Database system configured for automatic failover with no data loss
First Claim
1. An automatic failover configuration comprising:
- participants includinga primary database system that processes transactions and produces redo data therefor,a standby database system that receives the redo data via a communications link, andan observer,each participant including a processor that has access to memory; and
system state specifiers in the memory, the system state specifiers including a synchronized system state specifier that prevents divergence resulting from a lack of synchrony between the primary database system and the standby database system with regard to the redo data at the time of an automatic failover andthe system state specifiers preventing the automatic failover from resulting in divergence of the database systems while permitting the primary database system to continue to process redo data when both the observer and the standby database system are absent as long as the observer and the standby database system became absent sequentially.
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Accused Products
Abstract
Techniques used in an automatic failover configuration having a primary database system, a standby database system, and an observer for preventing divergence among the primary and standby database systems while increasing the availability of the primary database system. In the automatic failover configuration, the primary database system remains available even in the absence of both the standby and the observer as long as the standby and the observer become absent sequentially. The failover configuration further permits automatic failover only when the observer is present and the standby and the primary are synchronized and inhibits state changes during failover. The database systems and the observer have copies of failover configuration state and the techniques include techniques for propagating the most recent version of the state among the databases and the observer and techniques for using carefully-ordered writes to ensure that state changes are propagated in a fashion which prevents divergence.
46 Citations
20 Claims
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1. An automatic failover configuration comprising:
- participants including
a primary database system that processes transactions and produces redo data therefor, a standby database system that receives the redo data via a communications link, and an observer, each participant including a processor that has access to memory; and system state specifiers in the memory, the system state specifiers including a synchronized system state specifier that prevents divergence resulting from a lack of synchrony between the primary database system and the standby database system with regard to the redo data at the time of an automatic failover and the system state specifiers preventing the automatic failover from resulting in divergence of the database systems while permitting the primary database system to continue to process redo data when both the observer and the standby database system are absent as long as the observer and the standby database system became absent sequentially. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- participants including
Specification