Patent ID: 8370682

Claim:
A virtual tape system comprising: a plurality of physical tape units; a virtual tape unit; a lower-level switch being coupled to the physical tape units; a plurality of integrated device processors (IDPs) being coupled to the lower-level switch, the IDPs being server computers to control the physical tape units by a first program to execute an action of the virtual tape unit; an intermediate-level switch being coupled to the IDPs; an upper-level switch being coupled to a user terminal equipment; a plurality of integrated channel processors (ICPs) being coupled to the intermediate-level switch and the upper-level switch, the ICPs being server computers to execute read/write processes of the virtual tape unit by a second program; a virtual library processor (VLP) being coupled to the intermediate-level switch, the VLP being a server computer to control the whole system by a third program; and a standby processor including a memory storing the first, second and third program so as to be capable of taking over and executing the actions of all of the IDPs, ICPs and VLP, and being coupled to all of the upper-level switch, the intermediate-level switch, and the lower-level switch, and; wherein the standby processor detects an abnormal state of each of the IDPs, ICPs and VLP, reads one of the first, second and third program corresponding to the abnormal processor from the memory when the abnormal state is detected, and takes over the operation of the detected abnormal processor by executing the read program.