Red Hat OpenShift Service on AWS defaults to using an in-tree, or non-Container Storage Interface (CSI) plug-in to provision AWS EBS storage. In future Red Hat OpenShift Service on AWS versions, volumes provisioned using existing in-tree plug-ins are planned for migration to their equivalent CSI driver.
CSI automatic migration should be seamless. Migration does not change how you use all existing API objects, such as persistent volumes, persistent volume claims, and storage classes.
After full migration, in-tree plugins will eventually be removed in future versions of Red Hat OpenShift Service on AWS.