Have you ever wondered where the photos and videos we save online end up? Obviously they don’t remain suspended in the air: there are physical places, buildings, where all the files we consult online are stored. These places are data centers. And they are not just used to store information: every time we give a command to a website, from social networks to streaming platforms, the data centers carry out these operations.
How data centers are made
If we wanted to specifically analyze how a data center is made, we could summarize everything in three main functions.
1. Calculation
This word refers to the capacity of data centers to process data, expressed in terms of power. A bit like the CPU of our computer, which tells us how fast it is at doing things, but on a much, much larger scale. In fact, data centers must have many computers with large computing capacities, because many websites rely on them. Think of banks or public administrations, but also of social networks or streaming services. All these sites, which we access online, have their own computing structure within data centers.
However, we must not imagine a single gigantic computer that works alone for everyone. This function is in fact divided between many small computers, the servers, which share the same supporting structure and the same cooling system. The most common servers are like pizza boxes: many flattened rectangles, arranged one on top of the other inside a structure called a rack. Rack servers are certainly the most widespread, but there is also another type, blade servers, which unlike racks are thinner and inserted inside a frame. In this way the blade servers share not only cooling, but also power and cabling, making everything even more compact.
2. Storage
This term refers to the capacity of data centers to accumulate and store information, physically represented by memory disks. We are not just referring to the photos and videos of our holidays: each site, platform or app brings with it a package of information to draw on every time, and this information also finds a place within the data centers. We speak of DAS (Direct-Attached Storage) if the information is physically connected to its reference server, while we speak of NAS (Network-Attached Storage) if it is connected to the server via an Ethernet connection. There is then a further evolution of these two systems represented by the SAN (Storage Area Network) which allows servers to draw on this information not for individual files but for blocks (as in the example of large databases) via more modern fiber connections.
3. Network
This word refers to that gigantic set of cables, switches, routers and firewalls that connect servers and storage disks to each other, and which, at the same time, connects both with the outside world. In these cases we talk about east-west traffic for internal connections, and north-south traffic for those to and from the outside.
How you keep data centers running
When we talk about electrical power supply, the key concept is that of “redundancy”, which says that there must always be at least one extra power supply channel, disconnected from the others, ready to take over if necessary. To ensure this, most common data centers are equipped with diesel or gas backup generators, or large battery systems. Another fundamental thing is to avoid overheating the servers, since all this electricity inevitably generates heat. To solve this, data centers are usually designed to channel the flows of air conditioning along corridors, called “cold corridors”, which are overlooked by the side of the rack designed to suck in the air. On the back, however, or on the side where the rack expels the air, the so-called “hot corridors” are created. The expelled hot air is then generally converted back into cold air, using special air conditioners that use chilled water, but it could also be recycled towards the outside: an example is the Avalon 3 data center in Milan, whose waste heat will be used to heat around 1,600 homes in the Milan area. The last important condition for the operation of data centers is related to security. Since the functioning of essential services depends on them, data centers must also be protected against attempts at damage and hacking. For this reason they are structures equipped with the most modern surveillance systems, both in terms of the security of the building itself and in terms of cybersecurity, through firewalls, data encryption and monitoring of suspicious activities.
How many data centers are there in Italy
You will have understood, at this point, that data centers are in all respects the nerve center of our economies. Without them, the physical infrastructure on which practically all digital services are based, which are fundamental for many of the actions we carry out every day, would disappear. But how many data centers do we have in Italy? As of November 2025, there were over 200 data centers in Italy, a constantly increasing number which positions us as the thirteenth nation in the world. An example is that of Retelit, an Italian company that boasts a network of 38 data centers spread across the peninsula. At the center of this infrastructure is the Avalon Campus in Milan, one of the most important interconnection points in the country: the majority of Italian internet traffic passes through its three buildings, Avalon 1, 2 and 3, with more than 170 national and international operators hosted within them. Retelit also plans to build 3 new generation data centers to meet the technological challenges of the near future, one above all that of artificial intelligence, which with its data processing demands is literally revolutionizing the data center sector.
