Oracle International Corporation

Steve Lee

Mahesh Baburao Girkar

Jiangbin Luo

Stephen John Vivian

George H Claborn

Juan R Loaiza

Raymond Guzman

Douglas Andrew Voss

Benedicto Elmo Garin, Jr

Nitin Karkhanis

Benedicto Garin

Hongjie Yang

Michael Harvey

Steven McGee

Robert McGuirk

Vinay H Srihari

Joydip Kundu

Richard James Anderson, Jr

Disclosed are methods and apparatuses to provide a redo repeater that allows for no data loss protection without the performance impact to the primary database even when a significant geographical distance separates the primary and standby databases. The Repeater is a lightweight entity that receives redo from the primary database with the purpose of redistributing that redo throughout the primary/standby system configuration. The Repeater able to extend no data loss protection and switchover functionality to terminal standby databases even though the primary database does not need to have a direct connection with those destinations.

Method and system for implementing a redo repeater

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.

Automatic failover configuration with lightweight observer

Techniques used in an automatic failover configuration having a primary database system, a standby database system, and an observer. 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 may use asynchronous transfer modes to transfer redo to the standby and permits automatic failover only when the observer is present and the failover will not result in data loss due to the asynchronous transfer mode beyond a specified maximum. 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.

Database system configured for automatic failover with user-limited data loss

A data recovery methodology with bound transaction data loss is described in which a database operator is allowed to set a bound that limits the number of transactions that can be lost. Transactions are placed in a buffer to be sent asynchronously to the standby system and synchronized based on the predetermined bound and on the number of transactions currently in the buffer.

Disaster recovery with bounded data loss

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Hollis, NH, United States of America

Steve Lee