Chapter 2. OpenShift Container Storage upgrade channels and releases
In OpenShift Container Platform 4.1, Red Hat introduced the concept of channels for recommending the appropriate release versions for cluster upgrades. By controlling the pace of upgrades, these upgrade channels allow you to choose an upgrade strategy. As OpenShift Container Storage gets deployed as an Operator in OpenShift Container Platform, it follows the same strategy to control the pace of upgrades by shipping the fixes in multiple channels. Upgrade channels are tied to a minor version of OpenShift Container Storage. For example, OpenShift Container Storage 4.6 upgrade channels recommend upgrades from 4.5 to 4.6 and upgrades within 4.6. They do not recommend upgrades to 4.7 or later releases. This strategy ensures that administrators can explicitly decide to upgrade to the next minor version of OpenShift Container Storage.
Upgrade channels control only release selection and do not impact the version of the cluster that you install; the
ocs-operator decides the version of OpenShift Container Storage to be installed. Out of the box, it always installs the latest OpenShift Container Storage release maintaining the compatibility with OpenShift Container Platform. So on OpenShift Container Platform 4.6, OpenShift Container Storage 4.6 will be the latest version which can be installed.
OpenShift Container Storage upgrades are tied to the OpenShift Container Platform upgrade to ensure that compatibility and interoperability are maintained with the OpenShift Container Platform. For OpenShift Container Storage 4.6, OpenShift Container Platform 4.5, 4.6 and 4.7 are supported. OpenShift Container Platform 4.5 and 4.7 is supported to maintain backward and forward compatibility with OpenShift Container Platform. Keep the OpenShift Container Storage version the same as OpenShift Container Platform in order to get the benefit of all the features and enhancements in that release.
OpenShift Container Platform 4.6 offers the following upgrade channels:
eus-4.6(only available when running 4.6)
- stable-4.6 channel
Once a new version is Generally Available, the stable channel corresponding to the minor version gets updated with the new image which can be used to upgrade. You can use the
stable-4.6channel to upgrade from OpenShift Container storage 4.5 and upgrades within 4.6.
- eus-4.6 channel
In addition to the stable channel, certain minor versions of OpenShift Container Platform offer Extended Update Support (EUS). These EUS versions extend the maintenance phase for customers with Premium Subscriptions to 14 months. OpenShift Container Storage 4.6 is currently the only minor version with EUS.
Although there is no difference between stable-4.6 and eus-4.6 channels until OpenShift Container Platform 4.6 transitions to the EUS phase, you can switch to the EUS channel as soon as it becomes available. When OpenShift Container Platform 4.6 transitions to the EUS phase of its lifecycle, the stable-4.6 channel will no longer receive subsequent z-stream updates. After you upgrade to a version that is exclusive to the EUS channel, that cluster will no longer be eligible for minor version upgrades until upgrades to the next EUS version become available. The next planned EUS version is to be 4.10 and the upgrade to that version will require a serial set of version upgrades, such as from 4.6 to 4.7 to 4.8 to 4.9 to 4.10.
Additionally, you may only switch to the EUS channel when your cluster is running a supported version of OpenShift Container Platform 4.6.
Finally, if you install a 4.6 version that is exclusive to EUS, you will similarly not be able to upgrade to a later minor version until upgrades are provided to 4.10.