Failover modes

The failover behavior outlined below corresponds to adapter instances with the Secondary failover role. Available failover modes may vary based on the adapter.

Hot failover

In hot failover mode, both the primary and secondary adapter are configured and are actively collecting data. The secondary instance is not transmitting data. Collected data is buffered into the failover-specific buffer folder until the adapter instance in the Primary role has finished sending data to the destination. Data from the Secondary adapter instance is not egressed to the data endpoint(s).

During a failover event, hot failover mode provides zero data loss.

Note: Because both primary and secondary instances are actively connected to the data source and collecting data, you must exercise caution in cases where the data selection item list is high as this could result in higher resource consumption on the data source and network throttling. AVEVA recommends using warm or cold failover mode configurations if you encounter issues.

Warm failover

Warm failover mode means that both the primary and secondary adapters are connected but only one is actively collecting data from its data sources. Since data is not being collected, data is not buffered nor egressed to the data endpoint(s).

When compared to cold failover mode, warm failover mode reduces data loss during a failover event; however, be advised that there is still some data loss.

Cold failover

Cold failover mode means that one adapter is actively collecting data from its data source while the secondary instance is configured but not connected to the data source. The adapter does not connect to nor collect data from the data source, and data is not egressed to the data endpoint(s).