User Manual

Advanced Functions
5-32
Normally, the heartbeat LED on each controller board is flashing
periodically and the system keeps syncing state messages shown on the
GUI to identify the controller is alive. When a heartbeat LED does not flash
anymore, or the state message cannot be synced, the controller will be
regarded as failed.
Controller Failback
If a system is in the controller failover mode, the survival controller will take
over the failed controller’s job and process its own job. When a healthy
replacement controller is installed, the system will proceed the failback
process. The survival controller will return the failed controller’s job and
sync all states and configuration to the failback controller.
When the redundant mode is established, the heartbeat LED of the
failback controller flashes. Never remove or power down (through the
GUI) the survival controller before the failback controller heartbeat LED
starts flashing.
• GUI Notification
When one of the controller is failover, the following notification message
will be displayed and provide the link to the backup controller. Click ‘Go
to peer controller’s GUI’ to view or configure settings.
When a controller is failback, a pop-up dialog box appears to notify users
that the system is doing failback (GUI screen is polling every 15 seconds).
Users can click the OK button when the failback process is finished.
Note
When the heartbeat LED of both controllers are flashing, users are
allowed to hot remove any one controller.
Note
1. Only the tasks belong to the preferred controller will be returned
to the failback controller. If you have changed the preferred
controller for tasks to the survival controller, the survival controller
then takes the ownership of those tasks. For more information
about preferred controller, see Owner controller and preferred
controller on page 5-20.
2. The replacement must be exactly the same controller as the
surviving one, as mentioned previously.
Figure 5-13 Controller failover and the page redirection message