Memory unit and circuit for shaping a communication signal

The invention relates to a storage unit with a channel control portion for receiving a data input / output request; a cache memory for storing data; a disk control section for performing an input / output processing of data according to the data input / output request; and a plurality of disk drives for storing data; wherein at least two of the disk drives with different communication speeds enter data in the disk control section and output therefrom. Further, the memory unit has a plurality of communication paths that are provided so as to connect at least one of the disk drives in such a way that a defined by the FC-AL fiber channel standards loop is formed, so that communication speeds for these different communication paths may be set differently.