1. A method of reinstating an unreinstated database system which has become unreinstated as a result of a reinstatement event in a failover configuration, the method comprising: receiving a reinstatement descriptor from a primary database system, the primary database system having made the reinstatement descriptor in response to the reinstatement event; and performing the reinstatement as indicated by the reinstatement descriptor on a database of the unreinstated database system, in which the reinstatement descriptor specifies a redo divergence point in a redo data of the unreinstated database system.