A service level agreement (SLA) specifies minimum performance requirements and, upon failure to meet those requirements, the level and extent of customer support that must be provided. A service level agreement is based on business requirements defined during business analysis, which are later specified as service level requirements during the technical requirements phase. The SLA is signed during project approval, which occurs in the deployment design phase.
You should develop an SLA around areas such as uptime, response time, message delivery time, and disaster recovery. An SLA should account for items such as an overview of the system, the roles and responsibilities of support organizations, how to measure service levels, change requests, and so forth. Identifying your organization’s expectations around system availability is key in determining the scope of an SLA.