In the context of event processing, the term data persistence can be used to refer to several different things. A CEP engine will typically retain data in memory for use in processing future events. Aleri provides the option of disk-based persistence for retained data, which ensures that data is not lost in the event of a system failure or other shut-down scenario. Any retained data that has been configured for persistence will be restored when the system is restarted. This is also referred to as full state recovery since the system is fully restored to the state it was in before the shut-down or failure. Data persistence is also sometimes used to refer to the collection of data into an historical database, though this is not how Aleri uses the term.