An information processing apparatus which implements a rebuild process for restoring a mirroring state even when each of a plurality of connected external storage devices is configured to input and output data to and from a host controller by accessing a storage area of the host controller. When the host controller has issued an instruction to carry out the rebuild process in which data in one of the external storage devices is copied to the other one, one of the external storage devices which is about to write data to the storage area of the host controller for the rebuild process is caused to write the data to the buffer provided in the bridge device, and the other one which is about to read data from the storage area of the host controller for the rebuild process is caused to read the data from the buffer.