Storage apparatus, controller and control method

A controller for controlling a storage apparatus connected to a host system, comprising:

• a first control unit for controlling the reading and writing of data from and into a nonvolatile memory storing said data to be sent and received from said host system;
• a second control unit for controlling the reading and writing of data from and into a disk device storing data to be sent and received from said host system;
• and
• a third control unit for controlling the reading and writing of data from and into a cache memory temporarily storing said data to be sent and received from said host system;
• 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.

A control method of controlling a storage apparatus connected to a host system;

• wherein said storage apparatus comprises:
• 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;
• and
• a cache memory for temporarily storing data sent and received from said host system;
• wherein said control method comprises:
• a first step, performed by a third control unit, of controlling reading and writing of data from and into said cache memory including writing said data sent from said host system in said cache memory at a prescribed opportunity;
• a second step, performed by a second control unit of controlling reading and writing of data from and into said disk device including writing said data sent from said third control unit in said disk device and, when a prescribed condition is satisfied, reading said data from said disk device;
• and
• a third step, performed by a first control unit of controlling reading and writing of data from and into said nonvolatile memory including writing said data read from said disk device in said nonvolatile memory.