Patent ID: 8127093

Claim:
A computer system, comprising: a first storage system; a first server computer which is coupled to the first storage system and which manages the first storage system; wherein the first storage system comprises storage media, which have a plurality of physical storage areas, and a controller, which defines a plurality of logical volumes using the storage media to control data write to the storage media and data read out of the storage media, wherein the first storage system makes at least one of the plurality of logical volumes recognizable to the first server computer, wherein each of the plurality of logical volumes has a storage area space including a plurality of address ranges, wherein, upon reception of a request to write data in one of the plurality of address ranges, the first storage system allocates at least one of the plurality of physical storage areas, that is not allocated to any of the plurality of address ranges, to the one of the plurality of address ranges where the data is requested to be written, and stores the data requested to be written in the allocated physical storage area, wherein the plurality of logical volumes include a first logical volume and a second logical volume, wherein the plurality of address ranges in the second logical volume are not allocated to the plurality of physical storage areas, wherein the first server computer comprises a first interface, which communicates with the first storage system, a first processor, which is coupled to the first interface, and a first memory, which is coupled to the first processor, wherein the first server computer holds information identifying data stored in the first logical volume, wherein the first server computer executes a migration processing to make every piece of data stored in the first logical volume migrate to the second logical volume, wherein, upon reception of the request to make the data migrate, the first server computer sends to the first storage system a request to read every piece of data stored in the plurality of address ranges of the first logical volume and a request to write the every piece of data in the plurality of address ranges of the second logical volume, wherein, after the every piece of data has been written in the plurality of address ranges of the second logical volume, the first server computer sends a request to the first storage system to delete the first logical volume, and wherein, upon reception of the request to delete the first logical volume, the first storage system deletes the first logical volume.