Data processing system

A data processing system, which maintains a duplication of a data between sites each having a host computer and a storage apparatus, comprising:

• a primary site having a primary host computer and a primary storage apparatus, connected to the primary host computer, including a control section and a storage unit, wherein primary user data is stored in a storage area;
• a secondary site having a secondary host computer and a secondary storage apparatus, connected to the secondary host computer, including a control section and a storage unit, wherein a duplicate of the primary user data is stored in a storage area as secondary user data;
• and
• an intermediate processing section, which is connected to the primary storage apparatus through a communication link and is connected to the secondary host computer;
• wherein the control section of the primary storage apparatus accumulates update data in the storage area within the primary storage apparatus together with its management information when an update of the primary user data is performed based on a command from the primary host computer,
• wherein, being asynchronous with the update of the user data, the control section of the primary storage apparatus and the intermediate processing section perform remote-copy of or move and accumulate of the update data and its management information in the storage area of the intermediate processing section through the communication link,
• wherein the secondary host computer and the intermediate processing section commands the control section of the secondary storage apparatus to perform a processing to transfer the update data and its management information accumulated in the intermediate processing section to the secondary host computer and to reflect the transferred data on the secondary user data for updating,
• wherein the control section of the primary storage apparatus makes the management information for managing an update data when the update of the primary user data is performed based on a command from the primary host computer,
• wherein the management information is made to include therein an update serial number or an update time as an identifier of an update sequence of the primary user data, an update address of the primary user data, and a storage address of the update data, and
• wherein the secondary host computer performs the processing of updating and reflecting the update data on the secondary user data based on the management information.