Virtualization controller and data transfer control method

A virtualization system for controlling data transfer between a host system and a plurality of storage devices, each of the storage devices having a disk controller and a plurality of disk drives related to at least one logical volume, the virtualization system comprising:

• a plurality of first ports coupled to the storage devices;
• a second port coupled to the host system;
• a processing circuit;
• and
• a memory configured to store mapping information, the mapping information indicating a relationship between first volume identification information, which is used by the host system to access a virtual volume in the virtualization system, 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 by the processing circuit for transferring data, which are sent from the host system and are related to the first volume identification information, to the first logical volume;
• wherein the virtualization system receives data, which are sent from the host system and are related to the first volume identification information, during a data transfer phase in which data stored in the first logical volume are transferred to a second logical volume of a second storage device of the storage devices, the data received during the data transfer phase are written to the second logical volume;
• and
• wherein, if the data transfer phase is completed, changed mapping information, instead of the mapping information, is used for transferring data, which are sent from the host system and are related to the first volume identification information, to the second logical volume, the changed mapping information indicating a relationship between the first volume identification information and third volume identification information for identifying the second logical volume and being stored in the memory.