Cloud computing is an attractive computing model since it allows for resources to be provisioned according on a demand basis, i.e., cloud users can rent resources as they become necessary. With Infrastructure as a Service (IaaS), IT services can be delivered as a subscription service, eliminating up-front costs and driving down ongoing support costs. As with managed hosting, IaaS providers keep costs low by pooling resources and giving customers access to a shared facility. But a major difference is that IaaS resources are elastic and available on a self-service, on-demand basis. The convergence of those trends, with other advances of the last several years, has made it possible to take infrastructure outsourcing to a new level.