Patent ID: 7636818
Filing Date: 2009-12-22
Classification: G06F,H04L

Abstract:
1. A storage virtualization system comprising: a plurality of storage virtualization apparatuses coupled to an upper order apparatus and a storage subsystem; and a shared storage area shared by said plurality of storage virtualization apparatuses, said shared storage area storing device configuration information expressing a logical device configuration in said plurality of storage virtualization apparatuses, wherein said logical device configuration is a relationship between one or more external storage devices serving as a storage device of said storage subsystem and one or more internal storage devices which serves as logical storage area in said plurality of storage virtualization apparatuses, wherein each of said plurality of storage virtualization apparatuses comprises: a configuration information storage area for storing said device configuration information; and a controller for receiving a first access command specifying an internal storage device from said upper order apparatus, generating a second access command for accessing an external storage device associated with said specified internal storage device based on said device configuration information stored in said configuration information storage area, and transmitting said second access command to said storage subsystem, wherein said controller of a newly coupled storage virtualization apparatus from among said plurality of storage virtualization apparatuses, which is newly coupled to said upper order apparatus and said storage subsystem, reads said device configuration information from said shared storage area and writes said read device configuration information into said configuration information storage area, wherein a plurality of internal storage devices in said plurality of storage virtualization apparatuses are associated with a single external storage device provided by said storage subsystem, wherein said controller of one of said plurality of storage virtualization apparatuses writes modification desire information, which is information expressing a desire to modify said device configuration information, in said shared storage area, wherein when said external storage device mapped in said device configuration information is in use, another controller in another of said plurality of storage virtualization apparatuses writes modification denial information denying modification into said shared storage area, and when said external storage device mapped in said device configuration information is not in use, said other controller in said other storage virtualization apparatus writes modification permission information permitting modification into said shared storage area, and wherein when said modification denial information is written in said shared storage area, said controller does not modify said device configuration information, and when said modification permission information is written in said shared storage area and said modification denial information is not written in said shared storage area, said controller modifies said device configuration information.