3.2 About ULN Channels

ULN provides more than 100 unique channels, which support the i386, x86_64, and ia64 architectures, for releases of Oracle Linux 4 update 6 and later.

You can choose for your system to remain at a specific OS revision, or you can allow the system to be updated with packages from later revisions.

You should subscribe to the channel that corresponds to the architecture of your system and the update level at which you want to maintain it. Patches and errata are available for specific revisions of Oracle Linux, but you do not need to upgrade from a given revision level to install these fixes. ULN channels also exist for MySQL, Oracle VM, OCFS2, RDS, and productivity applications.

The following table describes the main channels that are available.

Channel

Description

_latest

Provides all the packages in a distribution, including any errata that are also provided in the patch channel. Unless you explicitly specify the version, any package that you download on this channel will be the most recent that is available. If no vulnerabilities have been found in a package, the package version might be the same as that included in the original distribution. For other packages, the version will be the same as that provided in the patch channel for the highest update level. For example, the ol6_arch_latest channel for Oracle Linux 6 Update 3 contains a combination of the ol6_u3_arch_base and ol6_u3_arch_patch channels.

_base

Provides the packages for each major version and minor update of Oracle Linux and Oracle VM. This channel corresponds to the released ISO media image. For example, there is a base channel for each of the updates to Oracle Linux 6 as well as for Oracle Linux 6. Oracle does not publish security errata and bugfixes on these channels.

_patch

Provides only those packages that have changed since the initial release of a major or minor version of Oracle Linux or Oracle VM. The patch channel always provides the most recent version of a package, including all fixes that have been provided since the initial version was released.

_addons

Provides packages that are not included in the base distribution, such as the package that you can use to create a yum repository on Oracle Linux 6.

_oracle

Provides freely downloadable RPMs from Oracle that you can install on Oracle Linux, such as ASMLib and Oracle Instant Client.

_optional

Provides optional packages for Oracle Linux 7 that have been sourced from upstream. This channel includes most development packages (*-devel).

Other channels may also be available, such as _beta channels for the beta versions of packages.

As each new major version or minor update of Oracle Linux becomes available, Oracle creates new base and patch channels for each supported architecture to distribute the new packages. The existing base and patch channels for the previous versions or updates remain available and do not include the new packages. The _latest channel distributes the highest possible version of any package, and tracks the top of the development tree independently of the update level.

Caution

You can choose to maintain your system at a specific update level of Oracle Linux and selectively apply errata to that level by subscribing the system to the _base and _patch channels and unsubscribing it from the _latest channel. However, for Oracle Linux 7, patches are not added to the _patch channel for previous updates after a new update has been released. For example, after the release of Oracle Linux 7 Update 1, no further errata will be released on the ol7_x86_64_u0_patch channel.

Oracle recommends that you keep you system subscribed to the _latest channel. If you unsubscribe from the _latest channel, your system will become vulnerable to security-related issues when a new update is released.