There is provision to monitor Business Service into two aspects. One is “Availability” and the other one is “Health”. Availability can be modeled to monitor whether the service is available or not for end user and health can be monitored by assigning the weightage for individual components including redundant components (they also configured individually for monitoring). If any of the redundant component is down then health will be down by weightage provided to that component but the availability of the service is still 100% as its redundant component and user will not get impacted. But thresholds can be set for the health of the service and since its down by its weightage and if it breaches the threshold then alerts will be generated.
Please refer another article published in community - What are Availability and Health of Business Service?