You can upgrade the server components using the Rolling Upgrade wizard. Rolling upgrade minimizes the cluster downtime as compared to the parallel upgrade.

During rolling upgrade, the wizard identifies the passive nodes and the application service group dependency. Depending on this information the wizard generates an upgrade plan, such that the passive nodes are upgraded first. After the passive nodes are upgraded, the service groups failover to these upgraded nodes. The passive nodes now become the active nodes and the active nodes are now the passive nodes. After the service groups failover, the wizard upgrades the new passive nodes.