What is a metric stream?

A metric stream is an instance of one metric coming from one source.

For example, if you have a metric tracking CPU load across your servers and you have a source corresponding to a specific server instance, then the data arriving from that specific server is a single metric stream. The resolution of your metric is the resolution at which Librato stores your measurements.

If you are tracking CPU from a server cluster, then each server instance represents a metric stream for the CPU metric.