Patent ID: 8127094

Claim:
A data processing system comprising: a first storage system configured with a virtual logical volume that comprises a dynamically expandable volume; an external storage system coupled to the first storage system; a host computer configured to input data to the virtual logical volume; and a management server coupled to the host computer, configured to manage the virtual logical volume, wherein the first storage system comprises: a first pool configured from a plurality of physical disks and comprising a plurality of segments each with a respective capacity, wherein the first storage system is configured to assign one or more of the plurality of segments of a storage region in the first pool as a current capacity to the virtual logical volume, in response to a request from the host computer to input data, wherein the management server is configured to perform a migration of data comprising: (A) confirming a connection status of the host computer and the virtual logical volume upon receiving a request from the host computer for migrating data corresponding to at least a part of the virtual logical volume, from the storage region in the first pool to an external storage region of the external storage system; (B) transmitting to the first storage system, as a reservation capacity, when the host computer and the virtual logical volume are coupled, a maximum capacity of the data held in the one or more segments of the storage region in the first pool requested by the host computer to be assigned to the virtual logical volume for the migration, and transmitting to the first storage system, as the reservation capacity, when the host computer and the virtual logical volume are not coupled, the current capacity of the one or more segments of the storage region in the first pool which are currently assigned to the virtual logical volume, wherein the first storage system is configured to reserve the external storage region of the external storage system, with a capacity based at least in part on the reservation capacity transmitted from the management server, and wherein the first storage system is configured to execute a migrating of at least a portion of the data corresponding to the virtual logical volume from the storage region in the first pool to the external storage region of the external storage system, after the reservation of the external storage region.