File storage system and storage control method

A storage control method, which is carried out by a file storage system having three or more file storage apparatuses, the method comprising the step of, each time when a configuration of a migration path capable of including three or more file storage units arranged in a cascade form is changed,

• updating, using at least one computer coupled to each of the three or more file storage units, migration path management information that indicates the configuration of the migration path, to information that indicates the changed configuration of the migration path,
• adding, using the at least one computer, the information that indicates the changed configuration of the migration path to path history information that indicates a change history of the configuration of the migration path;
• storing, using each of the file storage apparatuses independently, storage unit management information and file management information,
• wherein
• the storage unit management information is information that includes migration destination information on a migration destination file storage unit corresponding to the file storage unit associated with the file storage apparatus having the storage unit management information,
• the migration destination information included in the storage unit management information is information that is included in the storage unit management information based on the migration path management information,
• the file management information is information on a file that is stored in the file storage apparatus having the file management information and includes the migration destination information, which is information on the migration destination file storage unit to which the file is migrated, and migration source information, which is information on a migration source file storage unit from which the file is migrated;
• storing, using each of the file storage apparatuses independently, migration source history information, which indicates a change history of the migration source information that is included in the file management information of the each file storage apparatus, and migration destination history information, which indicates a change history of the migration destination information that is included in the file management information of the each file storage apparatus;
• using each file storage apparatus independently to:
• migrate a file within the file storage unit associated with the each file storage apparatus, to the migration destination file storage unit corresponding to the file storage unit, the migration destination file storage unit being specified from the storage unit management information, and then convert the file into a stub, and
• include information on the migration destination file storage unit in the file management information as migration destination information corresponding to the stub, and then add the information on the migration destination file storage unit to the migration destination history information;
• wherein
• changing the configuration of the migration path involves path change, which is to delete an intermediate file storage unit of the migration path from the migration path,
• each time when the configuration of the migration path is changed, using the at least one computer to delete information on the file storage unit to be deleted from the migration path management information, and to add, to the path history information, information that indicates the configuration of the migration path obtained after the path change,
• using a third file storage apparatus, which is associated with a third file storage unit that is a migration source file storage unit corresponding to the file storage unit to be deleted, to acquire information on a link of a stub of the third file storage apparatus from the file storage apparatus associated with the file storage unit to be deleted,
• using the at least one computer to transmit, to the third file storage apparatus, a first path change instruction that includes information on a fourth file storage unit, which is a migration destination file storage unit corresponding to the file storage unit to be deleted, and to transmit, to a fourth file storage apparatus, a second path change instruction that includes information on the third file storage unit, which is the migration source file storage unit corresponding to the file storage unit to be deleted,
• using the third file storage apparatus to:
• receive the first path deletion instruction, and
• change the migration destination information corresponding to the stub in the file management information, to the information on the fourth file storage unit that is included in the first path deletion instruction, and add the information on the fourth file storage unit to the migration destination history information;
• and
• using the fourth file storage apparatus to:
• receive the second path deletion instruction, and
• change the migration source information corresponding to the file in the file management information, to the information on the third file storage unit that is included in the second path deletion instruction, and add the information on the third file storage unit to the migration source history information.

A management computer, which is coupled to three or more file storage apparatuses, the management computer comprising:

• a communication interface device coupled to each of the three or more file storage apparatuses;
• a storage resource;
• and
• a controller that is coupled to the communication interface device and the storage resource,
• wherein
• the storage resource is configured to store migration path management information, which indicates a configuration of a migration path capable of including three or more file storage units arranged in a cascade form, and path history information, which indicates a change history of the configuration of the migration path, and
• each time when the configuration of the migration path is changed, the controller is configured to update the migration path management information to information indicating the changed configuration of the migration path, and to add the information indicating the changed configuration of the migration path, to the path history information;
• wherein
• each of the file storage apparatuses is independently configured to store storage unit management information and file management information,
• the storage unit management information is information that includes migration destination information on a migration destination file storage unit corresponding to the file storage unit associated with the file storage apparatus having the storage unit management information,
• the migration destination information included in the storage unit management information is information that is included in the storage unit management information based on the migration path management information,
• the file management information is information on a file that is stored in the file storage apparatus having the file management information and includes the migration destination information, which is information on the migration destination file storage unit to which the file is migrated, and migration source information, which is information on a migration source file storage unit from which the file is migrated,
• each of the file storage apparatuses further is independently configured to store migration source history information, which indicates a change history of the migration source information that is included in the file management information of the each file storage apparatus, and migration destination history information, which indicates a change history of the migration destination information that is included in the file management information of the each file storage apparatus, and
• the each file storage apparatus is independently configured to:
• migrate a file within the file storage unit associated with the each file storage apparatus, to the migration destination file storage unit corresponding to the file storage unit, the migration destination file storage unit being specified from the storage unit management information, and then convert the file into a stub, and
• include information on the migration destination file storage unit in the file management information as migration destination information corresponding to the stub, and then add the information on the migration destination file storage unit to the migration destination history information;
• wherein
• changing the configuration of the migration path involves path change, which is to delete an intermediate file storage unit of the migration path from the migration path,
• each time when the configuration of the migration path is changed, the management computer is configured to delete information on the file storage unit to be deleted from the migration path management information, and to add, to the path history information, information that indicates the configuration of the migration path obtained after the path change,
• (X) a third file storage apparatus, which is associated with a third file storage unit that is a migration source file storage unit corresponding to the file storage unit to be deleted, is configured to acquire information on a link of a stub of the third file storage apparatus from the file storage apparatus associated with the file storage unit to be deleted,
• the management computer is configured to transmit, to the third file storage apparatus, a first path change instruction that includes information on a fourth file storage unit, which is a migration destination file storage unit corresponding to the file storage unit to be deleted, and to transmit, to a fourth file storage apparatus, a second path change instruction that includes information on the third file storage unit, which is the migration source file storage unit corresponding to the file storage unit to be deleted,
• the third file storage apparatus is configured to:
• receive the first path deletion instruction, and
• change the migration destination information corresponding to the stub in the file management information, to the information on the fourth file storage unit that is included in the first path deletion instruction, and add the information on the fourth file storage unit to the migration destination history information;
• and
• the fourth file storage apparatus is configured to:
• receive the second path deletion instruction, and
• change the migration source information corresponding to the file in the file management information, to the information on the third file storage unit that is included in the second path deletion instruction, and add the information on the third file storage unit to the migration source history information.