Perform a phased upgrade VCS to minimize the downtime for the cluster that you want to upgrade. Depending on the situation, you can calculate the approximate downtime as follows:
You can fail over all your service groups to the nodes that are up.
Downtime equals the time that is taken to offline and online the service groups.
You have a service group that you cannot fail over to a node that runs during upgrade.
Downtime for that service group equals the time that is taken to perform an upgrade and restart the node.
