A storage device includes a first storage unit, a second storage unit, a third storage unit, and a processor. The first storage unit is configured to store therein a part of a data group stored in a storage system. The second storage unit is configured to store therein partial hierarchical information which is a part of information on a hierarchical structure of the data group. The third storage unit is configured to store therein owner information including a data identifier in association with a device identifier. The data identifier identifies a specific data included in the data group. The specific data is related to the partial hierarchical information. The device identifier identifies a specific storage device. The specific device stores therein the specific data. The processor is configured to share management of the data group with other storage devices on basis of the partial hierarchical information and the owner information.