Patent ID: 7460383

Claim:
A storage apparatus connected to a host system, comprising: a nonvolatile memory for storing data sent and received from said host system; a disk device for storing data sent and received from said host system; a cache memory for temporarily storing data sent and received from said host system; a first control unit for controlling the reading and writing of said data from and into said nonvolatile memory; a second control unit for controlling the reading and writing of said data from and into said disk device; and a third control unit for controlling the reading and writing of said data from and into said cache memory; wherein said first, second and third control units are connected via a mutual network; said third control unit stores said data sent from said host system in said cache memory, and reads said data from said cache memory at a prescribed opportunity and sends it to said second control unit; said second control unit stores said data sent from said third control unit in said disk device and, when a prescribed condition is satisfied, reads said data from said disk device and sends it to said first control unit; and said first control unit stores said data sent from said second control unit in said nonvolatile memory.