Data storage has become an important issue for energy efficient data management in sensor networks. In this paper, we investigate the optimized storage placement problem in large scale sensor networks, aiming to achieve minimized energy cost. In order to efficiently deal with large scale deployment areas with irregular shape, we propose to utilize the hop as the computation unit instead of the node, such that computation complexity can be greatly reduced. We propose methodologies to solve the optimization problem both in situations for limited and unlimited numbers of storage units. The ultimate goal of this paper is to give fundamental guidance for optimized storage placement in large scale sensor networks. Simulation results show that our methodologies can greatly reduce the overall energy consumption compared to other strategies.