SLAs, SLIs, and SLOs—what are they?

Preamble

What are SLOs?

SLOs are goals you set for the level of system availability you expect, expressed as a percentage over time.

The service level objectives help teams agree on what “available” and “uptime” mean to them. You gauge your availability and dependability using SLOs as a benchmark. An SLO, as described in the preceding example, states that videos in the web application must start playing in less than 2 seconds, 99% of the time over the course of a week.

What are SLIs?

SLIs are the numerical measurements of how users perceive a system’s availability. They are given as a percentage of the number of successful outputs for a level of service. 

Service level objectives (SLOs) are used to describe these service level indicators, but service level indicators (SLIs) show how reliable a system is right now. SLIs can quantify the percentage of requests that were processed faster than a threshold or the percentage of records that enter a pipeline and produce the right value at the other end. The SLI measures the percentage of videos on a website that begin playing in under two seconds, as was mentioned in the earlier example. The SLO will show you how far you are from the goal.

What are SLAs?

The level of service your customers should receive when using your service is outlined in SLAs.

These service level agreements are contracts between service providers and their customers. They spell out what services the service provider will provide and what standards of service the service provider must meet. When SLO commitments are broken, remedies or penalties are described in SLAs.

The earlier example’s web application’s SLOs, the range of services that will be offered, and all of the SLIs—the metrics used to measure performance in relation to the SLOs—will all be included in the SLA. The obligations of the service provider and the client are also covered by the agreement.

Compared to SLOs, the following examples show how SLIs measure the real-time experience of users:

Who uses service levels, SLOs, SLIs, and SLAs?

Service reliability is hard to define and measure for SRE teams, reliability engineers, and cross-functional teams. So that they can easily measure uptime and performance, cross-functional teams need to put together a single, complete view of important metrics for all parts of a service or system.

Service levels help SRE teams and reliability engineers figure out which parts of their applications and infrastructure are most important. In particular, they need to know when one or more parts make functionality available to customers outside the system. These points of intersection are known as system boundaries. Site reliability engineers need to use service level indicators and goals with their metrics at system boundaries to tell the real story of system performance and reliability. 

Establishing service boundaries, choosing which metrics should be SLIs, and figuring out what the SLO compliance requirements should be require a lot of work and thought. Teams frequently give up on projects because of their complexity. In order to quickly establish a baseline for availability and uptime across their entire stack, all of their teams, including reliability engineers and SRE teams, need precise, customized SLIs and SLOs based on historical system performance.

Although managing service levels isn’t always the responsibility of SRE teams and reliability engineers, it frequently falls under their remit. You can set objectives for system performance by monitoring SLIs and connecting them to SLOs. The SRE book from Google says that latency, traffic, errors, and saturation are the four golden signals of service levels. As an example, you could look at an API call and compare the number of successful and unsuccessful requests (the SLI) with the overall percentage of requests (for example, 95%) that must be successful for users to have a good experience.

To better understand how strict of an SLA they can agree to with customers, SRE teams frequently set strict SLOs on critical components within their applications and services. The team can then use error budgets to figure out how fast problems need to be fixed to meet their SLOs. Service levels let teams add up metrics to get a clear picture of uptime, performance, and reliability for the whole organization. Business leaders can get a good idea of how healthy their system is at a glance by using service levels to track compliance across multiple teams, applications, services, etc.

What is service level management?

Service level management means making sure that all of your operational agreements and processes for the quality of services you provide to customers are right. It involves keeping track of service levels and reporting on them, setting up and changing SLOs, figuring out SLIs, making sure SLAs are being met, and reviewing customer feedback.

The shared definition of “availability” among teams, as stated in your SLOs and also reflected in the SLAs with your clients, is the real center of attention. Internal SLOs should be managed by cross-functional teams to make sure that your company meets or beats these agreements.

Benefits of service level management

It is difficult to implement SLO best practices across teams. To define a common language among teams, you need the appropriate data.

Reliability engineers need to quickly set a baseline for availability and uptime across their entire stack and team. To better meet customer-facing SLAs, you need SLOs and SLIs to figure out the limits of the service and get a clear, unified view of how reliable the service is. To improve your environment as a whole, you must be able to report on reliability, SLO compliance metrics, and error budgets.

You’ll experience the following advantages when you use good SLI, SLO, and SLA procedures and a platform for service level management:

• Easy setup: With a one-click setup and suggestions and customizations offered in a straightforward, guided flow, you can automatically establish a baseline of performance and dependability for any service.
• What is reliability in teams? With SLO and SLI recommendations that assist in defining service boundaries, you can avoid time-consuming alignment procedures and automatically establish reliability benchmarks based on current performance metrics in any entity.
• Iterate and get better: Custom views for both service owners and business leaders drive operational efficiency and improve reporting, alerting, and incident management processes. Teams have insight into how specific nodes or services impact system reliability and can quickly take control of their performance with full-stack context and automation through open-source infrastructure-as-code tools like Terraform.
• Establish reliability standards: SLO compliance metrics and error budgets give organizations a way to report on reliability and implement changes across applications, infrastructure, and teams in a cogent manner. Cross-organizational teams have a unified, transparent view of service reliability, and can better comply with customer-facing SLAs.

About Enteros

​​​​Enteros offers a patented database performance management SaaS platform. It finds the root causes of complex database scalability and performance problems that affect business across a growing number of cloud, RDBMS, NoSQL, and machine learning database platforms.