Data center
A data centre is a facility used for housing a large amount of electronic equipment, typically computers and communications equipment. As the name implies, a data centre is usually maintained by an organization for the purpose of handling the data necessary for its operations. A bank for example may have a data centre, where all its customers' account information is maintained and transactions involving this data are carried out. Practically every company mid-sized and upwards has some kind of data centre, and large companies often have dozens of data centres.
As data is a crucial aspect of most organizational operations, organizations tend to be very protective of their data. A data center must therefore keep high standards for assuring the integrity and functionality of its hosted computer environment. This is depicted in its physical and logical layout.
Prior to and during the dot com crash, thousands of square feet of general-purpose data centres were built in the hope of filling them with servers for web hosting and application service providers. This demand went largely unrealised.
A colocation centre is a type of data centre.
Physical Layout
A data center can occupy one room of a building, one or more floors, or up to the whole building. Most of the equipment is often in the form of 1U servers (so-called "pizza boxes") racked up in 19 inch rack cabinets, which are usually placed in single rows forming corridors between them. This allows people access to the front and rear of each cabinet. Some equipment such as mainframe computers and Air conditioning is used to keep the room cool, generally around 17 degrees Celsius. This is crucial since electronic equipment in a confined space generates much excess heat, and tends to malfunction if cooling is not handled.
- Backup power is often available. This can include one or more uninterruptible power supplies and diesel generators located close by.
- Data centres typically have raised floors made up of 2 foot (600mm) removable square tiles. These allow (in theory) all data and power cabling to be laid neatly and safely in cable trays below.
- Data centres often have elaborate fire prevention and fire extinguishing systems. Using water on operational electrical equipment can do just as much damage as a fire so using it is not an option - also ordinary water and electricity don't mix well. Originally halon gas was used in the event of a fire to extinguish flames. It is an inert gas that pushes all the oxygen out of the room. However this has now been banned in some countries because of the danger it poses to people if they are trapped in the same room without oxygen. More recent alternatives include Argonite and FM200, and even systems based on ultra-pure water.
- Physical security also plays a large role with data centres. Personal access to the site is usually restricted to a select few. Video camera survellience and permanent security guards are almost always present if the data centre is large or contains sensitive information on any of the systems within.
Network Infrastructure
Communications in data centres today are most often based on networks running the IP protocol suite. Data centers contain a set of routers and switches that transport traffic between the servers and to the outside world.
Some of the servers at the data centre are used for running the basic Internet and intranet services needed by internal users in the organization: email servers, proxy servers, DNS servers, etc.
Network security elements are also usually deployed: firewalls, VPN gateways, Intrusion detection systems, etc. Also common are monitoring systems for the network and some of the applications.
Applications
The main purpose of a data centre is running the applications that handle the core business and operational data of the organization. Such systems may be proprietary and developed internally by the organization, or bought from enterprise software vendors. Such common applications are ERP and CRM systems.
Often these applications will be composed of multiple hosts, each running a single component. Common components of such applications are databases, file servers, application servers, and middleware.
