This application discloses a storage system, a storage device, and a hard disk drive scheduling method. The storage system includes M disk groups, a power supply system, and a controller, and M is a natural number not less than 3. Each of the M disk groups includes at least one hard disk drive. The controller is configured to control a hard disk drive in a first disk group of the M disk groups to be in an active state to process a first group of service requests, and control a hard disk drive in a second disk group of the M disk groups to switch from the inactive state to a spin up state when the hard disk drive in the first disk group is in the active state.