Efficient availability mechanisms in distributed database systems
Bharat Bhargava, Sumi Helal · 1993
The resiliency of distributed database systems can be realized through a collection of integrated faulttolerance mechanisms.These include clata replication techniques, failure detection, failure isolation through reconfiguration and adaptability, and non-blocking atomic commitment.Collectively, these mechanism enhance the availability and operability of the syste]n in the presence of various types of site and communication failures.In this paper, we focus on mechanisms for data replication, failure detection, and reconfiguration.We present the implementation details of each of these mechanisms along with their integration within the RAID system developed at Purdue.Data replication is implemented through the partial replication of data relations, and through the use of a library of replication control methods.An on-line replication control server (RC) provides highly available database operations through the adaptable use of these methods.Failuredetection isirriplementedvi aa reliable surveillance facility that rnonitorsthe changes in system connectivity.Such failures include site and communication failures as well as network partition.Repairs andnetwork merges are also detected by this facility, thus leading to the automatic initiation of recovery.We wilI show how failure isolation is achieved through data and server reconfiguration and by the adaptable use of replication methods.