D-Link DSN-500 Software User's Manual page 94

Dual controller systems provide redundancy for High Availability. Under normal conditions,
both controllers in the Primary Array function as a "Bound" pair. They operate together
and all system activity on the primary controller is mirrored to the redundant controller. In
the event of a controller failure, the system will automatically transfer all system
configuration information (including Management Port and Data Port IP addresses) and any
cached data to the redundant controller, without any interruption to the host servers.
When a controller failure occurs, the remaining controller becomes a "Survivor", and the
failed controller is allowed to restart and REBIND. If the failed controller is unable to
REBIND due to a hardware failure, it is held in a non-functional state. After repairing or
replacing the failed controller, the system will automatically return to a BOUND state.
If the controllers are unable to bind during the system startup process, the system state will
appear as "Unable to Bind", and the reason for the failure will appear in the Main Display.
At a minimum, both controllers must be equipped with the same number of iSCSI data ports
and the same amount of Buffer Memory, and must be running the same version of software.
Figure 6-3. System Administration View – Controller Selected (Dual Controller Systems)
Refer to Section 6.2 for a description of the Details Tabs. The System Administration View
only displays a System Actions panel, which includes a "Force System Failover" selection
for testing the automated controller failover.
84 Chapter 6 System Administration