Abstract: A apparatus for controlling a first storage and a second storage, has a controller for receiving a write command and a read command sent out from a host and for sending out the write command and the read command to the first storage and the second storage, a determining unit for sending out a request corresponding to the write command to the first storage and the second storage, for receiving a first response corresponding to the request from the first storage and a second response corresponding to the request from the second storage, and for determining one of the storages on the basis of each of response times, a first writing unit for writing data into the determined storage, and a second writing unit for writing the data written in the determined storage into the other storage after writing the data into the determined storage by the first writing unit.

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 virtualization switch includes first communication line connection terminals which can be connected to a host computer, a physical storage apparatus or a plurality of physical storage apparatuses, and another virtualization switch, a second communication line connection terminal which can be connected to a single line concentrator or a plurality of line concentrators connected to a manager computer by a second communication line a storage virtualization unit, a first communication unit which can communicate with an other virtualization switch through a first communication line, second communication unit which can communicate with the other virtualization switch through an second communication line, second communication line monitor unit which test communication between the virtualization switch, and abnormal state coping unit which executes a closing process and causes the first communication unit to output a failover designation instruction.

Abstract: The storage virtualization switch is capable of correctly designating a virtual target when a host computer accesses the virtual target. A dummy virtual target, which corresponds to a virtual target, is put into an effective state after the virtual target is put into the ineffective state when the virtual target is put into the ineffective state, and the virtual target is put into an effective state after the dummy virtual target, which corresponds to the virtual target, is put into the ineffective state when the virtual target is put into the effective state.

Abstract: A virtualization switch includes first communication line connection terminals which can be connected to a host computer, a physical storage apparatus or a plurality of physical storage apparatuses, and another virtualization switch, a second communication line connection terminal which can be connected to a single line concentrator or a plurality of line concentrators connected to a manager computer by a second communication line a storage virtualization unit, a first communication unit which can communicate with an other virtualization switch through a first communication line, second communication unit which can communicate with the other virtualization switch through an second communication line, second communication line monitor unit which test communication between the virtualization switch, and abnormal state coping unit which executes a closing process and causes the first communication unit to output a failover designation instruction.

Abstract: The storage virtualization switch is capable of omitting to control (exclusion-control) a reserve condition on a physical storage unit without decreasing fault tolerance and reliability, so that overhead of access to the storage unit can be smaller. The storage virtualization switch comprises: a storage virtualization unit for constituting a virtual storage unit by using a storage area of the physical storage unit; a communication unit for communicating with another storage virtualization switch; and a zoning unit for making a host computer recognize an external virtual storage unit constituted in another storage virtualization switch connected by the communication unit, the zoning unit making the host computer access the external virtual storage unit via the communication unit when the host computer requests to access the virtual storage unit.

Abstract: The storage virtualization switch is capable of correctly designating a virtual target when a host computer accesses the virtual target. A dummy virtual target, which corresponds to a virtual target, is put into an effective state after the virtual target is put into the ineffective state when the virtual target is put into the ineffective state, and the virtual target is put into an effective state after the dummy virtual target, which corresponds to the virtual target, is put into the ineffective state when the virtual target is put into the effective state.

Abstract: A node according to the present invention, in a node which is to be instructed by a master node and communicates with an electronic device, performs an activation query notification to the master node. If it is determined that a response from the master node has not been made, the electronic device is allowed to communicate without an instruction from the master node, and it is also determined whether any other node is connected or not. If it is determined that some other new node is connected, the node instructs the other new node to communicate with the electronic device.

Abstract: The fiber channel switch is capable of protecting data even if communication for adjusting reserves of access rights, which is performed by communication means, is interrupted. The fiber channel switch comprises: a plurality of connection terminals connected to a host computer and a physical storage unit via fiber channels; a storage virtualization unit producing a virtual storage unit; a first communication unit for communicating with another fiber channel switch; an access adjusting unit for adjusting an access reserve between the fiber channel switches; a unit for setting a master-slave relation between the fiber channel switches; a block control unit for blocking access between the host computer and the physical storage unit via the fiber channel switch if the fiber channel switch is set as a slave when the communication between the fiber channel switches is interrupted.