5 Service models
5.3 Infrastructure as a Service

IaaS (Infrastructure as a service): is a provision model in which an organization outsources the underlying operating systems, security, networking, storage and servers for developing such applications, services, and for deploying development tools, databases, etc. The service provider owns the equipment and is responsible for housing, running and maintaining it. The client typically pays on a per-use basis. Instead of ready-made applications or services, just network is provided; some of the most common uses of IaaS include virtual servers, load balancers, and network connections

IaaS allows organizations and developers to extend their IT infrastructure on an on-demand basis. The cloud provider has pool of virtualized computing resources and storage which the customer organization can take advantage of. This is on demand computing and takes care of the variation in computing peaks. Physically, the pool of hardware resource is pulled from a multitude of servers and networks usually distributed across numerous data centers, all of which the cloud provider is responsible for maintaining. The client, on the other hand, is given access to the virtualised components in order to build their own IT platforms. She does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, and deployed applications; and possibly limited control of select networking components (e.g., host firewalls).

Some benefits of IaaS are:

  • Quick and easy access to enterprise class capabilities,
  • Scalability; resource is available as and when the client needs it and, therefore, there are no delays in expanding capacity or the wastage of unused capacity
  • Simplicity: the provider assumes the facilities management, hardware/software procurement, provisioning, patching, and all the other complex details involved with infrastructure.
  • No investment in hardware; the underlying physical hardware that supports an IaaS service is set up and maintained by the cloud provider, saving the time and cost of doing so on the client side
  • Location independence; the service can usually be accessed from any location as long as there is an internet connection and the security protocol of the cloud allows it
  • Physical security of data centre locations; services available through a public cloud, or private clouds hosted externally with the cloud provider, benefit from the physical security afforded to the servers which are hosted within a data centre
  • Rapid deployment: Little to no time to provision and deploy.

In bigger businesses, the main advantage is the last one; it is more related with timely deployment in supporting short term and unforeseen needs

The main disadvantage of the IaaS is the business risk. Even with extensive diligence, ongoing audits and proactive management, IaaS still requires trust in the vendor infrastructure/operations for availability, data security etc.

Some examples of IaaS providers are

In common with the other two forms of cloud hosting, IaaS can be utilised by enterprise customers to create cost effective and easily scalable IT solutions where the complexities and expenses of managing the underlying hardware are outsourced to the cloud provider. If the scale of a business customer’s operations fluctuate, or they are looking to expand, they can tap into the cloud resource as and when they need it rather than purchase, install and integrate hardware themselves.