Whether you are studying for a cloud certification or working to migrate on-premises IT to the cloud, three terms you will constantly hear are IaaS, PaaS, and SaaS. These three concepts can be easy to confuse at first, yet they are the backbone of the cloud model. no matter which vendor you choose.
The three terms work together, representing different levels of responsibility of the cloud provider and the customer.
Understanding the requirements of on-premise is necessary to fully understand the advantages of cloud. Most companies considering migrating to the cloud may already have on-premises IT infrastructure, such as servers, storage, and networks. This equipment needs to be stored physically on location and required a dedicated IT staff to manage everything for their equipment.
Who Manages What?
|Identity||You||You||Both / Mixed||Both / Mixed|
|Runtime & Middleware||You||You||Cloud Provider||Cloud Provider|
|Operating System||You||You||Cloud Provider||Cloud Provider|
|Virtualization||You||You||Cloud Provider||Cloud Provider|
|Servers / Compute||You||Cloud Provider||Cloud Provider||Cloud Provider|
|Storage||You||Cloud Provider||Cloud Provider||Cloud Provider|
|Networking||You||Cloud Provider||Cloud Provider||Cloud Provider|
Infrastructure-as-a-Service is the largest category of cloud services. With IaaS, the customer is given control of the hardware and everything above it - giving the customer the most management responsibility. IaaS is effectively the renting of hardware, such as paying monthly for Virtual Machines and Storage versus buying servers and storage devices.
This model offers the advantage of giving customers near full control of equipment without the requirement for a physical location for equipment, nor electricity and equipment purchasing costs. When using IaaS offerings, customers only pay for what resources they use, typically paying per hour for resources used.
PaaS exists between IaaS and SaaS, giving the customer a smaller management footprint by taking care of the operating system and any middleware, but without providing a finished end-user software product. This category of software is usually targeted are developers, where they are still responsible for developing their applications but without the need to manage OS, networks, etc.
The last service type is Software-as-a-Service(SaaS). SaaS offerings are complete versions of software you typically pay for monthly or annually. SaaS doesn't require any development from the customer and very minimal management - typically limited to account management and providing data. Examples of SaaS products include accounting tools, cloud office suites and other end-user facing business applications.