Hard Disk Drive Advanced Power Management (APM)
The advanced power management appeared as an option in the hard disk drives supporting ATA/ATAPI-4 or higher standard. Change of its value from 1 to 254 allows to regulate the performance of the hard disk drive and, thereby, to save energy of power supplies. Value less than 128 enables the hard disk drive to stop the spindle motor without any commands during certain period time, which allows saving as much energy of the power supply as possible, but leads to the increased deterioration of kinematics and the delay at the waking caused by waiting of magnetic disks spinning up to the necessary speed. The work of the advanced power management implemented in the hard disk drives does not depend on the "sleep" timer of the operating system.