Power Conservation Strategies for MEMS-Based Storage Devices

Power dissipation by storage systems in mobile computers accounts for a large percentage of the power consumed by the entire system. Reducing the power used by the storage device is crucial for reducing overall power consumption. A new class of secondary storage devices based on microelectromechanical systems (MEMS) promises to consume an order of magnitude less power with 10–20 times shorter latency and 10 times greater storage densities. We describe three strategies to reduce power consumption: aggressive spin-down, sequential request merging, and subsector accesses. We show that aggressive spin-down can save up to 50% of the total energy consumed by the device at the cost of increased response time. Merging of sequential requests can save up to 18% of the servicing energy and reduce response time by about 20%. Transferring less data for small requests such as those for metadata can save 40% of the servicing energy. Finally, we show that by applying all three power management strategies simultaneously the total power consumption of MEMS-based storage devices can be reduced by about 54% with no impact on I/O performance.