Design and simulation of a hybrid replication control protocol

Replica control protocols in distributed database systems are responsible for the management and maintenance of replicated (redundant) data. Maintaining replicated data improves performance and increases availability. Keeping the replicated data consistent and available during the presence of failures can however become quite difficult. This paper presents the design of a hybrid replica control protocol that attempts to maximise availability and minimise communication overhead, by combining the advantages of two common replica control protocols into one. The protocol was simulated using SimJava, a process-based discrete event simulation package. The results from the simulations showed that not only did the hybrid algorithm maintain a high level of availability, it did so while minimising communication overheads.