Patent ID: 8103635

Claim:
An automatic failover configuration comprising: participants including one or more servers having one or more memories, comprising: a database system that has newly become a primary database system in the automatic failover configuration, the primary database system having a first database, processing transactions on the first database and producing first redo data therefor, in which the primary database system became the primary database system as a result of a failover after a former primary database system became absent; and an unreinstated database system having a second database, in which the unreinstated database system is the former primary database system; a reinstatement descriptor in the primary database system that controls reinstatement of the unreinstated database system as a standby database system in the automatic failover configuration, the reinstatement descriptor being automatically made in the primary database system upon occurrence of a reinstatement event, in which the reinstatement descriptor includes a specification of a redo divergence point in second redo data in the unreinstated database system, the redo divergence point being a point such that when the second database is restored no further than to the divergence point and the first redo data is then applied to the restored second database, the second database does not diverge from the first database; a first reinstater in the primary database system that propagates the reinstatement descriptor to the unreinstated database system; and a second reinstater in the unreinstated database system that uses the reinstatement descriptor to automatically reinstate the unreinstated database system by restoring the second database such that when the first redo data is applied after reinstatement to the restored second database, the second database does not diverge from the first database, in which the automatic failover configuration permits failovers wherein the primary database system after the failover has a data loss relative to the former primary database system and when a failover with data loss has occurred, the redo divergence point specifies a point in the second redo data such that when the second database is restored no further than to the divergence point and reinstated database system then applies the first redo data to the second database, the second database also has the data loss.