between two points through the elimination of one rount time trip (RTT) from certain TCP transactions.  This feature has been shown to dramatically improve performance  for certain web transactions.
OFED 2.0 and RDS Updates to OpenFabrics Enterprise Distribution (OFED) bring new networking stack features to Release 3 of the Unbreakable Enterprise Kernel.  Protocols supported in this release include:
  • Ethernet over InfiniBand (EoIB)
  • IP encapsulation over InfiniBand (IPoIB)
  • Ethernet tunneling over IPoIB (eIPoIB)
  • SCSI RDMA Protocol (SRP)
  • iSCSI Extensions for remote direct memory access (iSER)
  • Reliable Datagram Sockets (RDS)
  • Sockets Direct Protocol (SDP)
File System Improvements With this release several updates have been made to key file systems such as NFS, XFS and Ext4.
  • NFS 4.1 client support now includes support for sessions, directory delegations and parallel NFS (pNFS) as defined in RFC 5561
  • Ext4 now stores quota files in hidden inodes as file system metadata instead of separate files in the file system
  • XFS journals now leverage checksums for verifying log integrity
Updated Drivers and Hardware Support Many of the key device drivers included in mainline Linux were updated to newer versions in close cooperation with our hardware partners. In addition to device driver updates, this release introduces support for the Intel Ivy Bridge (IVB) processor family.

Technology Previews

In addition to the features listed above, the Unbreakable Enterprise Kernel includes the following features which are still under development, but are made available for testing/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 crypographic 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.