IT Infrastructure model
31 August 06 - 10:22
Area: default - Link to this article
Note: Four years after this post I created a revised version of this infrastructure model. It is published at this link!
Business management, system administrators, project leaders, architects and developers all have a different perception on IT infrastructure (if they have a perception about it at all).
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 she manages and for the IT architect it is the basic layer to build the business services on.
Because everyone has a different idea on what infrastructure is, I think it is good to introduce a definition of IT infrastructure:
IT infrastructure is the total set of components that enables applications to function
The following model can be used to visualize the various components.
All yellow planes in the model are part of the infrastructure. Middleware is usually the borderline between infrastructure and applications.
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.
A network of servers consists of hardware. Servers run operating systems. They use storage through a network. Networks are also used to let operating systems communicate with the upper layers and with other infrastructure stacks. The operating systems run middleware, which is used by applications.
Vertically, viewpoints are shown. Viewpoints are part of every component. The viewpoints are security, availability and systems management.
Around the infrastructure, the middleware and the applications, lies the IT architecture. An infrastructure architect is responsible for a consistent implementation of the whole IT infrastructure, so it aligns with the upper layer business processes. After all, supporting the business is the main goal of IT architecture.
The proposed model can be used to describe an infrastructure environment. Below I will shortly describe all components and viewpoints.
Components (horizontals)
Hardware
The basis of all IT is hardware. Infrastructure starts with hardware needed to run applications. Hardware contains among others: servers, network components and disk storage. Hardware includes electricity and cooling, as well as cabelling, patching, labeling, racks, vibrations, etc.
Operating Systems
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. Also virtualization is part of this layer.
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.
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.
Middleware
Middleware is either part of the infrastructure or part of applications (dependent on the type of middleware). Examples of middleware that fall under infrastructure are: DNS severs, Mail servers, DHCP servers, Proxy servers, Web servers, etc. Examples of application-type middleware are: Databases, Java container servers, EAI solutions, etc.
Applications
Applications are no part of the infrastructure.
Views (verticals)
Security
IT Security is a view that 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, Clustering, Load balancing and replication.
System Administration
An important aspect is the administration of the environment. This view includes procedures for taking systems and applications in production, maintaining systems and troubleshooting.
Usually ITIL is used as a methodology for system administration.
There is also a 
Master Certified IT Architect
CISSP (Certified Information Systems Security Professional)
TOGAF Certified Architect