Often, within server farms, are made up of cluster systems in a better way to manage heavy workloads or critical (mail server, web, database, rendering, GRID ...).

It is not uncommon, in fact, find a server farm made up of hundreds, if not thousands of servers. The realization of a server farm allows you to spread the cost of building and operating a secure and reduce costs for connectivity.
When the server farm are made with a view to hiring the space, it is called Data Center or Network Operating Center (NOC).

Usually computers in a web farm are controlled by a chief administrator, also called "senior administrator", and his working group, who are responsible for the proper operation of the farm, also in terms of computer security and general.

Services
Providers offer various services through the web farm
Hosting
Consist to install your application (web or not) in the provider's servers owned and operated by the provider. It is the least expensive but also less powerful, since each machine can be installed in many applications.
Virtual Servers
The provider makes available a virtual machine located on one physical server (which will contain other machines). Thus, the customer can manage as he wants his virtual machine, and the provider is dedicated to the physical machine. The customer is given the opportunity to choose the amount processor, memory, and disk speed / bandwidth. The amount of resources is not very high because they have to live on the physical server other virtual machines. This solution is suitable for short intensive applications.
Dedicated Server
In this formula, the customer buys (or rents) a physical server, and pay only the costs of location of the server (and any rental charges). The administration server software is fully charged and availability of the customer. The advantage of buying the server webfarm is that in case of failure, the provider can supply any spare parts at short notice.
Housing and Colocation
Here the customer purchases the server somewhere else and he takes care of physical problems and software. Webfarm to pay only the price of placement (power, network, etc..).

Equipment

Wiring
It is of vital importance in a web farm. The voltage must be provided 24 hours a 24-day, 365 days a year. A sudden absence would cause an immediate shutdown of all servers and all network infrastructure, making it difficult to restart, often performed locally. Also, the frequency must be very stable, as well as all the protections of a short circuit or overload.

For these reasons, a web farm has many UPS that are activated as soon as it loses power from the grid. During this period, an automated process initiated by diesel generators, which takes us a few minutes to get into full swing. At this point the current is supplied by the generators which have autonomy of a few days. UPS devices are also used to smooth the voltage and frequency.

The voltage is then distributed to the cabinets, each of which has a circuit breaker and a circuit breaker in order to prevent a short-circuit can shut down the entire farm. The major breakdowns due to the electrical system are obtained by a malfunction of the UPS or generators, which causes a complete shutdown of an area of the farm.
Plant anti-fire and anti-flooding
Water and fire are two destructive elements for a web farm. The first cause various cortocitcuiti to all electronic components. In order to avoid flooding, the work area is built on a raised floor and below it are ready pumps that expel water from the area server.

The second problem is much more heartfelt. Rooms full of electrical components that can go into every moments short time are very dangerous. All racks are fully fire retardant and in each room there is a fire extinguishing system. There are various types of shutdown, usually using inert gases (water, of course, you can not use) that switch a few seconds after the sensors of smoke and flame pointed to the risk of fire. When danger is detected a siren warns all present to leave the room to avoid risk of suffocation, due to the replacement of the air with the gas turned off. In reality it never happens completely, while still allowing the survival of the people inside.
Air conditioning
Each rack needs to be cooled. The temperature must not fall below 10 ° C and not exceed 28 ° C, the best value is around 20 ° C [1] For this webfarm are equipped with air conditioning, centralized or located in any room and controlled through specialized software which make use of the measurements made by the different sensors in the closets and rooms.
Connectivity
The majority of servers allocated in a web farm contains applications that require to go online. A server farm must be equipped with redundant connections on the backbone network to allow high speed and the amount of bandwidth required to meet the needs of hundreds of cabinets. The network is then distributed through hubs, switches, firewalls and gateways usually owned by the provider with fiber optic technology, to the exclusion of connection to the customer that can be done through an ethernet cable.
Plant Safety
Webfarm contains a capital of servers and equipment immense, so the access to the rooms is very limited and are fastened by means of a badge or biometric recognition. The farm is guarded 24 hours by 24 guards (in some webfarm is allowed access to the rooms 24 hours out of 24) which are helped by a very large number of cameras.