In this paper we describe a service modeling project done at an IT department that provides IT services to a network of state owned healthcare providers in the state of Vaud in Switzerland. The goal of the project is to un- derstand how to maintain business continuity in the case of a disaster affecting the IT department’s data center. We analyze how to precisely relate the business requirements to the IT operation requirements with the help of the SEAM En- terprise Architecture method. The results are refined service levels and the iden- tification of the required technical architecture.