System and method for creating logical pairs of storage devices in a multiprocessor environment

In a storage system coupled to a host apparatus a first storage control apparatus for controlling operations to write data into a storage device serving as a target specified by the host apparatus and read out data from the storage device, the first storage control apparatus comprising:

• a first processing unit connected to the host apparatus and configured to process a command received from the host apparatus;
• a cache memory configured to temporarily store data received from the host apparatus;
• a memory configured to store management information of the storage system;
• and
• a second processing unit configured to control an operation to transfer data stored in the cache memory to the storage device and connecting the storage system to a second storage control apparatus;
• and
• wherein when receiving the command, the first processing unit references the management information held in the first storage control apparatus to determine whether the command is a command issued to a logical device on a storage device controlled by the first storage control apparatus or a command issued to a logical device on a storage device controlled by the second storage control apparatus.

A storage system comprising:

• a first storage control apparatus configured to control operations to read out data from a storage device serving as a target specified by a host apparatus, the first storage control apparatus including:
• a first storage device configured to store data;
• a first processing unit connected to the host apparatus and configured to process a read command received from the host apparatus;
• and
• a second processing unit configured to read out the data from the first storage device and store the data in a cache memory in accordance with a processing result generated by the first processing unit;
• and
• wherein the storage system further includes a second storage control apparatus connected to the second processing unit, the second storage control apparatus including:
• a third processing unit configured to process a read command received from the second processing unit;
• a second storage device controlled by the second storage control apparatus;
• and
• a fourth processing unit configured to read out the data from the second storage device in accordance with a processing result generated by the third processing unit.

A control method adopted by a storage system having a host apparatus and a first storage control apparatus for controlling operations to write data into a storage device serving as a target specified by the host apparatus and read out data from the storage device, and in which the first storage control apparatus includes:

• a first processing unit connected to the host apparatus and configured to process a command received from the host apparatus;
• a first storage device configured to store data specified in a write command received from the host apparatus;
• a cache memory configured to temporarily store data specified in a write command received from the host apparatus or data read out from the first storage device in accordance with a read command received from the host apparatus;
• a memory configured to store management information of the storage system;
• and
• a second processing unit configured to control an operation to transfer data stored in the cache memory to the first storage device and connected to a second storage control apparatus to control a second storage device;
• the control method comprising:
• allowing the first processing unit to receive a data write or read command from the host apparatus;
• determining whether a command received from the host apparatus has been issued to a logical device on the first storage device or a logical device on the second storage device on the basis of the management information;
• and
• providing a control command to the second storage control apparatus if the step of determining indicates that a command received from the host apparatus has been issued to the logical device on the second storage device.