The main software channel for an Oracle Linux release is termed a base (or parent) software channel. You can associate a number of child software channels with the base software channel. Each child software channel usually provides packages that are not available with the base software channel. If multiple versions of a package exist in different subscribed channels, yum versioning and dependency resolution ensure that the most up-to-date version of a package is installed.

You can subscribe a client to a single base channel and its child channels. For channels that are not specific to an update, such as addons, you can create an addons child channel for each update-level base channel and associate this child channel with the same addons repository.

If you set up Spacewalk to obtain Oracle Linux packages from ULN, Oracle recommends that you configure a separate olN_arch_un_base base software channel and olN_arch_un_patch child software channel for each update of Oracle Linux as it becomes available. This keeps the software channels small and helps to speed up channel cloning. Client systems are not upgraded across update levels unless you either change the source channel used for channel cloning or reconfigure the channels to which a client system subscribes.

The following example illustrates a typical configuration of the base and child software channels for Oracle Linux, where the base and patch channels are synchronized with ULN:

oraclelinux7-x86_64-base
 |-- oraclelinux7-x86_64-addons
 |-- oraclelinux7-x86_64-ksplice
 |-- oraclelinux7-x86_64-optional
 |-- oraclelinux7-x86_64-patch
 |-- oraclelinux7-x86_64-spacewalk22-client
 |-- oraclelinux7-x86_64-uek-r3

The Oracle Linux yum server provides a public_olN_latest channel, which includes all packages for an entire Oracle Linux release. As individual patch channels for each update are not available, configure the base software channel to use the public_olN_latest channel. You can use the spacewalk-common-channels utility to configure the software channels, repositories, GPG keys, and activation keys for Oracle Linux 5, Oracle Linux 6, and Oracle Linux 7. See Section 2.3, “Configuring Software Channels to Obtain Packages from the Oracle Linux Yum Server”.

The following example illustrates a typical configuration of the base and child software channels for Oracle Linux, where the base channel is synchronized with the public_ol7_latest channel on the Oracle Linux yum server:

oraclelinux7-x86_64-latest
 |-- oraclelinux7-x86_64-addons
 |-- oraclelinux7-x86_64-optional
 |-- oraclelinux7-x86_64-spacewalk22-client
 |-- oraclelinux7-x86_64-uek-r3