A battery housing structure for portable devices includes a battery chamber and a movable seat located in a portable device. By collecting data associated with a library or library components and storing the collected data in a repository, the degradation of library components can be monitored and the reliability of library components determined, allowing unreliable components to be bypassed or replaced, enhancing the reliability of the library and preventing data loss. A fastener is configured to transfer a driving torque to the linking member when the fastener is rotatably driven into the link opening. The content thus selected is delivered to the user terminal. When the disk drive is stored in the receptacle, the second conduction portion comes into contact with the first conduction portion of the grounding metal member, thereby providing ground-connection between the disk drive and the housing. The present invention also relates to dynamic stage control.