Chapter 5. OpenShift Data Foundation upgrade overview

OpenShift Data Foundation recognizes two types of upgrades: Z-stream release upgrades and Minor Version release upgrades. While the user interface workflows for these two upgrade paths are not quite the same, the resulting behaviors are fairly similar. The distinctions are as follows:

For Z-stream releases, OCS will publish a new bundle in the redhat-operators CatalogSource. The OLM will detect this and create an InstallPlan for the new CSV to replace the existing CSV. The Subscription approval strategy, whether Automatic or Manual, will determine whether the OLM proceeds with reconciliation or waits for administrator approval.

For Minor Version releases, OpenShift Container Storage will also publish a new bundle in the redhat-operators CatalogSource. The difference is that this bundle will be part of a new channel, and channel upgrades are not automatic. The administrator must explicitly select the new release channel. Once this is done, the OLM will detect this and create an InstallPlan for the new CSV to replace the existing CSV. Since the channel switch is a manual operation, OLM will automatically start the reconciliation.

From this point onwards, the upgrade processes are identical.

When the OLM detects an approved InstallPlan, it begins the process of reconciling the CSVs. Broadly, it does this by updating the operator resources based on the new spec, verifying the new CSV installs correctly, then deleting the old CSV. The upgrade process will push updates to the operator Deployments, which will trigger the restart of the operator Pods using the images specified in the new CSV.

At this point, the reconciliation of the OpenShift Data Foundation operands proceeds as defined in the OpenShift Data Foundation installation overview. The operators will ensure that all relevant resources exist in their expected configurations as specified in the user-facing resources (for example, StorageCluster).