According to an aspect of an embodiment, an apparatus has a pair of first system boards, each of the first system boards including a processor and being adapted for sending duplicate requests, in parallel, respectively, a second system board including a processor and being adapted for sending requests, a first transfer device for transferring requests, having a first arbiter for selecting and outputting one of the duplicate requests sent from each of the first system boards, and a second arbiter for selecting and outputting one of the requests sent from the second system board and a second transfer device for transferring requests, having a third arbiter for selecting one of the duplicate requests sent from each of the first system boards and outputting the selected request in synchronization with the selected request outputted by the first arbiter, the second transfer device having a forth arbiter.