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 we 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 our targets, we present a metamodel to describe the characteristics of the Cloud landscape, emphasising on a provider’s perspective. With this meta-model we intend to introduce new modelling concepts towards facilitating the selection of optimal reconfigurations in a timely fashion.