--- title: Davide's Code and Architecture Notes - Introducing SLI,... description: This piece explains three core reliability concepts used in software architecture: Service Level Indicator (SLI, the measured metric), Service Level Objective... canonical: https://daily.dev/posts/davide-s-code-and-architecture-notes---introducing-sli-slo-and-sla-k4rwsskva twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Davide's Code and Architecture Notes - Introducing SLI, SLO, and SLA | daily.dev og:description: This piece explains three core reliability concepts used in software architecture: Service Level Indicator (SLI, the measured metric), Service Level Objective... og:url: https://daily.dev/posts/davide-s-code-and-architecture-notes---introducing-sli-slo-and-sla-k4rwsskva og:image: https://api.daily.dev/og/posts/k4RwSsKvA.png og:image:alt: Davide's Code and Architecture Notes - Introducing SLI, SLO, and SLA og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Davide's Code and Architecture Notes - Introducing SLI, SLO, and SLA **[Code4IT](https://daily.dev/sources/code4it)** · 6 min read · 0 upvotes · 0 comments ## Summary This piece explains three core reliability concepts used in software architecture: Service Level Indicator (SLI, the measured metric), Service Level Objective (SLO, the target for that metric), and Service Level Agreement (SLA, the legally binding contract with penalties for non-compliance). It walks through practical examples such as uptime percentages and latency thresholds, how to track SLIs and SLOs via dashboards and fitness functions, and how these concepts influence architectural decisions around scalability, redundancy, monitoring, resource allocation, and cost. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is the difference between SLI, SLO, and SLA? An SLI (Service Level Indicator) is the actual quantifiable measurement of a service aspect, such as uptime percentage or request latency. An SLO (Service Level Objective) is the target goal for that metric, like 99.9% availability. An SLA (Service Level Agreement) is a legally binding contract with a customer that includes penalties for failing to meet agreed service levels. _daily.dev surfaces architecture explainers like this for engineers defining reliability targets and contracts._ ### How can you keep track of Service Level Objectives in a software system? Create a dashboard to measure each defined SLO and send alerts when values approach a breach threshold. Also design the application architecture with SLO targets in mind, for example using asynchronous communication between services or deploying closer to users' locations to reduce latency and meet availability goals. _Engineers balancing latency, uptime, and architecture trade-offs can track practical guidance like this on daily.dev._ ## Similar posts on daily.dev - [5. High Reliability: How Great Software Recovers Gracefully \(Part 2\)](https://daily.dev/posts/5-high-reliability-how-great-software-recovers-gracefully-part-2--cris8hzxn) · Medium · 0 upvotes · 0 comments - [SLO vs SLA: What's the Difference?](https://daily.dev/posts/slo-vs-sla-what-s-the-difference--d9vkmrwtr) · Last9 · 0 upvotes · 0 comments - [Non-Functional Requirements: SLIs, SLOs, SLAs & Error Budgets](https://daily.dev/posts/non-functional-requirements-slis-slos-slas-error-budgets-y1asodvwo) · Medium · 0 upvotes · 0 comments - [Master SLAs Software: Best Practices for Data Engineering Success](https://daily.dev/posts/master-slas-software-best-practices-for-data-engineering-success-ly23y1tyh) · Decube · 0 upvotes · 0 comments --- Tags: [#architecture](https://daily.dev/tags/architecture), [#observability](https://daily.dev/tags/observability), [#sre](https://daily.dev/tags/sre) [View this post on daily.dev](https://daily.dev/posts/davide-s-code-and-architecture-notes---introducing-sli-slo-and-sla-k4rwsskva) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Davide's Code and Architecture Notes - Introducing SLI, SLO, and SLA","url":"https://daily.dev/posts/davide-s-code-and-architecture-notes---introducing-sli-slo-and-sla-k4rwsskva","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/davide-s-code-and-architecture-notes---introducing-sli-slo-and-sla-k4rwsskva"},"datePublished":"2026-10-04T13:06:38.288Z","dateModified":"2026-10-04T13:10:57.429Z","description":"This piece explains three core reliability concepts used in software architecture: Service Level Indicator (SLI, the measured metric), Service Level Objective...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/d966ec4ebeb076c5103753a2b05ea35f?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/d966ec4ebeb076c5103753a2b05ea35f?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Code4IT","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Code4IT","logo":"https://media.daily.dev/image/upload/s--OaaG4G10--/f_auto,q_auto/v1791119049/logos/code4it?_a=BAMAMicg0","url":"https://daily.dev/sources/code4it"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/davide-s-code-and-architecture-notes---introducing-sli-slo-and-sla-k4rwsskva","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"architecture,observability,sre","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Code4IT","item":"https://daily.dev/sources/code4it"},{"@type":"ListItem","position":3,"name":"Davide's Code and Architecture Notes - Introducing SLI, SLO, and SLA"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/davide-s-code-and-architecture-notes---introducing-sli-slo-and-sla-k4rwsskva#faq","mainEntity":[{"@type":"Question","name":"What is the difference between SLI, SLO, and SLA?","acceptedAnswer":{"@type":"Answer","text":"An SLI (Service Level Indicator) is the actual quantifiable measurement of a service aspect, such as uptime percentage or request latency. 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