Internal hard disc drive scalability using mezzanine backplane technology

A split backplane is used in a network server, thereby permitting the use of more than one channel to connect a server motherboard to one or more hard disc drives. A master card 'A' is plugged into each backplane. In turn, one or more additional cards may be stacked parallel to the master card, being joined thereto by a mezzanine connector. The additional card can be another master card 'A' or a slave card 'B' that performs subordinate functions. Each card is coupled to one or more hard disc drives through a multiple pin connector to transmit SCSI, or similar signals. The 'A' and 'B' cards are arranged generally parallel with the planar surfaces of the disc drives so as to improve the flow of cooling air as it is drawn through the enclosure or mounting rack past the disc drives.