When new versions of OpenShift are released, you can upgrade your existing cluster to apply the latest enhancements and bug fixes. This includes upgrading from previous minor versions, such as release 3.0 to 3.1, and applying asynchronous errata updates within a minor version (3.1.z releases). See the OpenShift Enterprise 3.1 Release Notes to review the latest changes.
Due to the core architectural changes between the major versions, OpenShift Enterprise 2 environments cannot be upgraded to OpenShift Enterprise 3 and require a fresh installation.
Unless noted otherwise, node and masters within a major version are forward and backward compatible, so upgrading your cluster should go smoothly. However, you should not run mismatched versions longer than necessary to upgrade the entire cluster.
If you installed using the quick or advanced installation and the ~/.config/openshift/installer.cfg.yml or inventory file that was used is available, you can perform an automated upgrade. Alternatively, you can upgrade OpenShift manually.