Visual Assistance for Optimum Cabling
Original Publication Date: 2002-Jan-26
Included in the Prior Art Database: 2003-Jun-20
Disclosed is a system for the Fibre Channel Arbitration Loop (FC-AL) storage enclosure to be connected with other enclosures in dual-loop configuration. The enclosures give the visual assistance by controlling indicators for specifying the external ports to be connected. A storage subsystem is made of an enclosure which contains a number of harddisk drives, or made of multiple enclosures connected together when the storage capacity needs to be expanded. For the high availability of storage subsystem, such interconnections between enclosures need to have the redundant data paths to tolerate the failure, and the storage subsystem with FC-AL interface is typically used in dual-loop configuration for that purpose. The figure 1 illustrates how FC-AL enclosures are cascaded in dual-loop configuration. In this figure, the cabling of loop A and loop B is not symmetric. For example, the data from the primary enclosure to the expansion enclosure #1 goes through the expansion enclosure #2 for loop A and it goes directly for loop B. In the event when an expansion enclosure cannot serve as the intermediate for both loops, this cabling method retains the data path between the other enclosures by either loop. Another factor of planning the enclosure interconnections is the order of drive addresses in FC-AL loops to minimize the protocol overhead. This requires the significant knowledge of storage subsystem's internal architecture and FC-AL protocol.