Infrastructure as a Service is a model in which an customer outsources infrastructure required.Vendor owns equipment and is responsible for housing, running and maintaining it.Providers of IaaS offer computers – physical or (more often) virtual machines – and other resources.IaaS clouds often offer additional resources such as a virtual-machine disk image library, raw (block) and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles.IaaS-cloud vendors provide resources on-demand from their data centres.If a company rents infrastructure for running its service its called IaaS.IaaS saves cost of procurement and maintenance of hardware.
To deploy their applications, cloud users install operating-system images and their application software on the cloud infrastructure. In this model, the cloud user patches and maintains the operating systems and the application software.
Cloud providers typically bill this services on basis of utility computing means client typically pays on a per-use basis.
• Where demand is dynamic – If your organization’s Infrastructure demand is very volatile then IaaS is best option for your organization.
• IaaS is best option for new organizations who doesn’t want to invest initially in infrastructure.
• If organization is scaling very fast and there is no time to procure hardware.
• Where there is pressure on the organization to limit capital expenditure and to move to operating expenditure
• For specific line of business, trial or temporary infrastructural needs
If organization has regulatory compliance makes the offshoring or outsourcing of data storage and processing difficult then IaaS is not useful. Another scenario where performance of infrastructure then on premise hardware is better then IaaS