A server containing hard disk modules which can be slid into place and which allow connection at the front and at the rear of a housing. The server includes the housing which defines an opening, the hard disk modules, and a plurality of trays. Receiving channels communicating with the opening are defined in the housing, the receiving channels are isolated and arranged side by side and each channel can receive one tray. A hard disk module is positioned in one tray, a front end and a rear end of the housing defines front connection port and rear connection port for cable connections to each hard disk module.