Patent ID: 7136855

Claim:
An exclusive control system for using a shared resource, comprising: a plurality of data access devices including a first and second data access device devices, and a shared storage device to which said plurality of data access devices can access, wherein said shared storage device stores a shared resource which said plurality of data access devices can use, and a first updatable information for said first data access device; said first access device comprises an access controller that accesses said shared resource if said shared resource is in unused status, that is, not being used by any of said data access devices, and said access controller does not access said shared resource if said shared resource is being used by any of said data access devices, and an information updater that updates said first updatable information; and said second data access device comprises a resource releaser that cancels said use status and releases said shared resource to said unused status if said first updatable information is not in a predetermined update result and said shared resource remains in use status being used by said first data access device, wherein when each data access device monitors any of said data access devices, said second data access device judges that said first data access device, which is the monitoring target of said second data access device, is not in operating status if said first updatable information is not updated, searches a subsequent data access device other than said first data access device in operating status which is not monitored by any of said data access devices, and monitors said subsequent data access device as a monitoring target.