menu Main menu move to sidebar hide Navigation Main page Contents Current events Random article About Wikipedia Contact us Contribute Help Learn to edit Community portal Recent changes Upload file Special pages Search Search Appearance Donate Create account Log in Personal tools Donate Create account Log in Contents move to sidebar hide (Top) 1 Overview 2 Examples 3 Term usage 4 References 5 External links Toggle the table of contents Service-level objective 3 languages Français Lietuvių 中文 Edit links Article Talk English Read Edit View history Tools Tools move to sidebar hide Actions Read Edit View history General What links here Related changes Upload file Permanent link Page information Cite this page Get shortened URL Print/export Download as PDF Printable version In other projects Wikidata item Appearance move to sidebar hide From Wikipedia, the free encyclopedia Key element of a service-level agreement A service-level objective ( SLO ) is a target value or range of values for a service level that is measured by an SLI . [ 1 ] An SLO is a key element of a service-level agreement (SLA) between a service provider and a customer . SLOs are agreed upon as a means of measuring the performance of the service provider and are outlined as a way of avoiding disputes between the two parties based on misunderstanding. Overview [ edit ] There is often confusion in the use of SLAs and SLOs. The SLA is the entire agreement that specifies what service is to be provided, how it is supported, times, locations, costs, performance, and responsibilities of the parties involved. SLOs are specific measurable characteristics of the SLA such as availability, throughput, frequency, response time, or quality. These SLOs together are meant to define the expected service between the provider and the customer and vary depending on the service's urgency, resources, and budget. SLOs provide a quantitative means to define the level of service a customer can expect from a provider. [ 2 ] The SLO are formed by setting goals for metrics (commonly called service level indicators , SLIs). As an example, an availability SLO may be defined as the expected measured value of an availability SLI over a prescribed duration (e.g. four weeks). The availability SLI used will vary based on the nature and architecture of the service. For example, a simple web service might use the ratio of successful responses served vs the total number of valid requests received. (total_success / total_valid) [ 3 ] Examples [ edit ] Sturm and Morris argue [ 4 ] that SLOs must be: Attainable Repeatable Measurable Understandable Meaningful Controllable Affordable Mutually acceptable While Andrieux et al. define the SLO as "the quality of service aspect of the agreement. Syntactically, it is an assertion over the terms of the agreement as well as such qualities as date and time". [ 5 ] Keller and Ludwig more concisely define an SLO as "commitment to maintain a particular state of the service in a given period" with respect to the state of the SLA parameters. [ 6 ] Keller and Ludwig go on to state that while service providers will most often be the lead entity in taking on SLOs there is no firm definition as such and any entity can be responsible for an SLO. Along with this an SLO can be broken down into a number of different components: Obliged – The entity that is required to deliver the SLO. Validity period – The time in which the SLO will be delivered. Expression – This is the actual language that defines what the SLO will be. Optionally an EvaluationEvent maybe assigned to the SLO, an EvaluationEvent is defined as the measure by which the SLO will be checked to see whether it's meeting the expression. SLOs should generally be specified in terms of an achievement value or service level, a target measurement, a measurement period, and where and how they are measured. [ 2 ] As an example, "90% of calls to the helpdesk should be answered in less than 20 seconds measured over a one-month period as reported by the ACD system ". Results can be reported as a percent of time that the target answer time was achieved and then compared to the desired service level (90%). Type of measure Example SLO requirement Measurement period Availability The application will be available 99.95% of the time Over a year Service-desk response 75% of help desk calls will be answered in less than a minute 85% of help desk calls will be answered within two minutes 100% of help desk calls will be answered within three minutes Over a month Incident response time 99% of severity 1 tickets will be resolved within three hours 98% of severity 2 tickets will be resolved within eight hours 98% of severity 3 tickets will be resolved within three business days 98% of severity 4 tickets will be resolved within five business days Over a quarter Response time 85% of TCP replies within 1.5 seconds of receiving a request 99.5% of TCP replies within 4 seconds of receiving a request Over a month Term usage [ edit ] The SLO term is found in various scientific papers, for instance in the reference architecture of the SLA@SOI project, [ 7 ] and it is used in the Open Grid Forum document on WS-Agreement. [ 5 ] References [ edit ] ^ Jones, Chris; Wilkes, John; Murphy, Niall. Betsy Beyer (ed.). "Site Reliability Engineering: How Google Runs Production Systems" . Google Site Reliability Engineering . O'Reilly . Retrieved 9 June 2023 . ^ a b Rastegari, Yousef; Shams, Fereidoon (2015-12-29). "Optimal Decomposition of Service Level Objectives into Policy Assertions" . The Scientific World Journal . 2015 (1) 465074. doi : 10.1155/2015/465074 . ISSN   2356-6140 . PMC   4709918 . PMID   26962544 . ^ Hidalgo, Alex (August 2020). Implementing Service Level Objectives (1 ed.). O'Reilly Media, Inc. ISBN   978-1-4920-7676-6 . ^ Rick Sturm, Wayne Morris "Foundations of Service Level Management", April 2000, Pearson. ^ a b Alain Andrieux, Karl Czajkowski, Asit Dan, Kate Keahey , Heiko Ludwig, Toshiyuki Nakata, Jim Pruyne, John Rofrano, Steve Tuecke, Ming Xu "Web Services Agreement Specification (WS-Agreement)", GFD-R-P.107, March 2007, Open Grid Forum. ^ Alexander Keller, Heiko Ludwig "The WSLA Framework: Specifying and Monitoring Service Level Agreements for Web Services", Journal of Network and Systems Management, Vol. 11, n. 1, March 2003. ^ Jens Happe, Wolfgang Theilmann, Andrew Edmonds, and Keven T. Kearney "A Reference Architecture for Multi-Level SLA Management" in "Service Level Agreements for Cloud Computing", eds. Wieder, Philipp and Butler, Joe M. and Theilmann, Wolfgang and Yahyapour, Ramin, Springer New York, 2011, DOI:10.1007/978-1-4614-1614-2_2 External links [ edit ] Service Level Objectives What are SLOs? How service-level objectives work with SLIs to deliver on SLAs SLA vs. SLO vs. SLI: What's the difference? Retrieved from " https://en.wikipedia.org/w/index.php?title=Service-level_objective&oldid=1340771941 " Categories : IT service management Outsourcing Hidden categories: Articles with short description Short description matches Wikidata This page was last edited on 27 February 2026, at 15:50  (UTC) . Text is available under the Creative Commons Attribution-ShareAlike 4.0 License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy . Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc. , a non-profit organization. Privacy policy About Wikipedia Disclaimers Contact Wikipedia Legal & safety contacts Code of Conduct Developers Statistics Cookie statement Mobile view Search Search Toggle the table of contents Service-level objective 3 languages Add topic