The present invention proposes a storage system having a plurality of disk array apparatuses managed separately by different managers, that can considerably improve the reliability of data backup. The invention provides a storage system, in which a first disk array apparatus includes a storing unit for storing volume information, which is information about the configuration of the volume; an extracting unit for, when receiving an external backup instruction, extracting, according to the backup instruction, volume information, as backup volume information from the volume information stored in the storage unit, about a backup target volume; and a presenting unit for presenting the backup volume information extracted by the extracting unit to an external device, and the second disk array apparatus includes an allocating unit for allocating a corresponding second volume to the backup target volume by referring to the backup volume information presented by the presenting unit.