Service level objectives

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Our services may be small or incredibly deep and complex, but almost without fail these services can no longer be properly understood via the logs or stack traces we have depended on in the past. With this shift, we need not just new types of telemetry, but also new approaches for using that telemetry.

from Implementing Service Level Objectives
A Practical Guide to SLIs, SLOs & Error Budgets by Alex Hidalgo

What is a service level objective (SLO)?

A service level objective is the core concept of reliability engineering. It defines the target performance level you expect from your service—essentially, what you consider acceptable. SLOs help transform abstract reliability goals into measurable targets that align with user experience.

SLO core concepts

SLOs work in conjunction with two critical concepts:

Service level indicators (SLIs).
These are quantifiable metrics that measure specific aspects of your service's performance. They help you assess whether your service meets its SLO targets.
Error budgets.
This represents your allowance for failure—the acceptable number of errors or performance issues while still meeting your reliability targets. Error budgets help balance reliability with innovation.

SLO units in Nobl9

In Nobl9, an SLO unit corresponds to a unique error budget calculation based on:

Data ingested from your monitoring sources
Your defined reliability targets

This means every SLO requires:

A connection to a data source
At least one configured error budget

Each additional SLO target creates another error budget to track.

Implementing SLOs with Nobl9

Nobl9 streamlines the entire SLO lifecycle with comprehensive features:

Integrating data sources
Creating SLOs
Monitoring performance
Analyzing effectiveness
Managing issues

Practical application

With SLOs, you can monitor various service aspects:

API response times
Authentication success rates
Registration completions
Custom business metrics

For complex systems requiring end-to-end monitoring, Nobl9 provides the functionality to combine multiple SLOs into a composite view.

Best practices for effective SLOs

Having SLOs isn't enough—they must be meaningful and actionable. Your SLOs should:

Reflect real-world performance
Align with user experience
Surface actual issues
Provide trustworthy data

What's next?

Now that you understand what SLOs are and their role in measuring reliability, here's your path forward:

If you already have at least one project with a service in Nobl9, create your SLO
Start with connecting a data source and create SLO for one of your critical services. SLI Analyzer can help you identify the right metrics to monitor.
Master SLO management
Explore the essential operations for maintaining your SLOs with our SLO management guide, covering editing, copying, and moving SLOs as your needs evolve.
Set up alerting
Configure alert policies to notify you when your SLOs are at risk, ensuring you can respond to issues before they impact users.
Explore advanced patterns
Once comfortable with basic SLOs, explore specialized SLO guides for advanced topics like composite SLOs, different budgeting methods, and optimization techniques.
Scale your SLO practices:
- Set up data anomaly detection, assign responsible users to your service. Nobl9 Enterprise Edition users can benefit from SLO oversight features—with its reviews, data anomaly auto-detection capabilities, and the dedicated SLO oversight dashboard.
- Assemble your existing SLOs into a composite SLO to gain a unified view of your system's reliability and performance.

Effective SLO implementation is an iterative process. Start simple, learn from your data, and gradually refine your approach as your reliability practice matures.