Abstract: 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.

Abstract: 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.

Abstract: A data storage device stores therein files as mirror source or mirror destination, and has ownership rights to files stored as mirror source. Having received a number of read/write requests to a file stored as mirror destination from a data processing device, the data storage device obtains an ownership right to the file, and updates ownership status of the file from mirror destination to mirror source. Thus, response time to the read/write requests to the file can be improved. After that, if the data processing device frequently requests another data storage device for access to the file, an ownership right to the file is transferred to the other data storage device, and accordingly, the ownership status of the file is updated.

Abstract: A data storage device stores therein files as mirror source or mirror destination, and has ownership rights to files stored as mirror source. Having received a number of read/write requests to a file stored as mirror destination from a data processing device, the data storage device obtains an ownership right to the file, and updates ownership status of the file from mirror destination to mirror source. Thus, response time to the read/write requests to the file can be improved. After that, if the data processing device frequently requests another data storage device for access to the file, an ownership right to the file is transferred to the other data storage device, and accordingly, the ownership status of the file is updated.