Patent ID: 7133988

Claim:
A network storage virtualization method in a network storage system having a plurality of network storage devices, said method comprising: allowing a client connected via a network to access the network storage devices as one virtual network storage system; and permitting said client to access the network storage devices separately from said virtual network storage system, wherein a first network storage device includes a first disk interface (I/F) which is connected to an apparatus having a function of forming said network storage devices as one virtual network storage device, wherein a second network storage device includes a second disk I/F which is connected to said apparatus having a function of forming said network storage devices as one virtual network storage device and a host I/F which is connectable to an external device so as to permit said external device to access the network storage devices separately from said apparatus having a function of forming said network storage devices as one virtual network storage device, wherein said external device is permitted to access a secondary volume which is a copy of a primary volume and not permitted to access volumes other than said secondary volume, and further comprising the step of configuring access control of said secondary volume from outside of said apparatus having a function of forming said network storage devices as one virtual network storage device, wherein said configuring step comprises the steps of: creating a mirroring pair between said primary volume and said secondary volume at a certain point in time by taking a complete initial copy of said primary volume and storing said complete initial copy in said secondary volume; receiving in said second storage device a suspend request; placing the mirroring pair into a suspend status to permit setting of the access control according to user selection; if the user chooses a read only mode, setting said secondary volume to the read only mode for input/output (I/O) requests from said external device and re-synchronizing the mirroring pair; and if the user chooses a read/write mode, setting said secondary volume to the read/write mode for I/O requests from said external device and re-synchronizing the mirroring pair.