When a second storage device in a second site receives an update notification regarding a first element updated according to a write request from a first host, from a first storage device in a first site, for a second element specified on the basis of the update notification, the second storage device manages data of the first element corresponding to the second element as latest data. The first storage device provides a first volume capable of including a plurality of first elements. The second storage device provides a second volume capable of including a plurality of second elements corresponding to the plurality of first elements. When the second storage device receives a read request from a second host, the second storage device determines whether or not data of the first element corresponding to a read source second element (second element specified from the read request) is the latest data. When a determination result is true, the second storage device acquires the latest data from the first storage device and returns the latest data to the second host.