Telemetry traffic is a small fraction of the the total traffic running through a region, partially due to the use of the Smile data format (binary JSON) for delivering metrics from the client to the Atlas backend.
When you give developers tools for creating and aggregating highly dimensional metrics, they tend to create lots of metrics so that they can answer interesting business questions about the use of their applications. We have some developers who have written code that produces up to 150,000 metrics per instance and the vast majority of these metrics are application-level. We typically see 3-5% of the metrics delivered from an instance are system-level performance metrics.
And this, of course, doesn't account for cases where a minor developer error results in code that, say, creates a new metric for every source IP address from which we see a request. Dynamic metric names FTW.
When you give developers tools for creating and aggregating highly dimensional metrics, they tend to create lots of metrics so that they can answer interesting business questions about the use of their applications. We have some developers who have written code that produces up to 150,000 metrics per instance and the vast majority of these metrics are application-level. We typically see 3-5% of the metrics delivered from an instance are system-level performance metrics.