A Hybrid Protocol for Replicas Management in Data Grid

In large scale distributed systems, replication is a popular technique for improving the accessibility of information and surviving the unreliability of communication networks. Pessimistic replication and optimistic replication are two contrasting replication models. They represent the two extremes in the availability-consistency. Pessimistic replication favors consistency over availability, while optimistic replication favors availability over consistency. With an aim of benefiting from the advantages of the two approaches Pessimistic and Optimistic, this article proposes a hybrid approach inspired by the two preceding ones, whose objective is double vacation, because it initially makes it possible to reduce response times compared to a completely Pessimistic approach and in the second time to improve the quality of services compared to an overall Optimistic. The results of simulation obtained are very satisfactory, and that the approach is very promising for the application requiring a certain quality of service and a acceptable response time.