Abstract: Relay devices each include a port connected to a communication channel that is used to transfer and receive an access request to and from another relay device; a first virtual area section that is set as a virtual memory area that receives an access request; and a second virtual area section set as a virtual memory area for receiving an access request transferred from another relay device. The relay device sends, if a channel to a storage device is in operation, the access request that is sent to the first virtual area section and the access request that is sent to the second virtual area section, to the storage device via the channel. The relay device transfers, if the channel is not in operation, the access request sent to the first virtual area section, to another relay device via the communication channel connected to the port.

Abstract: A virtualizing switch includes a storage virtualizing section for making the host computer recognize storage areas prepared by combining storage areas of a physical storage devices as virtual storage devices, a data copying section for executing data copying between the virtual storage devices, a range locking section for dividing a storage area for storing data to be copied of a virtual storage device of a copy source into storage area parts having a previously set division size and inhibiting access to a divided storage area part, an instruction number counting section for counting the number of access instructions to the divided storage area part that is inhibited by the range locking section, and a divided capacity changing section for changing the division size based on the number of instructions counted by the instruction number counting section.

Abstract: A virtualization switch connected to a host computer and a plurality of physical storage devices includes a plurality of communication line connection terminals and storage virtualizing unit allowing the host computer to recognize a storage area generated by combining some or all of storage areas of the plurality of physical storage devices as a virtual storage device, a plurality of copy process unit copying data in the storage area, and control unit controlling a copy process operation by assigning copy sessions based on instructions from the host computer to the plurality of copy process unit. When the number of copy process units is larger than number of copy sessions, the control unit performs control to distribute part of a copy process in the one or copy process units that are currently performing the copy process to the one or more copy process units that are not performing the copy process.

Abstract: A disc array device for maintaining consistency of data. When write processing is interrupted and then restarted, new data may be stored in a nonvolatile memory and regeneration of parity may be impossible because data can not be read out normally from a disc device other than a disc device in which new data is to be written and a disk device for parity. In such a case, a special write executing unit overwrites the new data stored in the nonvolatile memory at a specified write position of the disk device in which new data is to be written.

Abstract: When write processing once interrupted is restarted, if new data is stored in a nonvolatile memory 34 and regeneration of parity is impossible because data can not be read out normally from a third disk device (for instance 32-2) other than a disk device (for instance 32-1) in which new data is to be written and a disk device (for instance 32-5) for parity, a data writing unit 113 in a special write executing unit 110 overwrites the new data stored in the nonvolatile memory 34 at a specified write position of an appropriate disk device (for instance 32-1).

Abstract: Each semiconductor memory module is divided into a plurality of access control units, and a service adapter copies the contents of the memory of the semiconductor memory module in which a memory error has occurred, to a spare semiconductor memory module one access control unit at a time. It is thus possible to evacuate the contents of the memory of the semiconductor memory module in which the memory error has occurred without stopping the semiconductor disk apparatus simply by adding the spare semiconductor disk apparatus. Since the copying operation is executed one access control unit at a time, a resource manager can conduct exclusive control also one access control unit at a time. A host apparatus therefore can access an access control unit portion which is not the object of copying even in the process of copying. In other words, the copying operation exerts no deleterious influence on the access of the host apparatus.