Patent ID: 7519854

Claim:
A serial SCSI (SAS) storage drive system, comprising a first SAS drive enclosure comprising: a first plurality of storage drives; first and second interface cards; a first SAS expander programmable to couple the first interface card with at least a first of the first plurality of storage drives through a first port; a second SAS expander programmable to couple the second interface card with at least a second of the plurality of storage drives through a second port; a first crossover port selectively interconnecting the first interface card with the second interface card; the first interface card comprising a first demultiplexer having a first data terminal coupled to the first storage controller, a second data terminal coupled to the first expander and a third data terminal coupled to the first crossover port; the second interface card comprising a second demultiplexer having a first data terminal coupled to the second storage controller, a second data terminal coupled to the first expander and a third data terminal coupled to the first crossover port; and logic associated with each interface card programmed to detect when a failure has occurred in the first or second storage controller; the logic associated with the first interface card being programmed to: direct the first demultiplexer to interconnect the first and second data terminals of the first interface card in the absence of a failure in the first storage controller; and direct the first demultiplexer to interconnect the first and third data terminals of the first interface card when a failure in the first storage controller is detected; and the logic associated with the second interface card being programmed to: direct the second demultiplexer to interconnect the first and second data terminals of the second interface card in the absence of a failure in the second storage controller; and direct the second demultiplexer to interconnect the first and third data terminals of the second interface card when a failure in the second storage controller is detected; whereby: if the failure occurred in the first storage controller, the second storage controller is coupled to the first interface card, whereby access to the at least first storage drive is maintained; and if the failure occurred in the second storage controller, the first storage controller is coupled to the second interface card, whereby access to the at least second storage drive is maintained.