SLA Design from a Business Perspective

A method is proposed whereby values for Service Level Objectives (SLOs) of an SLA can be chosen to reduce the sum IT infrastructure cost plus business financial loss. Business considerations are brought into the model by including the business losses sustained when IT components fail or performance is degraded. To this end, an impact model is fully developed in the paper. A numerical example consisting of an e-commerce business process using an IT service dependent on three infrastructure tiers (web tier, application tier, database tier) is used to show that the resulting choice of SLOs can be vastly superior to ad hoc design. A further conclusion is that infrastructure design and the resulting SLOs can be quite dependent on the “importance” of the business processes (BPs) being serviced: higher-revenue BPs deserve better infrastructure and the method presented shows exactly how much better the infrastructure should be.