Patent ID: 7418533

Claim:
A data storage system comprising: a plurality of memory devices for storing data; a plurality of control modules which accesses the 5 memory devices according to access instructions from a mainframe unit and an open system unit; a plurality first channel adapter which performs interface control to the mainframe unit; and a switch unit connected to the plurality of first channel adapter and the plurality of control modules, and for selectively switching the connection between the plurality of first channel adapter and the plurality of control modules, wherein each said control module comprises: a cache memory which stores a portion of data stored in the memory devices; a second channel adaptor which performs interface control to the open system unit; a disk adapter for performing interface control to the plurality of memory devices; and a control unit which controls the cache memory in response to the accesses, and accesses the memory devices via the disk adapter, and wherein, said first channel adapter, in response to a write access from the mainframe unit, accesses in parallel both one said control module taking charge of the write data to be the target of the write access, and another said control module having mirror data of the control module in charge through said switch unit, so as to perform mirroring.