Optimizing IT Service Costs with Respect to the Availability Service Level Objective

Meeting the availability service level objective while minimizing the costs of the IT service provision is a major challenge for IT service designers. In order to optimize component choices and redundancy mechanisms, the redundancy allocation problem (RAP) was defined. RAP solution algorithms support decision makers with (sub)optimal design configurations that trade-off availability and costs. However, the existing RAP definitions are not suitable for IT service design since they do not include inter-component dependencies such as common mode failures. Therefore, a RAP definition is provided in this paper in which the characteristics of modern IT systems such as standby mechanisms, performance degradation and generic dependencies are integrated. The RAP definition and an adapted genetic algorithm are applied to optimize the costs of an excerpt of an application service provider's IT system landscape. The results demonstrate that the developed approach is applicable and suitable to minimize IT service costs while fulfilling the availability guarantees that are documented in service level agreements.