Formal Development of Fault-Tolerant Majority Based Replica Control Protocol using Event-B

In distributed environment, data availability and concurrency control both are challenging issues. Data availability can be maintained by replicating data at several locations or sites that will improve the availability but at the same time it is very challenging task to maintain the consistency of it. In order to improve the performance of the system, it is required to execute multiple transactions concurrently on several sites. Therefore, we need to control these concurrent transactions for maintaining consistency of replica. Replica control become more complex for the environment where messages are delayed due to communication failure. In this paper, we develop formal model of fault-tolerant replica control protocol Using Event-B. Formal methods are mathematical techniques through which we can verify the correctness of model. Event-B is a formal method which is used to develop the model in distributed environment.

A HIGH AVAILABILITY CLUSTER-BASED REPLICA CONTROL PROTOCOL IN DATA GRID

Data replication is widely used to provide high data availability, and increase the performance of the distributed systems. Many replica control protocols have been proposed in distributed and grid environments that achieved both high performance and availability. However, the previously proposed protocols still require a bigger number of replicas for read and write operations which are not suitable for a large scale system such as data grid. In this paper, a new replica control protocol called Clusteringbased Hybrid (CBH) has been proposed for managing the data in grid environments. We analyzed the communication cost and data availability for the operations and compared CBH protocol with recently proposed replica control protocols called Dynamic Hybrid (DH) protocol and Diagonal Replication in 2D Mesh (DR2M) protocol. To evaluate CBH protocol, a simulation model was implemented using Java. Our results show that for the read operations, CBH protocol improves the performance of communication cost and data availability compared to the DH and DR2M protocols.