Service Level Objective (SLO) - definition & overview

SLOs, through Service Level Indicators (SLIs), make it easier for DevOps and site reliability engineering (SRE) teams to evaluate and assess how well their services are being maintained and how well their SLA is being upheld. The SLO framework governs how these teams discuss the reliability of a system or necessary changes.

A Service Level Objective (SLO) is an important aspect of a Service Level Agreement (SLA), which represents an agreement between a service provider and or client. The SLA guarantees to a client that your technology’s SLO should maintain a certain standard or level of service over time. If it fails to meet such a standard, then the service provider will pay a penalty. The management of SLOs is how an SLA is maintained and measured.

The success of any technology is based on one thing: a positive or acceptable user experience.

Building an exceptional digital customer experience requires an understanding of the metrics that comprise the service’s performance. An application or software is essentially providing a service to a user or, more often, millions of users. So how do companies evaluate the efficacy and quality of their services from the user's perspective?

This is where service SLOs come in. Let’s look at the key components of an SLO.

• When someone is obliged, this refers to the entity or group that is required to deliver and maintain their SLO.

• The validity period refers to the period in which the SLO must be delivered. Anything delivered beyond that is a breach of the SLA.

• The expression refers to the language that delineates what the SLO is and how it is to be met.

• Quality of service (QoS) is made through various measurements (SLIs) that, when put together, represent a numerical SLO achievement value, usually in the form of percentiles

These various aspects of the SLO must all be maintained for the initial SLA to be upheld.

SLAs, SLOs and SLIs all work together to uphold the contract and agreement between a service provider and a client. Below we’ll look at each term and see how it functions in the client–service provider relationship.

• SLA: An obligation, or set of obligations made between a service provider and a client, which guarantees certain quality assurances concerning availability, responsibility, and other key metrics. Different types of SLAs define various levels of agreements, including customer-based SLA, service-based SLA, and corporate-level SLA. SLOs, the next subsection of the SLA umbrella, often define SLAs.
  

• SLO: An important aspect of how we measure and maintain the obligations defined in an SLA. SLOs are essentially the percentage we place on specific metrics that demonstrate how effectively the agreements within an SLA are being upheld. SLOs are expressed through specific, concrete numerical percentiles that represent and measure the efficacy of a specific level of service. Those numbers are representative of the next sub-category, SLIs.

• SLI: A specific metric that helps companies measure some aspect of the level of services to their customers. SLIs can help companies identify ongoing network issues and lead to more efficient recoveries. SLIs are typically measured as percentages, with 0% being terrible performance to 100% being perfect performance. SLIs are the foundation of SLOs, which aim to represent the objectives that an organization is aiming to uphold within its SLA. SLOs will determine which SLIs are critical to be measured and used to demonstrate quality assurance.

SLOs are specified in terms of a defined target level, measurement, and achievement over a determined time or quality level. An SLO example might look something like this: 95% of all requests should be resolved within 24 hours of the initial point of contact. The point of the SLO is to ensure that a level of satisfaction is maintained with clients, customers, and users, and the percentile method is a simple framework that allows for a concrete demonstration of quality and service reliability.

Below are some common SLIs that comprise the SLOs companies are measuring:

• Availability
  Availability is another important SLI that measures the fraction of time that a service is available. Availability is connected to and often determined in terms of yield, another SLI. An example of an availability measurement might be that a service or application is available 98% of the time.

• Service desk response
  Service desk response looks at how quickly a help desk question or request is responded to. The less amount of time it takes to respond to a request, the higher your percentage will be. For example, you can create an objective that states 90% of help desk requests will be responded to in less than three minutes.

• Incident response time
  Incident response, like service desk response, measures how quickly incidents and issues are resolved. An example of this might be that 95% of incidents will be resolved within four hours.

• Error rate
  Error rates are another key SLI, and they measure, as you may have guessed, the number or level of errors throughout the customer experience. A low error rate, let’s say at 5%, would be a good thing and represent an SLO at 95%. Teams often leverage error budgets to balance service reliability with service innovation.

It’s important to remember that there are many types of SLOs that you can use to measure your quality of services. It’s best not to capitalize on each SLO at your disposal, but to narrow your focus down to the SLOs that matter most to your clients and users. Depending on your client/user, you might take a product-based approach, customer-service-based approach, or engineering approach.

Businesses are focused on achieving their goals and maintaining their SLAs, which is why they value robust observability platforms, like Sumo Logic, to help them measure their objectives and ensure they’re on track to meeting their KPIs, deadlines, and long-term strategies.

Try Sumo Logic’s free trial today to see how we can help you reach your goals and deliver the digital customer experience today.