A terminal, wherein the terminal comprises: • a body comprising a hard disk slot disposed in the body for accommodating a hard disk, • a cover body detachably mounted on the body, • a circuit board mounted in the body, • a central processing unit welded on the circuit board, • a control rod being a rod body mounted on an inner surface the cover body, wherein the inner surface is a surface of the cover body facing an interior of the body when the cover body is mounted on the body, • a touch switch welded on the circuit board, • a door interlock switch, wherein the door interlock switch comprises a locker mounted on a surface of the cover body and a lock cylinder that is mounted on the body and that is opposite to the locker, • wherein in a first state in which the cover body is mounted on the body and the cover body and the body are used together to seal the hard disk in the hard disk slot, an end part of the control rod is in contact with the touch switch, but does not trigger the touch switch, so that in the first state the touch switch is in a closed state, and the door interlock switch is configured and arranged to lock and keep the cover body on the body and the locker is engaged with the lock cylinder, • wherein in a second state in which the cover body is to be detached from the body, the cover body is configured and arranged to drive the control rod to press the touch switch, thereby opening the touch switch, and after detecting, by the central processing unit, an electrical signal variation due to opening of the touch switch, the central processing unit is configured to instruct the hard disk to perform data protection and to power off the hard disk and furthermore in the second state the cover body is configured and arranged to drive the locker to press the locker against the lock cylinder, thereby disengaging the locker from the lock cylinder. • a body comprising a hard disk slot disposed in the body for accommodating a hard disk, • a cover body detachably mounted on the body, • a circuit board mounted in the body, • a central processing unit welded on the circuit board, • a control rod being a rod body mounted on an inner surface the cover body, wherein the inner surface is a surface of the cover body facing an interior of the body when the cover body is mounted on the body, • a touch switch welded on the circuit board, • a door interlock switch, wherein the door interlock switch comprises a locker mounted on a surface of the cover body and a lock cylinder that is mounted on the body and that is opposite to the locker, • wherein in a first state in which the cover body is mounted on the body and the cover body and the body are used together to seal the hard disk in the hard disk slot, an end part of the control rod is in contact with the touch switch, but does not trigger the touch switch, so that in the first state the touch switch is in a closed state, and the door interlock switch is configured and arranged to lock and keep the cover body on the body and the locker is engaged with the lock cylinder, • wherein in a second state in which the cover body is to be detached from the body, the cover body is configured and arranged to drive the control rod to press the touch switch, thereby opening the touch switch, and after detecting, by the central processing unit, an electrical signal variation due to opening of the touch switch, the central processing unit is configured to instruct the hard disk to perform data protection and to power off the hard disk and furthermore in the second state the cover body is configured and arranged to drive the locker to press the locker against the lock cylinder, thereby disengaging the locker from the lock cylinder.