Patent ID: 6983349

Claim:
A method for controlling shared memories to permit I/O data exchange among storage controllers, at least one of said storage controllers being provided for each of a plurality of disk array devices, each of said storage controllers including at least one of said shared memories, each of said shared memories being capable of storing information about said disk array devices, said method comprising: on each said shared memory of each said storage controller, storing addresses of said shared memories of other ones of said storage controllers that could be a target for said I/O data exchange; receiving an I/O request from a host device with one storage controller A among said storage controllers; identifying, with said storage controller A that has received said I/O request, an address of a shared memory that manages a volume which is a target of said I/O request; if said identified address is an address of a shared memory of another storage controller B, issuing from said storage controller A to a switching device an instruction to establish a connection path between the shared memory of said storage controller A and the shared memory of said storage controller B, said switching device interconnecting said shared memories of said storage controllers; establishing a connection path between the share memory of said storage controller A and the shared memory of said storage controller B by said switching device according to said instructions; sending, by said storage controller A, said 1/0 request to the shared memory of said storage controller B via said switching device, upon installation of another storage controller, updating and synchronizing contents of each of said shared memories by registering in each of said shared memories an address of a shared memory of the installed storage controller, and upon deletion of another storage controller, updating and synchronizing contents of each of said shared memories by deleting from each of said shared memories an address of a shared memory of the deleted storage controller; and wherein said updating and synchronizing of the contents of said shared memories is performed at a predetermined timing, upon disk array device startup, or upon disk array device shutdown.