In a cluster setup, you can upgrade cluster nodes in any order. Use the following steps in this procedure to do a zero downtime upgrade in a cluster setup.
Procedure
Before performing an upgrade, enable the maintenance mode for the Avaya Hybrid Cloud Gateway node, for example, Node A.
The other nodes consider Node A as a failed node and trigger the failover procedure.
User registrations start moving gradually from Node A to the other nodes. Node A keeps servicing an agent until the node moves.
If an agent has a call on Node A, the user registration moves, but the call remains on Node A. The call remains to preserve call signaling. Avaya Hybrid Cloud Gateway cannot move the call state to another node.
During the movement of user registrations, view the UI counters that track registrations and active calls remaining on Node A.
For more information about viewing the counters for registrations and active calls, see Using maintenance commands.
After the UI counters drop to 0, upgrade Node A.
You can upgrade without impacting any agent functionality.
After Node A upgrades and starts, disable the maintenance mode.
For more information about disabling the maintenance mode, see Using maintenance commands. After disabling the maintenance mode, the failback procedure starts, moving the user registrations back to Node A.
Repeat this procedure for the other nodes, preferably one node at a time.
