What Is an SLA?
An SLA (Service Level Agreement) is a formal document that defines the quality, scope, and responsibilities of a service between an IT service provider and a customer. The answer to the question "An incident was reported — how quickly will support arrive?" is found in the SLA.
Core SLA Metrics
Response Time
The time elapsed from when a support request is received until the first response is given. Covers notifications received via phone, email, or a ticketing system.
Resolution Time
The maximum time defined for resolving an issue. Varies according to the severity level of the problem.
Uptime Guarantee
Specifies the minimum time a service must be available.
- 99.9% — Maximum 8.7 hours of downtime per year
- 99.5% — Maximum 43.8 hours of downtime per year
- 99% — Maximum 87.6 hours of downtime per year
Priority Levels
In enterprise SLA agreements, issues are typically divided into four levels:
| Level | Definition | Response Time | Resolution Time |
|---|---|---|---|
| P1 — Critical | Entire system down, operations halted | 15 minutes | 4 hours |
| P2 — High | Critical system affected | 1 hour | 8 hours |
| P3 — Medium | Partial impact, temporary workaround available | 4 hours | 2 business days |
| P4 — Low | Minor issue, operations continue | 1 business day | 5 business days |
What a Good SLA Should Contain
Scope definition: Which systems are covered and during which hours must be clearly stated. The difference between "24/7 support" and "weekday 09:00–18:00 support" is critical.
Escalation procedure: How an issue is escalated when the resolution time is exceeded must be defined.
Reporting: Monthly or quarterly SLA performance reports enable monitoring of service quality.
Penalty clauses: In the event of an SLA breach, remedies such as service credits, discounts, or compensation must be included in the contract.
Exclusions: Exclusion conditions such as planned maintenance windows, natural disasters, or third-party-caused outages must be clearly defined.
Reactive or Proactive?
Traditional SLAs are reactive: an incident occurs, is reported, and is resolved. In modern managed IT services, the proactive SLA approach is becoming prominent:
- Systems are continuously monitored; issues are detected before they occur
- Periodic maintenance is planned
- Capacity planning and hardware lifecycle tracking are carried out
With a proactive approach, the majority of P1 incidents are prevented before they happen.
How to Define the Right SLA for Your Organization?
- Business criticality: How much revenue would be lost if your server were down for 1 hour?
- Working hours: Is after-hours support necessary?
- Technician access: Is remote support sufficient, or is on-site support required?
- Budget: Shorter resolution times come with higher service fees.
Conclusion
An SLA is the most frequently overlooked yet most critical document in IT service procurement. Vague or incomplete SLA terms lead to "whose responsibility is this?" disputes during an outage and prolonged downtime. As NRC Sistem, we provide our customers with SLA agreements that include clear priority levels, measurable response times, and regular reporting.