This feature provides operational continuity of task scheduling. Talend Administration Center High Availability primarily ensures that there is always a scheduler (quartz) available to instantiate tasks as required. For more information, see section Talend High Availability.
The quartz cluster is in active - active configuration, so any Talend Administration Center node could potentially instantiate a job as per the schedule.
However, this should not be confused with High Availability of the Talend Administration Center web application, which must not be active - active, hence why a failover device is shown and not a load balancer. You must only use one Talend Administration Center node at any given time.
The primary use case for the failover device is if you use a third party scheduler to trigger jobs via the Talend Administration Center MetaServlet (API). If High Availability of the Talend Administration Center web application and / or MetaServlet is required, a network failover device (e.g. load balancers / proxies) can be used to achieve an active – passive configuration.