An Energy Saving Scheme on Storage Systems for Video Delivery Services

In recent years, large scale computational resources are required to manage huge volume of data. However, their energy consumption is increasing year by year, thus performance of energy saving is paid much attention today. Storage systems are energy consuming devices in computers, so energy saving in storage systems is important. In this paper, we propose an energy saving scheme on storage systems for video delivery services. A conventional approach to reduce energy consumption is stopping rotation of disks while HDDs are not accessed. But, it brings increase of access delays, because restarting disk rotation needs 10 - 30 seconds. To solve this problem, we consider both data placement based on data popularity and prefix caching. Popular video files are located on HDDs never stopped, and unpopular video files are located on stoppable HDDs. Instead of unpopular video files, we locate prefix caches, which contain initial frames of the video files, on non-stop HDDs. When a video file in a stopped HDD is requested, prefix cache is used instead of the original video file until disk rotation restarts. We show efficiency of our scheme in our simulation experiment.