A data processing system, comprising: data processing apparatuses for processing data; a data transfer apparatus that includes first and second control units (21, 22) to control communication between the data processing apparatuses and includes a processing apparatus information sending unit for sending, when one of the first and second control units (21, 22) fails, a piece of processing apparatus information corresponding to the data processing apparatus under control of the failed control unit from among pieces of processing apparatus information uniquely attached respectively to the data processing apparatuses to a system control apparatus; and the system control apparatus that includes a partition determining unit for determining each partition, that logically divides the system, to which the data processing apparatus corresponding to the piece of processing apparatus information sent by the data transfer apparatus belongs, and a stop command sending unit for sending a stop command to stop each of the data processing apparatuses belonging to each determined partition, affected by the failed control unit (21, 22), wherein the processing apparatus information sending unit is adapted to: receive a piece of processing apparatus information from a failure checker of a failed control unit (21, 22), the piece of processing apparatus information containing first applicability information indicating whether the piece of processing apparatus information is valid and the ID of the failed control unit (21, 22); receive an enable signal from which it is determined which of the data processing apparatuses are under the control of the failed control unit (21, 22); check the enable signal and the first applicability information in the received piece of processing apparatus information to determine whether the piece of processing apparatus information is valid; send the ID of the failed control unit (21, 22), and the ID of the data processing apparatus containing second applicability information indicating whether the ID of the data processing apparatus is valid, to the system control apparatus; and send the piece of processing apparatus information to a register update unit adapted to update a partition information storage unit of the system control apparatus in accordance with the piece of processing apparatus information. data processing apparatuses for processing data; a data transfer apparatus that includes first and second control units (21, 22) to control communication between the data processing apparatuses and includes a processing apparatus information sending unit for sending, when one of the first and second control units (21, 22) fails, a piece of processing apparatus information corresponding to the data processing apparatus under control of the failed control unit from among pieces of processing apparatus information uniquely attached respectively to the data processing apparatuses to a system control apparatus; and the system control apparatus that includes a partition determining unit for determining each partition, that logically divides the system, to which the data processing apparatus corresponding to the piece of processing apparatus information sent by the data transfer apparatus belongs, and a stop command sending unit for sending a stop command to stop each of the data processing apparatuses belonging to each determined partition, affected by the failed control unit (21, 22), wherein receive a piece of processing apparatus information from a failure checker of a failed control unit (21, 22), the piece of processing apparatus information containing first applicability information indicating whether the piece of processing apparatus information is valid and the ID of the failed control unit (21, 22); receive an enable signal from which it is determined which of the data processing apparatuses are under the control of the failed control unit (21, 22); check the enable signal and the first applicability information in the received piece of processing apparatus information to determine whether the piece of processing apparatus information is valid; send the ID of the failed control unit (21, 22), and the ID of the data processing apparatus containing second applicability information indicating whether the ID of the data processing apparatus is valid, to the system control apparatus; and send the piece of processing apparatus information to a register update unit adapted to update a partition information storage unit of the system control apparatus in accordance with the piece of processing apparatus information.