SLA 是服务提供商和客户之间的协议，服务提供商在服务的质量、可用性和响应速度之类的 服务级别目标 上作出承诺，若不达标将作出赔偿。
An SLA normally involves a promise to someone using your service that its availability SLO should meet a certain level over a certain period, and if it fails to do so then some kind of penalty will be paid. This might be a partial refund of the service subscription fee paid by customers for that period, or additional subscription time added for free.
A service-level agreement (SLA) is a commitment between a service provider and a customer. Particular aspects of the service – quality, availability, responsibilities – are agreed between the service provider and the service user.