Patent ID: 7398367

Claim:
A storage system comprising: a plurality of controllers, wherein each controller comprises: a port, connected to a plurality of host computers via a fibre channel network, for receiving first data transferred from said host computers, a port controller, connected to said port, for controlling said port, and a cache memory, connected to said port controller, for temporarily storing data and control information, wherein said port controller receives said first data from said host computers via said port, sends second data via said port to an external storage system connected to said port via said fibre channel network, and executes receiving said first data and sending said second data in a time-sharing manner, wherein said port controller executes an initiator task and a target task, said initiator task is executed to send an access request to another storage system, said target task is executed to make response to an access request received from said host computers, and wherein requests to execute said target task and requests to execute said initiator task are stored in said cache memory as said control information, requests to execute said target task is stored according to said access request from said host computers, requests to execute said initiator task is stored according to a request to send said second data to said external storage system, said port controller executes said target task and said initiator task in time-sharing manner according to said control information.