A Utility-Based Data Replication Algorithm in Large Scale Data Grids

Data grids support access to widely distributed storage for large numbers of users accessing potentially many files. To enhance access time, replication at nearby sites may be used. Data replication, a technique much investigated by data grid researchers in past years creates multiple replicas of file and places them in conventional locations to shorten file access times. One of the problems in data replication is creation of replicas, replica placement and replica selection. Dynamic creation of replicas in an appropriate site by data replication strategy can increase the systems performance. In this paper, we propose a data replication algorithm, called the Utility-base Data Replication (UDR) algorithm that improves file access time. Each grid site has its own capabilities and characteristics; therefore, choosing one specific site from many sites that have the needed data is a key and significant decision. The replica selection problem has been studied by many researchers who only considered response time as a criterion for the selection process. Therefore, in this study, we addressed the problem of how to select the best replica for the users' jobs. Our approach is simulated using a data grid simulator, OptorSim, developed by European Data Grid projects. Comparing to the previous work the experimentation shows the improvement in the overall performance.