Revised Infrastructure Model

In one of the first posts on this website I presented an Infrastructure Model. For the book I am writing, this infrastructure model is used as a basis for describing infrastructures. Because the original infrastructure model was created back four years ago i felt is was time for an upgrade on the model. This article (as part of my book) describes the revised infrastructure model.   

IT infrastructures have been around for quite a while. But surprisingly enough no generally accepted definition of IT infrastructure exists. I found that many people were confused by the term IT infrastructure and were in need of a clear definition. It seemed that many people have different ideas about what IT infrastructures consists of.

The definition of infrastructure is in the eye of the beholder. For developers, infrastructure is the platform to run their applications on. For network managers, infrastructure is the collection of all network equipment. For systems administrators, infrastructure is all equipment they manage and for the architect it is the basic layer to build the business services upon.

Many definitions of IT infrastructure exist. The most important ones are:

• IT infrastructure consists of the equipment, systems, software, and services used in common across an organization, regardless of mission/program/project. IT Infrastructure also serves as the foundation upon which mission/program/project-specific systems and capabilities are built. (cio.gov - the website for the United States Chief Information Officers Council)
• All of the components (Configuration Items) that are needed to deliver IT Services to customers. The IT Infrastructure consists of more than just hardware and software. (ITILv2)
• 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. (ITILv3)
• 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. (Technology Governance Board Definition of Information Technology Infrastructure)
• 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 data centers as well as the standards that ensure the components work together, the skills for managing the operation etc. (Goethe University of Frankfurt, http://www.is-frankfurt.de/)

As you can see, the term infrastructure seems a bit vague. Let’s try to lighten things up a bit. The word infrastructure originates from the words infra (meaning beneath) and structure. It encompasses all components that are available “beneath the structure” of 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, electricity, gas, sewage, and telephone services – components literally beneath a city’s structure. So in general infrastructure is a relative term meaning "the structure beneath a structure."

Dependent on where you are, infrastructure is mostly invisible and taken for granted. When business processes are described, the information used in the process is very important. How this information is managed using IT systems however is “below the surface” for the business analyst. He considers IT systems to be infrastructure; managing the information flows. For users of IT systems the applications are important, but the way they are implemented or where they are physically deployed is invisible to them and considered infrastructure. For system managers the building in which their servers are hosted and the electricity company are considered infrastructure.

So what infrastructure is, is dependent on who you ask. In this book by IT infrastructure I mean the components that are needed to run applications upon. Some typical IT infrastructure characteristics are:

• IT infrastructure is usually shared by a multiple applications
• IT infrastructure is more static and permanent than the applications running upon it
• The management of the infrastructure is disconnected from the system management of the applications running on top of it
• The departments owning infrastructure components is different from the department owning the applications running on it

While IT infrastructures are usually shared by multiple applications, this is not always the case. However IT infrastructure includes the idea of an unshared infrastructure, which means every application has its own infrastructure. The key distinction is that while a server might not be physically shared by multiple applications, it shares its management with other servers.

This book uses the following definition of IT infrastructure:

IT infrastructure is the total set of foundation components and non functional attributes that enables applications to function

Infrastructure as used in this book does not contain complex infrastructure services like databases, Java virtual machines, application servers, mail services, Enterprise Service Buses (ESBs) and other middleware. These are considered to be applications and are of such complexity on their own that they need specialized knowledge and staff to manage them. They also tend to have their own lifecycle, disconnected from the infrastructure components.

This book uses the following infrastructure model to visualize and categorize the foundation components and non functional attributes of an IT infrastructure.

(click here for a larger version and reuse information)

This model shows the components from which an infrastructure is built (the horizontal planes). This stack of components is the basis on which applications can run. Vertically, three infrastructure specific non-functional attributes are shown. These attributes are valid for every component in the infrastructure. The non-functional attributes are security, availability and performance. Although many other non-functional attributes can be defined, these three are almost always very important in infrastructure architectures.

All parts of the infrastructure are maintained by performing systems management.

Datacenters

The basis of all IT is hardware that is located in a datacenter facilities. The datacenters layer includes electricity and cooling, raised floors, fire detection and prevention, physical security, etc.

Servers

Servers are the main components in any data center. They include CPUs, memory, local storage, BIOS, expansion slots and ports, etc.

Networking

The network is a very important part of any infrastructure. Dependent on the environment the network can be very complex. It contains routers, switches, NAT, Firewalls, WAN, LAN, dial-in, Internet access, VPN's, etc. On the network application level it contains DNS, DHCP and SNMP.

Storage

Most servers have internal storage, but usually storage these days is external. The storage component contains DAS, NAS, SAN, FC-AL, iSCSI, etc. Also backup and recovery solutions, and ILM and ECM are part of storage.

Virtualization

On the hardware the operating systems can be installed, but nowadays most hardware is virtualized first. The virtualization layer can be on machine level (creating virtual machines on which operating systems are installed), workstation virtualization (like VDI or terminal server solutions), storage virtualization (like disk arrays and virtual LUNs) and network virtualization (like virtual LANs - VLANs).

Operating Systems

Virtual servers run operating systems (OS's). The most popular operating systems are Microsoft Windows, Linux, UNIX and Apple OSX. However, there are a large amount of other operating systems, usually meant for special purposes, like real-time operating systems, or operating systems for embedded systems. Part of this layer is the way the OS's are deployed, tuning OS parameters, as well as management of users, groups, rights and drivers.

End user devices

Workstations are the devices used by end users to work with applications. Workstations include PCs, laptops and mobile devices.

Non-functional attributes (verticals)

Security

IT Security spans all components. IT security is a very large knowledge area. For infrastructure, it concerns mostly about technical solutions, like VPN, IDS, Access Control, Biometrics, Encryption, etc. Procedural security is mostly used in system administration. It spans creating users, access rights, and security demands for new hardware and software.

Availability

Availability contains areas like backup and restore, Disaster recovery, Failover, high availability clustering, Load balancing and replication.

Performance

The performance of an IT infrastructure is almost always very important and consists of areas like scalability, virtualization and high performance clusters.

System Administration

An important aspect is the administration of the environment. This includes procedures for taking systems and applications in production, maintaining systems and troubleshooting. Usually ITIL is used as a methodology for system administration.