The emerging style of cloud computing provides applications, data, and information technology resources as services of a network. The cloud services approach focuses on a positive user experience while shielding the user from the complexity of the underlying technology. Each cloud service progresses through a well-defined life cycle: The cloud service provider defines the cloud services to be offered and exposes them via a service catalog; service requesters instantiate the services, which are managed against a set of service-level agreements; and finally the cloud service is destroyed when it is no longer needed. This paper describes this life cycle and explains the relationship of managing the life cycle of cloud services to traditional ITIL (R) (Information Technology Infrastructure Library) processes as they are present in many data centers today. Furthermore, this paper elaborates on ensembles that provide the hardware infrastructure required to optimally support such flexible and massively scalable cloud services. An ensemble is an autonomically managed pool of like resources that exposes only virtualized resources while hiding the physical infrastructure. This approach allows growing the physical infrastructure with very little or no incremental administration costs.
