Description of a typical data center

• Computer surfaces: eight computer rooms of about 250 m²each, about 2000 m²of net data surfaces spread over two floors

• Office surfaces: 425 m²

• Storage surfaces: 225 m²

• Various premises reserved for infrastructures (electricity, air conditioning, etc.)

• Parking lots

• Storage rooms

• Meeting / Integration Rooms

• 2 MMR (Meet Me Room)

• Delivery zone

• Delivery: heavy assets elevator adapted to the needs

• Suitable traffic (width, slope and allowable loads)

Figure 3.6: Typical design of a data center. Blocks A and B are totally independent electrically and mechanically.

DATA4’s data centers can be qualified as of the last generation. The company offers a continuity of services, as close as possible to the Tier III + definition.

The architecture is designed with a double general A + B power supply chain, including the power supply for the air-conditioning systems. The building and the infrastructures of critical systems exist since 2012, and guarantee the durability and the continuity of the services over time.

3.3 DATA4 Group’s Data Center Overview

Table 3.1: Summary of the DATA4 data center’s technical specifications.The items listed in the table describe the technical specifications of the production site and the back-up site

No incidents have been reported since the creation of the campus.

DATA4 allows to obtain a complete traceability of the overall events.

The data centers’ design is based on the principle of maintainability (or the ability for components or applications to be maintained, consistently and affordable, in the good functioning order) without impact. This means that all the distribution paths, for electrical power and air conditioning, are simultaneously maintainable without impacting customer operations.

Electrical system

High voltage electrical connection 90 kV

The DATA4 data center campus benefits from a unique location: located less than 5 km from the largest electricity distribution station in France, Villejust, which allows it to rise in power.

The campus is powered by two private high-voltage direct power lines of 90 kV. Both are active simultaneously and allow each other to develop the overall power.

DATA4 has transformer rooms on campus to lower down the voltage from 90 kV (provided by ERDF) to 20 kV. The transformation from 90 kV to 20 kV is performed by two transformers of 40 MVA each. The electrical capacity of the site is 100 MW.

This loop participates in major French inter-regional energy exchanges. From these substations, there are 225 kV lines which bring power to the substations located in the greater or the nearest suburbs and are intended to feed the local power supplies.

The distribution for each building is done by four 20 kV lines feeding four transformers (two per block, two blocks per building). The emergency site is powered by two 20 kV supplies (ERDF).

Electrical distribution in the data center

The power supply of a building is backed up by generators with an autonomy of 72 hours at full load.

The generators are tested in real time every month. DATA4 has a fuel supply contract with TOTAL.

Two independent power supply chains, operated by the data center, allow the maintenance of the electrical installations, without stopping the computer operations, as such it is transparent for the customer. The racks function with dual electrical feeding (two uninterruptible supply sources). The autonomy of these supply sources is at least 20 min when fully loaded.

Air conditioning system General principle

DATA4 uses an indirect chilled water cooling system. The production of the cooling is in N + 1 configuration. Chilled water is produced by refrigeration units with high energy efficiency. Each building has a cooling capacity of 4 MW upgradeable to 6 MW, according to the customers’ needs.

The refrigerating units are redundant N + 1. Two separate chilled water networks provide power to the cooling terminals associated with the computer rooms. The heat exchange (water / air) takes place in the technical corridors through the recycling equipment. The hot air is sucked in by six N + 2 redundant air recycling equipment. They process the room’s atmosphere independently by regulating the recovery temperature. The use of variable speed fans improves energy efficiency and helps improve the Power Usage Effectiveness (PUE).

Definition 29 The Power Usage Effectiveness (PUE) is used to measure the energy efficiency of an IT operations center. It corresponds to the ratio between the total energy consumed, by the entire operating center (with air conditioning), and the part, which is actually consumed by the computer systems (servers, storage, network). The ideal PUE tends to 1,0 but still remains a little higher than this value because there are other electrical equipment, other than the computer

3.3 DATA4 Group’s Data Center Overview

Table 3.2: Specifics of the electrical system

servers, deployed in a center and therefore, the ratio to the energy, which it consumes will always be higher than 1. For example, Google has noticed that the PUE in its data centres go from 1,20 in 2009 to 1,12 in 2014^a.

a Google data centers, Efficiency: How we do it.

Particularity of the DATA4 air conditioning

DATA4 has developed a unique air conditioning process, with fresh air blowing through an adjustable diffusing ceiling. There is no false floor. This system allows a permanent control of the technical installations, thanks to a separate aerial installation of all the networks: high voltage, low voltage, optical fiber networks. It improves the reliability of the installation: the facilities are visible, easier to implement and allow the IT hosting surfaces’ operations, to take place, in optimal conditions.

This process is the subject of two patents and can reduce from 20% to 30% the power consumption of the air-conditioning room’s systems, compared to a cooling system by blowing from the false floor. Thanks to this powerful air conditioning system and controlled management of the building’s operations, DATA4 is now positioned with one of the best energy performances.

• Temperature

The air-conditioning is sized according to the installed electrical power. The specific indoor temperature conditions are regulated by six climate control cabinets dedicated to each room.

The set of temperatures is set at 21^oC (±3^oC) and adaptable to the needs of the user. The DATA4’s commitment is made, on the average temperature of recovery of the room. This temperature is maintained, regardless of the external climatic conditions, regardless of the overall load dissipated by the IT and telecom equipment, and within the limits of the contracted power. Air-conditioning maintenance is performed without affecting the weather conditions in the computer rooms.

• Hygrometry

DATA4’s commitment concerns the overall hygrometry conditions of the room. Indoor

Figure 3.7: Elements of the Air-conditioning system

hygrometry is between 30% and 70%. These hygrometry conditions are maintained whatever the external climatic conditions, the overall load dissipated by the customer’s equipment, within the limit of the contracted power. The sensors which control the hygrometry are located in the air treatment plant (ATP), dedicated to the computer rooms.

• Air quality

The air is treated by two ATPs, one in totally secured by the other, with advanced filtration F7 (fine filter, more than 35% efficiency to 0.4 micron). An air humidification system is put into place. The air is maintained continuously at a slight over pressure, in the computer room, in order to limit the risk of the waste air transmission from other premises to the computer rooms (air pollution, smoke, etc.).

The air processing units operate in optimum performance with maximum longevity. On the other hand, the ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engineers) recommends increasing the range of regulation. DATA4 has opted for global temperature and hygrometry, relying upon a partial technical obstruction, rather than a complete containment. The major advantage for the Customer lies upon the optimal flexibility of the urbanization of its hosting space, avoiding partitioning, thanks to the flexibility of the use of facilities (width of aisles and height available).

The implementation of the room’s homogeneity service allows:

• Analysis of hot spots and air flows;

• Improvement of the thermal homogeneity in the room;

• The reduction of thermal impacts in the room in case of an air-conditioning incident;

• The realization of common actions;

• Control of all the infrastructures;

• Proactive risk actions, in case of breakdowns and provide remedial proposals;

• Back up choices for moving equipment;

• Infrastructure’s budget control for development needs.