Online Grid Replication Optimizers to Improve System Reliability

In a data intensive grid system, many data replica schemes and models have been proposed to improve the system response time or data consistency, but little attention has been paid to the system reliability. In this paper, we investigate how these data replica schemes impact the system reliability. We use several metrics of system reliability we previously proposed (system bytes missing rate and system file missing rate), and we model the system availability problem assuming limited replica storage and different sized files. In order to achieve higher system data availability, in this paper we propose two new replica optimizers, MinDmr-beta and MinDmr-gamma, to minimize the data miss rate (MinDmr). A comparison of our replica optimizers using a simulation on the OptorSim demonstrates that by utilizing our strategy, we can increase the data availability for files with different sizes.