OSCAR: an architecture for weak-consistency replication

An architecture for providing weak-consistency replication for databases in an internetwork is presented. It is designed to make the databases highly available and to operate reliably under difficult conditions, such as unreliable communication, low-bandwidth communication, network partitions, and host failures. Updates are stored in logs until they have been propagated to all database sites and properly delivered to the databases. A novel approach called mediation is used to provide integrated support for reliable replication and log purging. Other interesting features include requiring minimal support from database management systems, support of multiple weak-consistency methods, and easy tuning of the architecture's basic algorithms to particular environments.<>