The method of production storage system and storage system

In a storage system 1, a storage apparatus A having a first pool 1430 including segments as unit storage areas and a storage apparatus B having a second pool 1430 having the same configuration are communicably connected to each other. In the storage system, an external volume identifier is associated with a logical volume 1420 included in the first pool 1430, the external volume identifier being used by a controller 1500 in the storage apparatus B to identify and manage the logical volume 1420 as an external volume 1425 that is a virtual volume in the storage apparatus B. Moreover, a volume identifier 5110 of the logical volume 1420 included in the first pool 1430 is rewritten into the external volume identifier in order to enable the storage apparatus B to utilize the logical volume 1420 created from the first pool 1430.