Infrastructure-as-a-service (IaaS) is one of the three main categories of cloud computing service. The other two are Platform-as-a-service (PaaS) and Software-as-a-service (SaaS) which rest on the top of the IaaS layer.
Infrastructure as a service which is also referred as Cloud Infrastructure service is a way of delivering Infrastructure service offering on demand basis. Clients can use infrastructure offerings such as – hardware, servers (cloud server), computing, storage (storage on cloud), networking components and operating systems on an on-demand basis rather than purchasing them.
ll the IaaS providers share a few common characteristics which are fundamental to this service:
- Uses virtualization techniques to enable leasing of resources
- The services are provided on demand
- Easy to use remote interfaces to use infrastructure
- They provide services on pay as you go model
Exhibit 1: Cloud Computing Service offerings – SaaS, PaaS and IaaS
Some examples of the IaaS sub-services are:
- DBaaS: Database access and use of a database management system as a service
- STaaS: Data Storage as a service, including database-like services
- CCaaS: Compute Capacity (CPUs) as virtual services based on on-demand usage
IaaS is evolved from virtual private server offerings. IaaS is basically delivering computer infrastructure, typically a platform virtualization environment, as a service. IaaS service provider owns the physical assets and they provide provisioning, running and maintaining services on demand.
Key advantages of IaaS:
Some of the key advantages of IaaS include -
- Save money – IaaS converts capital expenditures into operational expenses. Thus, one does not have to upfront spend money on IT infrastructure.
- Increased Flexibility – Dynamic scale up and scale down ensure flexibility in resources and pay-as-you-go services provides flexibility in using the services
- Increased focus – With IaaS, IT workforce can focus more on results and value adds rather than infrastructure working and maintenance.
IaaS Pricing and Billing: IaaS can be availed on a pay-per-use basis or on a flat rate basis
- Pay-per use model – metered service; pay for the infrastructure services that applications are using; usually charges are based on throughput but some vendors charge for server time as well.
- Flat rate model – Flat rate on a monthly, quarterly or annual basis for a subscribed configuration