Patent ID: 7877568

Claim:
A computer program stored on a computer readable storage medium and implemented in a virtualization system, the virtualization system is used to control data transfer between a host system and a plurality of storage devices, each of the storage devices comprising a disk controller and a plurality of disk drives related to at least one logical volume, the computer program comprising: code controlling storing of mapping information to be stored, the mapping information indicating a relationship between first volume identification information, which is used by the host system to access a virtual volume, and second volume identification information for identifying a first logical volume of a first storage device of the storage devices, the mapping information being used for transferring data, which is received from the host system and is related to the first volume identification information, to the first logical volume after converting the first volume identification to the second volume identification information; code controlling to transfer data, which are received from the host system during a data copy phase in which data stored in the first logical volume are copied to a second logical volume of a second storage device of the storage devices and is related to the first volume identification information, to the second logical volume; and code controlling a changed mapping information, instead of the mapping information, to be used, if the data copy phase is completed, for transferring data, which is received from the host system and is related to the first volume identification information, to the second logical volume after converting the first volume identification information to third volume identification information for identifying the second logical volume, the changed mapping information indicating a relationship between the first volume identification information and the third volume identification information.