We often have to tell customers about the need and impact of running many MMS agents. It would be nice to have the information in the FAQ.

We already cover how to achieve HA for the monitoring agents with http://mms.mongodb.com/help/faq/monitoring/#what-happens-if-a-monitoring-agent-becomes-unavailable-how-can-i-ensure-my-mongodbs-are-always-monitored, but let's add the following:

1. the fact that the additional non-active monitoring agents are at rest until they become the active agent
2. how to achieve HA for the backup agents by running more than one instance
3. the fact that the additional backup agents are also at rest if not active