Three-state disk model for high quality and energy efficient streaming media servers

Energy conservation and emission reduction is an increasingly prominent and global issue in green computing. Among the various components of a streaming media server, the storage system is the biggest power consumer. In this paper, a Three-State Disk Model (3SDM) is proposed to conserve energy for streaming media servers without losing quality. According to the load threshold, the disks are dynamically divided into three states: overload, normal and standby. With the requests arriving and departing, the disk state transition among these three states. The purpose of 3SDM is to skew the load among the disks to achieve high quality and energy efficiency for streaming media applications. The load of disks in overload state will move to disks in normal state to improve the quality of service (QoS) level. The load of disks in normal state will be packed together to switch some disks into standby state to save energy. The key problem here is to identify the blocks that need migrating among disks. A sliding window replacement (SWR) algorithm is developed for this purpose, which calculates the block weight based on the request frequency falling within the window of a block. Employing a validated simulator, this paper evaluates the SWR algorithm for conventional disks based on the proposed 3SDM model. The results show that this scheme is able to yield energy efficient streaming media servers.