The cloud operation models can be distinguished by property, business and organizational aspects.


The above referenced cloud operation models aren’t distinguished by the technical structure. Virtualization, the x-as-a service concept and the delivery over the internet are the main elements for the technical implementation Private cloud - Private cloud is an intra-organizational-cloud environment and is self-provisioned. The access is limited only to employees, authorized business partners, customers and suppliers. The Web-Access is usually designed without any time limitation and is locally independent. The reason for using such cloud solutions are the unique requirements of the business, very high security-policy and high requirements of governance in the sense of regulation and legislation.


Public cloud - Public Cloud is owned, located and operated by a public IT service provider.


Access is usually over the internet. Many customers share a virtualized infrastructure platform. A public cloud provides a choice of highly standardized business process application and infrastructure services on a variable, usage-based basis (BITKOM, Cloud Computing - Evolution in der Technik - Revolutionim Business, 2011, p. 30) . The usage of the platform is by many, from each other independent parties (multi-tenancy concept). The reasons for using such models are low TCO (total cost of ownership), high flexibility and scalability (elasticity) and a usage-dependant (pay-per-use) concept. The disadvantages are that service is “out-of-the-box” and handicaps company-specific adoptions and differentiation in the market and decreasing level of security because of the shared usage of the IT capabilities.


Hybrid cloud - is a combined usage of private and public cloud solutions with the combination of the conventional IT-structure. The advantage is the balance between security, proprietary, compliance and cost requirement.