This figure shows the upgrade of two middle tiers and an associated Infrastructure in four stages. In the first stage, both middle tiers and the Infrastructure are stopped and in a pre-upgrade state (Release 2 (9.0.2) or Release 2 (9.0.3)). In the second stage, one middle tier is upgraded to Release 2 (9.0.4) and started. In the third stage, both middle tiers are at Release 2 (9.0.4) and started. Finally, in the fourth stage, the middle tiers and Infrastructure are upgraded to Release 2 (9.0.4) and started.