MTTR, MTBF, and MTTA Explained
A practical reliability guide for engineering managers.
MTTR, MTBF, and MTTA Explained from Sandglass: practical guidance for using reliability metrics to improve detection and recovery without turning them into vanity numbers.
What this guide covers
This guide focuses on using reliability metrics to improve detection and recovery without turning them into vanity numbers. The goal is to make the operating decision clear before a stressful incident forces the team to improvise.
- MTTA measures how fast alerts are acknowledged.
- MTTR measures how fast service is restored.
- Outliers and repeat causes teach more than the average.
How Sandglass supports the practice
Track acknowledge time, recovery time, and recurring failure patterns from real incidents, then review outliers after recovery. Sandglass supports the continuous side of this work with checks, incidents, alert routing, and public status visibility.
- Back the practices here with HTTP, ping, TCP, content, SSL certificate, and heartbeat checks.
- Route incidents to email, Slack webhook channels, and generic webhooks so the right people respond fast.
- Use a public status page to keep customers informed while the team works the incident.
Common mistakes to avoid
Averages hide bad incidents. Look at the worst incidents and repeated causes before celebrating a lower monthly average.
Implementation checklist
Step 1: Start from customer impact
Decide which failures in this topic actually reach customers before adding any monitoring.
Step 2: Choose one signal per risk
Match each risk to a single HTTP, content, TCP, SSL certificate, or heartbeat check instead of stacking duplicates.
Step 3: Assign an owner and a channel
Give each alert one owner and one destination — email, a Slack webhook, or a generic webhook.
Step 4: Review after real incidents
Revisit intervals, thresholds, and ownership once a real incident shows what was missing.