Storage apparatus, computer system, and method

A storage apparatus, comprising:

• a controller coupled to a host computer;
• and
• a physical storage device coupled to the controller, wherein
• the controller includes:
• a processor configured to provide the host computer with a logical volume based on the physical storage device;
• a first memory coupled to the processor;
• a control device coupled to the host computer, the physical storage device, and the processor;
• and
• a second memory coupled to the control device,
• the control device writes into the second memory, based on a command from the host computer, address information that associates a logical address in the logical volume with a device address, which is an address in the physical storage device,
• the control device, upon receiving a command from the host computer,
• determines whether or not the command is a read command, and when determination is made that the command is a read command, identifies a first logical address designated by the read command and determines whether or not the first logical address is included in the address information,
• when the first logical address is included in the address information, specifies a first device address corresponding to the first logical address,
• reads read data stored in an area indicated by the first device address and transmits the read data to the host computer,
• when the first logical address is not included in the address information, transmits the command to the processor, and
• when determination is made that the command is a command other than a read command, transmits the command to the processor, and
• the processor executes a process designated by the command received from the control device.