Infrastructure as a service (IaaS) is a form of cloud computing that provides virtualized computing resources over the internet. IaaS is one of the three main categories of cloud computing services, alongside software as a service (SaaS) and platform as a service (PaaS).

IaaS architecture and how it works

In an IaaS model, a cloud provider hosts the infrastructure components traditionally present in an on-premises data center, including servers, storage and networking hardware, as well as the virtualization or hypervisor layer.

The IaaS provider also supplies a range of services to accompany those infrastructure components. These can include detailed billing, monitoring, log access, security, load balancing and clustering, as well as storage resiliency, such as backup, replication and recovery. These services are increasingly policy-driven, enabling IaaS users to implement greater levels of automation and orchestration for important infrastructure tasks. For example, a user can implement policies to drive load balancing to maintain application availability and performance.

IaaS customers access resources and services through a wide area network (WAN), such as the internet, and can use the cloud provider’s services to install the remaining elements of an application stack. For example, the user can log in to the IaaS platform to create virtual machines (VMs); install operating systems in each VM; deploy middleware, such as databases; create storage buckets for workloads and backups; and install the enterprise workload into that VM. Customers can then use the provider’s services to track costs, monitor performance, balance network traffic, troubleshoot application issues, manage disaster recovery and more.

Any cloud computing model requires the participation of a provider. The provider is often a third-party organization that specializes in selling IaaS. Amazon Web Services (AWS) and Google Cloud Platform (GCP) are examples of independent IaaS providers. A business might also opt to deploy a private cloud, becoming its own provider of infrastructure services.

IaaS pros and cons

Organizations choose IaaS because it is often easier, faster and more cost-efficient to operate a workload without having to buy, manage and support the underlying infrastructure. With IaaS, a business can simply rent or lease that infrastructure from another business.

IaaS is an effective model for workloads that are temporary, experimental or that change unexpectedly. For example, if a business is developing a new software product, it might be more cost-effective to host and test the application using an IaaS provider. Once the new software is tested and refined, the business can remove it from the IaaS environment for a more traditional, in-house deployment. Conversely, the business could commit that piece of software to a long-term IaaS deployment, where the costs of a long-term commitment may be less.

In general, IaaS customers pay on a per use basis, typically by the hour, week or month. Some IaaS providers also charge customers based on the amount of virtual machine space they use. This pay-as-you-go model eliminates the capital expense of deploying in-house hardware and software.