The invention relates to exchanging micro programs in a storage device, automatically, without halting operation. In one embodiment, the path adapters of a host computer are connected to the input/output ports of respective clusters of a storage device, by respective connection paths. Path switching software is provided in the host computer, as well as database indicating connection destinations of the connection path. In the storage device, the input/output ports are connected to a group of a plurality of hard disk drive devices. An internal management device, and a database indicating the connection destination of each input/output port, are provided in the storage device. The management server device is connected to a host computer and a storage device, via a LAN, and a program exchanging program and micro programs to be used in exchange are provided in this management server device. Instructions for invoking the program are issued from the computer.