Upon receiving an input of data, an input unit transmits a time notification to another input unit and transmits a data notification including the input clock time to a storage unit. Upon receiving a time notification from another input unit, the input unit transmits an empty notification including the input clock time to the storage unit to indicate there is no input before the input clock time. Upon receiving the data notification from an input unit having received the input of data and receiving the notification from the other input unit, the storage unit broadcasts the data in order, assuming that consensus of the plurality of storage units is confirmed. When adding an input unit to a computer system, a control device causes the storage unit to start confirming the consensus including the joining input unit after a window interval has elapsed after the joining input unit starts operation.