Power Management in RAID Server Disk System Using Multiple Idle States

Energy efficient design for disk devices has become a very important issue, because ever increasing need for data storage systems significantly increases the power budget in the disk array. Most research on power management in disk devices focuses on the traditional way of stopping disk rotation. In this paper, we propose a new approach in which the energy consumption can be reduced without stopping the disk rotation. The proposed Multiple Idle States (MIS) model modulates the disk RPM to optimize the energy consumption during idle periods. We present a new threshold time model to calculate a minimum idle period so as to save energy without significant performance degradation. The simulation results with real traces show that our MIS achieves more than 58 % energy savings at low I/O workload and also gets 8 % energy savings for high workload with less than 50 % response time compared to the traditional shut-down power management scheme. 1