Abstract: In a first management unit for a redundant array of independent disks (RAID management unit), a shared-class setting unit receives a shared-class setting command, for example, from a host computer. If the shared-class setting command includes information about the first RAID management unit and a second RAID management unit, a shared management-information creating unit creates shared management information, writes the created shared management information onto a first disk, notifies the second RAID management unit corresponding to a second disk about the shared management information, and gives an instruction to write the shared management information onto the second disk. The second RAID management unit then writes the notified shared management information onto the second disk.

Abstract: A method of transferring a virtual volume established on a real volume includes acquiring transfer source virtual volume information from a transfer source, acquiring transfer destination real volume information from a transfer destination, generating transfer destination virtual volume information from the transfer source virtual volume information by using the transfer destination real volume information, and establishing a virtual volume at the transfer destination based on the transfer destination virtual volume information.

Abstract: A mirroring controller includes a copy controller that selects one memory from among the plurality of memories as a copy source memory and copies data from the copy source memory to at least one copy target memory; and an I/O mirroring controller that copies, when a read request to the copy source memory is issued from an upper layer during copying by the copy controller, data from an area corresponding to the read request to the copy target memory, wherein, when processing corresponding to the read request to the copy source memory from the upper layer results in an error at the copy source memory during the copying by the copy controller, the copy controller controls the copy source memory so as to become unusable, and controls at least one copy target memory so as to act as a memory.

Abstract: In a RAID management apparatus, a disk determination unit accesses each of RAID devices, determines a copy source disk, and sets a pointer of the determined copy source disk into a disk management table stored in a storage unit. When an input-output (I/O) processing unit accesses a disk, if an I/O error occurs on the disk, as a result a copy source disk and a copy destination disk are switched; the I/O processing unit renews a pointer associated with the copy source disk in the disk management table stored in the storage unit, and a disk notification unit notifies that the copy source disk and the copy destination disk are switched.

Abstract: A method of transferring a virtual volume established on a real volume includes acquiring transfer source virtual volume information from a transfer source, acquiring transfer destination real volume information from a transfer destination, generating transfer destination virtual volume information from the transfer source virtual volume information by using the transfer destination real volume information, and establishing a virtual volume at the transfer destination based on the transfer destination virtual volume information.

Abstract: In a first management unit for a redundant array of independent disks (RAID management-unit), a shared-class setting unit receives a shared-class setting command, for example, from a host computer. If the shared-class setting command includes information about the first RAID management unit and a second RAID management unit, a shared management-information creating unit creates shared management information, writes the created shared management information onto a first disk, notifies the second RAID management unit corresponding to a second disk about the shared management information, and gives an instruction to write the shared management information onto the second disk. The second RAID management unit then writes the notified shared management information onto the second disk.