Patent ID: 7574555

Claim:
A data storage system having an interface for coupling a host computer/server to a bank of disk drives, such interface having a pair of redundant packet switching networks, each one being coupled to front end controllers, back end controllers and a cache memory, such cache memory, comprising: a pair of bi-directional ports, each one being connected to a corresponding one of the pair of packet switching networks, each one of the ports providing address and read/write control signals to the memory system; a plurality of sets of memory modules; a plurality of memory controllers, each one of the memory controllers being coupled to a corresponding one of the plurality of sets of memory modules; wherein each one of the memory controllers includes an arbiter coupled to the corresponding one of the plurality of sets of memory modules, such arbiter being coupled to the pair of bi-directional ports to determine which one of the pair of bi-directional ports is to have access to the one of the sets of memory modules coupled to such one of the arbiters; and wherein the memory controllers are interconnected in a daisy chain arrangement to the ports, a first one of the memory controllers in the daisy chain being coupled to a first one of the pair of ports and a last one of the memory controllers in the daisy chain being coupled to a second one of the pair of ports; and wherein a signal path for the address and read/write control signals from the first one of the pair of ports through the controllers is in a direction opposite to a signal path for the address and read/write control signals from the second one of the pair of ports through the controllers.