Unified Service Intelligence & SLO Management

• SLI (Service Level Indicator) is a metric that quantifies service performance, such as latency, error rate, or availability
• SLO (Service Level Objective) is a target value or range for an SLI, representing internal goals for service quality
• SLA (Service Level Agreement) is a formal, contractual commitment to customers based on one or more SLOs, often with penalties for non-compliance

SLOs serve as the foundation for SLAs. While SLOs are internal benchmarks used by engineering teams to maintain service quality, SLAs are external agreements that formalize these expectations with customers. Typically, SLAs are more conservative than internal SLOs and are designed to provide a buffer and reduce the risk of breach.

An error budget is an amount of acceptable buffer before an SLO is breached. For example, an uptime commitment of 99.9% per month means that a service can be down 43.83 minutes in a month without breaching the SLO. Suppose a service suffers 30 minutes of downtime during the first fifteen days of a month, leaving 13.83 minutes of error budget that the operations team can afford to spend before they fail to meet their objectives.

Error budgets are traded off against the pace of innovation. In other words, a high velocity of code release in a production software environment supports innovation but causes instability. Companies that measure error budgets can course-correct their strategies mid-month. For example, if they have sustained outages in the early part of the month, they would instead focus their efforts on testing and documentation so as to reduce consumption of the Error Budget during the latter half of the month.

Using best practices for setting objectives can improve effective SLO management. SLOs should:

• Be based on meaningful SLIs that reflect user experience
• Set realistic, customer-centric targets
• Include internal stretch goals that exceed public commitments
• Be reviewed regularly and adjusted based on service evolution and user expectations