What is Infrastructure as a Service (IaaS)?
Infrastructure as a Service (IaaS) is a cloud computing model in which a provider offers virtualised computing resources — servers (virtual machines), storage, and networking — over the internet on a pay-as-you-go basis, while the customer manages the operating system, applications, and data.
Infrastructure as a Service (IaaS): Full Explanation
IaaS is the most fundamental cloud service model. The provider owns and maintains the physical data centre hardware; you rent virtualised slices of that hardware and manage everything above the hypervisor layer.
The three main cloud service models form a responsibility stack: IaaS (you manage OS, runtime, applications, data), PaaS (provider manages OS and runtime; you manage applications and data), SaaS (provider manages everything; you just use the application).
IaaS gives the most control and flexibility — you can install any operating system, runtime, or application. It also requires the most management: patching OSes, managing storage, configuring networks. It's the right choice when you have specialised software requirements, need granular control over your environment, or are "lifting and shifting" on-premise workloads to the cloud.
Key Facts About Infrastructure as a Service (IaaS)
- ✓IaaS examples on AWS: EC2 (virtual machines), EBS (block storage), VPC (networking).
- ✓IaaS examples on Azure: Virtual Machines, Azure Blob Storage, Virtual Network.
- ✓IaaS examples on GCP: Compute Engine, Cloud Storage, VPC.
- ✓You are responsible for OS updates, security patching, and application configuration on IaaS.
- ✓PaaS (e.g. AWS Lambda, Azure App Service) reduces management overhead by handling the OS and runtime.
- ✓SaaS (e.g. Office 365, Salesforce) provides complete applications with no infrastructure management.
Real-World Example: IT Services
An IT services company migrated their client's legacy ERP system to AWS IaaS. Using EC2 virtual machines, they replicated the existing server configuration with minimal application changes ("lift and shift"). The client's IT team retains full control of the OS and application stack, while eliminating data centre maintenance costs and gaining on-demand scalability for quarterly processing peaks.
Frequently Asked Questions
What is the difference between IaaS, PaaS, and SaaS?
IaaS: you rent virtual hardware and manage everything above it. PaaS: you rent a managed platform (runtime, OS) and only manage your code and data. SaaS: you use a complete application managed by the provider. The choice depends on how much control vs convenience you need.
Is IaaS cheaper than PaaS?
IaaS often has lower raw unit costs but requires more staff time to manage. PaaS costs more per compute unit but eliminates OS management, patching, and scaling configuration. Total cost of ownership (TCO) including staff time usually favours PaaS for most application workloads.
Can I run AI workloads on IaaS?
Yes. GPU-accelerated IaaS instances (AWS P3/P4, Azure NCv3, GCP A100) are used for ML training workloads. For inference and managed AI services, PaaS offerings (SageMaker, Azure ML, Vertex AI) are more practical as they manage the ML infrastructure layer.