Abstract: A storage system forms a high availability pair for data duplication using a first volume of a first storage apparatus as a primary volume and a second volume of a second storage apparatus as a secondary volume. The first volume and a third volume of a third storage apparatus are used as a primary volume and a secondary volume, respectively, to form an asynchronous copy pair. The second volume and the third volume are used as a primary volume and a secondary volume, respectively, to form a standby pair. When a command to form the asynchronous copy pair is received, the storage system refuses to form the asynchronous copy pair when the standby pair is not formed yet.

Abstract: A storage system forms a high availability pair for data duplication using a first volume of a first storage apparatus as a primary volume and a second volume of a second storage apparatus as a secondary volume. The first volume and a third volume of a third storage apparatus are used as a primary volume and a secondary volume, respectively, to form an asynchronous copy pair. The second volume and the third volume are used as a primary volume and a secondary volume, respectively, to form a standby pair. When a command to form the asynchronous copy pair is received, the storage system refuses to form the asynchronous copy pair when the standby pair is not formed yet.

Abstract: A backup copy from a first data volume to a second data volume is executed according to either a synchronous mode, in which write data is copied from the first data volume to the second data volume in synchronous with a write request, or an asynchronous mode, in which journal data of a first storage apparatus is reflected on the second data volume in asynchronous with the write request. A second storage apparatus acquires secondary load information representing its own load status, and transmits the information to the first storage apparatus. The first storage apparatus acquires primary load information representing its own load status, determines switching between the modes based on the secondary load information, the primary load information and mode information, and transmits determination information representing determination results to the second storage apparatus.

Abstract: A backup copy from a first data volume to a second data volume is executed according to either a synchronous mode, in which write data is copied from the first data volume to the second data volume in synchronous with a write request, or an asynchronous mode, in which journal data of a first storage apparatus is reflected on the second data volume in asynchronous with the write request. A second storage apparatus acquires secondary load information representing its own load status, and transmits the information to the first storage apparatus. The first storage apparatus acquires primary load information representing its own load status, determines switching between the modes based on the secondary load information, the primary load information and mode information, and transmits determination information representing determination results to the second storage apparatus.