1.2 What Is IT Infrastructure?

IT infrastructures have been around for quite a while. But surprisingly enough no generally accepted definition of IT infrastructure seems to exist. I found that many people are confused by the term IT infrastructure, and a clear definition would help them understand what IT infrastructure is, and what it is not.

In literature, many definitions of IT infrastructure are described. Some of them are

• IT infrastructure consists of the equipment, systems, software, and services used in common across an organization, regardless of mission, program, or project. IT Infrastructure also serves as the foundation upon which mission-, program-, and project-specific systems and capabilities are built.1

• All of the components (Configuration Items) that are necessary to deliver IT Services to customers. The IT Infrastructure consists of more than just hardware and software.2

• All of the hardware, software, networks, facilities, etc., that are required to develop, test, deliver, monitor, control, or support IT services. The term IT Infrastructure includes all of the Information Technology but not the associated people, processes, and documentation.3

• Information technology infrastructure underpins the distributed operational and administrative computing environment. Hidden from the application-based world of end users, technology infrastructure encompasses the unseen realm of protocols, networks, and middleware that bind the computing enterprise together and facilitate efficient data flows. Yet information technology infrastructure involves more than just the mechanics of data systems; it also includes people providing support and services.4

• Infrastructure is the shared and reliable services that provide the foundation for the enterprise IT portfolio. The implementation of an architecture includes the processors, software, databases, electronic links, and datacenters as well as the standards that ensure the components work together, the skills for managing the operation, etc.5

Based on these definitions, the term infrastructure seems a bit vague. Let's try to lighten things up a bit.

The word infrastructure originates from the words infra (Latin for “beneath”) and structure. It encompasses all components that are “beneath the structure,” were the structure can be, for instance, a city, a house, or an information system. In the physical world, the term infrastructure often refers to public utilities, such as water pipes, electricity wires, gas pipes, sewage, and telephone lines—components literally beneath a city's structure.

For most people, infrastructure is invisible and taken for granted. When business processes are described by a business analyst, the information used in the process is very important. How this information is managed using IT systems is “below the surface” for the business analyst. They consider IT systems to be infrastructure.

For users of IT systems, applications are important, as they use them every day, but the way applications are implemented or where they are physically deployed is invisible (below the surface) to the users and hence considered infrastructure.

For systems managers, the building in which their servers are hosted and the utility company that delivers the required electricity are considered infrastructure.

So, what infrastructure comprises dependents on who you ask, and what their point of view is.

The scope of infrastructure as used in this book is explained later in this topic.