Energy-aware data prefetching for multi-speed disks in video servers

Energy consumption is an important issue in data centers, and disks use a significant proportion of the total energy. A promising approach to reducing disk energy consumption is to use multi-speed disks with lower rotational speeds. But changing the speed requires a significant time, which reduces the number of viable opportunities to decrease the disk speed. We propose a new energy-aware data prefetching scheme for multi-speed disks in video servers. We start by examining the power and performance characteristics of multi-speed disks. We then analyze the disk bandwidth and buffer requirements needed for jitter-free speed transitions and propose a new data prefetching scheme to extend the time that disks stay at low speed. The effectiveness of the proposed scheme is evaluated through simulations.