As Cloud Computing becomes more predominant, large scale datacenters are subject to an increasing demand for efficiency and flexibility. However, growing infrastructure management complexity and maintenance costs are becoming a hindrance to the advancement of the Cloud vision. In this paper, the authors discuss how existing datacenter resource management approaches fail to provide infrastructure elasticity and suggest a resources provisioning architecture to fill this gap. As a first step towards implementing their targets, they present a metamodel to describe the characteristics of the Cloud landscape, emphasizing on a provider's perspective. With this meta-model they intend to introduce new modeling concepts towards facilitating the selection of optimal reconfigurations in a timely fashion.