A-7
Theory of Controller Operation
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.
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
Controller 1
Channel 0
Controller 1
Channel 3
Controller 2
Channel 0
Controller 2
Channel 3
Both
controllers
online
Controller
1 LUNs
Passive
Controller
2 LUNs
Passive
Controller
1 Fails
Inactive
Inactive
Controller
2 LUNs
Controller
1 LUNs
Controller
2 Fails
Controller
1 LUNs
Controller
2 LUNs
Inactive
Inactive
Termination
Termination
Termination
Termination
Termination
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