Authors: Manu Vardhan, Shrabani Mallick, Shakti Mishra, D. S. Kushwaha
Cloud computing has been coined as a “buzz” word to describe on-demand computing services. It not only promises reliable services delivered through next-generation data centers that are built on compute and storage virtualization technologies but also addresses the key issues such as scalability, reliability and fault tolerance. The one way to achieve this is through service replication across different machines. Though replication potentially improves fault tolerance, it leads to the problem of ensuring consistency of replicas when certain service is updated or modified. However, fewer replicas also decrease concurrency and the level of service availability. A balanced synchronization between replication mechanism and consistency not only ensures highly reliable and fault tolerant system but also improves system performance significantly. This paper presents a threshold based service replication model that creates or migrate a replica to other servers on the basis of number of service accesses. To fulfill the demand in constant time O(k), Bloom Filter with Hashing based approach is used to locate the file on the server. The simulation results indicate that proposed model reduces the number of messages exchanged for service replication by 33-55% and 25-50%, thus improving the system performance significantly.
Keywords: component; Service Replication, Consistency, File Replication Server, Request-Reply Protocol