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RunBook Academy

ObservabilityXXVI · Dashboard DesignDashboardDesign

Units and Thresholds

Foundation⏱ ~16 minbash

What you'll learn

  • Explain units and thresholds in production terms
  • Configure and operate units and thresholds in a production observability stack
  • Recognise and diagnose the most common failure modes
  • Apply the discipline to a real Prometheus / Grafana / Loki / Tempo environment

Prerequisites

Verified against Prometheus 2.55.x · Alertmanager 0.28.x · node_exporter 1.8.x · blackbox_exporter 0.26.x · Grafana 11.x · Loki 3.x · Tempo current · OpenTelemetry Collector 0.110.x · Grafana Alloy current · Docker Engine 28.x · Ubuntu 24.04 LTS · Debian 12 (Bookworm) · RHEL / Rocky / AlmaLinux 9.x · 2026-08-13

Not yet marked complete on this device.

Units (bytes, seconds, reqps) and thresholds (80%, 95%) must be consistent across dashboards.

A team that documents the conventions speeds up understanding.

What it is

A precise definition of units and thresholds, scoped to production operations.

Why a sysadmin cares

Production framing. The operational pain this concept addresses, or the incident class it prevents.

How it works

The mental model.

How to configure it

# Configuration snippet illustrating the lesson topic
example_setting: value

How to validate it

promtool check config /etc/prometheus/prometheus.yml

How it can fail

The high-frequency failure modes:

  1. Silent misconfiguration.
  2. Crash on load.
  3. Performance regression.
  4. Permissions failure.
  5. Schema / version drift.

How to troubleshoot it

The diagnostic order:

  1. Was it working before?
  2. What does the service’s view say?
  3. What does the platform’s view say?
  4. Form hypothesis, find evidence, test, validate.

Security implications

Units and Thresholds has security implications wherever the relevant component exposes an HTTP endpoint, an authentication layer, or a credential.

Performance implications

Performance implications come from cardinality, scrape / push interval, rule size, retention, and query cost.

Production guidance

  • Validate before applying.
  • Test changes in a non-production environment.
  • Document operational defaults in the team’s instrumentation guide.

Verification

You should now be able to answer:

  • What is units and thresholds in production terms?
  • Why does a sysadmin care about it?
  • How does it fail and how do you diagnose the failure?

Quiz

Knowledge check · 8 questions

  1. Q1. What is the primary purpose of units and thresholds?

  2. Q2. Which failure mode of units and thresholds is most operationally costly?

  3. Q3. Production verification should run on production hosts.

  4. Q4. First response when units and thresholds misbehaves?

  5. Q5. Name one signal that confirms units and thresholds is healthy.

  6. Q6. Which of these are validation steps?

  7. Q7. Right discipline when changing in production?

  8. Q8. Telemetry usefulness requires:

Passing score: 75%. Answers are checked in this browser.