While disaster recovery is intended to ensure resiliency in an event of a failure, high availability is an additional mechanism to reduce the downtime in the event of a failure.
You can enable high availability for your database during provisioning, at an additional charge. When you provision high availability, we provision a standby of the same instance type. We continuously stream the transactions from the primary to the standby as they are committed. This provides an up-to-date copy that can be promoted to the primary in the event of a failure.
In order to provide high availability, the Crunchy Bridge control plane continuously monitors the health of both your primary and standby. If a health check fails against your primary, we run a deeper set of checks. If the primary does prove to be unhealthy, we initiate a failover to your standby.
During the failover, your connections will drop, so it is important you have reconnection logic within your database library (most ORMs and drivers support this out of the box). Your connections should automatically reconnect in a matter of seconds once the failover has completed. During a failover, your connection string stays the same and does not change.