DomU OS Patching is a feature which enables ExaCS customers to upgrade the Exadata OS image on their domU nodes in an automated manner from their OCI console and APIs. The following information explains about a recent change in the feature that could not be added to the docs in time for release, but will be added soon.

Rollback required if the patch fails.

On multi-node systems, if one of the nodes fails the patch, you must roll back all nodes to get them all on the same version.  Then run precheck, fix any problems, and run the patch again.  

Example:  If you run precheck on Monday and all nodes pass, but do not apply the patch until Wednesday, it is possible that one or more of the nodes may fail the patch because of changes on the nodes or a maintenance conflict.

To prevent this from happening, Oracle recommends that you run precheck right before applying the patch.

For more information, see Updating an Exadata Cloud Service VM Cluster Operating System.