How Many Metrics? A Guide to Estimating the Size of Your System

Published: 24 Sep 2019 by Tom Wilkie RSS

Our hosted metrics offering, Grafana Cloud, is billed based on usage; a common question we get is “How much will it cost to monitor N servers?” We charge $49/month for every 3,000 active series or 18,000 data points per minute (dpm), whichever is higher.

To help you understand what that translates to in terms of how much storage you need, here’s a rough guide to estimating the size of your system.

Graphite vs. Prometheus

The number of servers you can monitor for $49 with Grafana Cloud will depend on your choice of technology: Graphite or Prometheus.

Each 3,000 active series of Hosted Graphite is enough capacity to handle monitoring around 10 servers, assuming 300 series per server at up to 10-second resolution, when just looking at Linux-level performance metrics (CPU, Memory, disk and network).

Each 3,000 active series of Prometheus data is useful for ~4 servers; node_exporter can be set up to export ~700 active series per server, which at 15s scrape interval is 2,800 dpm.

Prometheus needs more series per server than Graphite, due to the use of more fine-grained metrics (per CPU, all CPU states etc.) than the default collectd setup. This, however, can be tuned by the user.

node_exporter vs. collectd

Collectd is the de-facto standard agent for Linux system monitoring and Graphite. Collectd is going to produce around 300 series and 1,800 dpm by default on a server that has 8 cores, 8 partitions, and 8 network interfaces.

node_exporter is the standard agent for Linux system monitoring in the Prometheus ecosystem. A good estimate is ~700 series for a similar server with node_exporter.