The Retirement phase defines the activities executed to remove a system (or an older release of the system) from your production environment.
Retirement of a system can be a complex endeavor that is often treated as a project in its own right.
Systems can be retired all at once or piecemeal over time.
It is often useful to run new and old systems in parallel for a length of time to ensure that the new system is operating properly.
Retirement efforts are often executed in conjunction with the implementation of systems that replace them; they must be coordinated closely.
The final phase of the EUP lifecycle is the Retirement phase, depicted in Figure 5-1. The goal of this phase is the removal of a system release ...