Deadlock is avoided in a grid storage system having superior scalability. Provided is a storage subsystem connected to a host computer for receiving a write or read access from the host computer. This storage subsystem includes a plurality of modules respectively having a storage resource, a switch for connecting the plurality of modules, a controller for controlling the transfer of a packet based on the write or read access from the host computer to a target module among the plurality of modules via the switch, and a memory storing a transfer rule of the packet. The controller controls the transfer of the packet based on the transfer rule.