What should I use for time on irate/rate?

Grafana
1

Hey folks,

I’m new to Grafana and am trying to understand how time is used when generating irate/rate charts. We are using Prometheus as our primary datasource on a Kubernetes cluster using the stable/prometheus chart.

When I imported a dashboard from the marketplace, I noticed it had rate(query_field{app="selector"}[15s]). However, this resulted in “no data” on the graphs. If I changed 15s to 2m I started to get results.

From what I can see, Prometheus’ scrape defaults to 60 seconds. However, when I look at a graph with 2m set, I see data points every 15 seconds. As you can probably tell, I’m completely confused on what value to set for these queries.

Is there a guide somewhere, or someone have a minute to explain to me how to determine what this value should be?

Cheers,
Andrew

2

The value in square brackets must be at least 2x of the scrape interval. This is Prometheus’ limitation. This limitation has been removed in VictoriaMetrics - long-term remote storage for Prometheus.
As for the rate vs irate, prefer rate, since irate doesn’t capture spikes.