A storage control apparatus is coupled to a central processing unit (CPU) and
a
storage unit to control input/output of data between the CPU and the storage unit.
The storage control apparatus has at least two processors coupled to the CPU and
the storage unit, a cashe memory (CM) unit for temporarily storing data of the
storage unit, a shared memory (SM) unit for storing information concerning control
of the CM unit and the storage unit, and a selector coupled to the at least two
processors, the CM unit and the SM unit through access paths to selectively apply
access requests from the at least two processors to the CM unit and the SM unit.