firmware unit 203 lifts the forbidden access to read data from the storage circuit group b 115 step h then the firmware unit 203 forbids the storage circuit group a 114 the side on which the interleave setting has not been changed from being accessed in a direction of reading step i the firmware unit 203 shifts the storage circuit group a 114 for which reading access has been forbidden from the 2 way interleave setting into the 3 way interleave setting step j the firmware unit 203 copies data stored in the storage circuit group b 115 into the storage circuit group a 114 step k upon completing the process for copying the data in the storage circuit group b 115 into the storage circuit group a 114 the firmware unit 203 lifts the forbidden access to read data from the storage circuit group a 114 step l the firmware unit 203 restarts a check on agreement of data read from the memories 104 107 205 and 206 rendered duplex to the memory controller 103 step m the firmware unit 203 notifies the driver 202 that the process for changing the interleave setting is finished and the driver 202 requests the os 201 to restart a transaction including memory access step n fig4 is a flowchart of an interleave setting in the server 100 of the embodiment a change in the interleave setting done by the server 100 will be explained in more detail by the use of the flowchart illustrated in fig4 if the memories 205 and 206 are added to the storage circuit group a 114 and the storage circuit group b 115 respectively the firmware unit 203 and the memory controller 103 recognizes.