Data Centres: What they are (and what they are not) – Part II
A short educational series focused on the physical infrastructure of Data Centers, designed to clarify concepts and separate facts from interpretations.
In the previous article, we saw that a Data Center is fundamentally a real estate and infrastructure investment: a facility built or adapted to host computers.
Continuing with the hotel analogy, a Data Center must do more than simply provide space for its guests (computers and other IT equipment). It must also ensure a range of supporting services, including:
- Power supply
- Cooling and environmental control
- Security
- Communications
- Cleaning
- Technical and logistical support
In this article, I will focus on the physical accommodation of computers and other IT equipment. Future articles will explore the infrastructure that supports the services listed above.
In a Data Center, equipment is installed inside dedicated cabinets, commonly referred to as racks. These racks are placed inside rooms or halls.
A Data Center may consist of several buildings (or modules). Each module may contain multiple rooms, each room may contain dozens or even hundreds of racks, and each rack may house dozens of devices such as servers, storage systems or firewalls.
Typically, racks are positioned side by side in rows, and the rows are separated by open spaces known as aisles. These aisles may serve as pathways for technicians or as channels for airflow and cooling. Data Center cooling is, in itself, a broad topic that we will cover in a future publication.
The most common racks are approximately 60 cm wide, 190 cm high and 80 cm deep, although other standard dimensions exist. Today, most IT equipment is manufactured according to standard sizes so that it can be installed inside a rack much like drawers in a cabinet.
The available vertical space inside a rack is usually measured in rack units (U). Each U corresponds to 1.75 inches (approximately 44.45 mm), and the most common racks provide 42 U of usable height. As a result, equipment size is often expressed in rack units.
Equipment may require 1, 2, 3 or more U depending on its dimensions and other factors, the most important being cooling requirements. In practice, equipment density inside a rack must take heat dissipation into account, which sometimes requires leaving empty rack units to improve airflow.
At the rear of the equipment, there is typically free space within the rack for power cables, network connections and interconnection cabling.
Racks generally include lockable doors, which may use physical keys, access codes or biometric authentication to restrict access to authorized personnel. These doors are often fitted with mesh panels, although glass panels may also be used depending on the cooling method employed.
For reasons of standardization and space management, racks are usually provided by the Data Center operator. In some cases, however, customers may use their own racks.
Any organization may choose to host its hardware infrastructure in a Data Center. This decision is influenced by many factors, including the cost of building and maintaining an internal technical facility, the need for uninterrupted power supply, data centre security certifications, connectivity to business partners using the same facility, and more.
Today, the two main factors that determine hosting costs in a Data Center are:
- The physical space required by the equipment;
- Power requirements (capacity and consumption).
The need to optimize space means that equipment belonging to different organizations is often hosted within the same row of racks, or even within the same rack. In shared-rack environments, separate compartments or access doors ensure that each customer can only access its own equipment.
Most Data Centers offer hosting options such as:
- Half rack (20 or 21 U)
- Quarter rack (10 or 11 U)
For organizations with higher security requirements, exclusive areas can also be contracted, ranging from isolated sections within a room to an entire room dedicated to a single customer.
An isolated area is typically enclosed by metal mesh walls and is commonly referred to as a cage. The cage includes a lockable door to ensure that only authorized personnel can access the equipment. In most cases, the installation of these cages is managed by the Data Center operator.
In the next article, we will discuss the other major pricing factor: electrical power and consumption.
So now you know:
- A data center → contains multiple rooms
- A room → contains dozens or hundreds of racks
- A rack → can host dozens of IT devices
- Who can use a data center? → any organization wishing to host IT equipment
- Hosting costs → depend mainly on space requirements and power consumption, usually with minimum service tiers
By Paulo Simões, Founder of Cloud365