One of the more important traits of a good home server is low power consumption. Hard drives can account for a big chunk if not the majority of power usage of a home server depending on the number of drives. Most hard drives can be put into sleep or stand-by mode to reduce power usage dramatically. Western Digital drives require a more forceful method which is where hd-idle tool comes into play. Hd-idle is a simple tool that can force both SATA and USB hard disk devices into stand-by mode.