Adaptec 412R User Guide - Page 109

Theory of Controller Operation Termination Termination Termination Termination Termination Figure A-5 Stand-Alone Dual-Port with Dual Host (Quad Cabling) Active-Active Mode In the active-active mode, the two RAID controllers cooperate to provide redundancy. If one controller fails, the remaining controller will take over the failed controller's functionality. Each controller has two SCSI host ports, they are labeled in the diagrams as "CH 0" and "CH 3." In the active-active single-port mode, one host port is normally active, and the other is normally passive. In a failed over condition, the passive port of the surviving controller becomes active and assumes the identity of the failed controller. This failover process occurs without user intervention. Table A-3 lists the presentation of LUNs in active-active single-port mode. Table A-3 Presentation of LUNs in Active-Active Single-Port Mode Controller Status Both controllers online Controller 1 Fails Controller 2 Fails Controller 1 Channel 0 Controller 1 LUNs Inactive Controller 1 LUNs Controller 1 Channel 3 Passive Inactive Controller 2 LUNs Controller 2 Channel 0 Controller 2 LUNs Controller 2 LUNs Inactive Controller 2 Channel 3 Passive Controller 1 LUNs Inactive A-7