High-density system having a plurality of system units

摘要

A high-density system includes a plurality of system units. Each system unit includes a backplane and a plurality of central processing unit (CPU) cards plugged into the backplane. Each backplane has a servicing input/output (I/O) bus for carrying servicing I/O data. Each central processing unit (CPU) card is plugged into the corresponding backplane and capable of accepting data from the servicing I/O bus or sending data to the servicing I/O bus. The high-density system further includes at least one cable for connecting the servicing I/O busses of the system units so as to transfer the servicing I/O data, and a servicing control system. The servicing control system includes a switching system for selectively connecting only one of the CPU cards in the high-density system to the servicing I/O bus, and an I/O interface module electrically connected to the servicing I/O bus. The I/O interface module has at least a port to which an external device may be plugged. The servicing control system selectively enables only one of the CPU cards in the high-density system to send servicing I/O data to the port or to receive servicing I/O data from the port.