A system is provided for automatically closing a server-rack door. A microphone acquires sound data and an acceleration sensor acquires acceleration data. A controller determines at least one time when a volume of the sound data exceeds a threshold. The controller identifies at least one waveform from the acceleration data which matches (i) an opening waveform or (ii) a closing waveform. The controller checks, for each given waveform from among the at least one waveform, if the at least one time is within a time range of the given waveform and, if so, determine that the user is opening or closing the server-rack door by identifying the given waveform as matching the opening or closing waveform. The controller provides a notification of an open status of the server-rack door based on numbers of opening and closing waveforms. The controller automatically closes the server-rack door, responsive to the notification.