Data Center Fundamentals

Google Data Center, Council Bluffs Iowa
Google Data Center, Council Bluffs Iowa

Data centers are centralized hubs for storing, processing, and disseminating large volumes of data and applications for businesses.

In the modern age of information technology, the data center has become an essential part of government, education, and business enterprise. Responsible for storing the most critical and proprietary digital assets, there is no question that data centers play a vital role in our society.

Data centers across the world each contain thousands of servers that run non-stop around the clock. In 2013, the U.S. Department of Energy reported that data centers consumed about 100 billion kilowatt-hours of electricity, 1 representing more than 2% of all U.S. electricity use.

Large corporations and government institutions typically build and manage their own data center in-house if they have the resources, while others may rent space from a provider. Data centers at this scale may be the size of entire city blocks and be equipped with enough electrical infrastructure to power an entire town.

Spaces within data center

Segments within the data center serve unique purposes and are managed differently. These spaces must work together and depend on one another to collect, store, process and distribute data.

White space in data centers is the space allocated for IT equipment or the area where computer equipment is placed. It includes servers, storage, network gear, racks, air conditioning units, power distribution systems.

Gray space in data centers is the area where back-end equipment is located. This includes switch gear, UPS, transformers, chillers and generators. Because the primary function of the gray floor is to support white space area and the more white space required, more back-end structures to support.

The gray space may also contain a meet-me room (MMR), which is a managed space that allows cable companies, internet service providers (ISPs), other carriers to cross connect with data center tenants. The cross connects enter the white space and support the physical connections of different companies and ISPs within the same building, allowing them to exchange data before distributing services to the facility and owner’s internal network.

Raised Floor Systems

Raised floor systems provide containment for cabling and fresh cool intake air.
Raised floor systems provide containment for cabling and fresh cool intake air.

The white space design in the data center can be either raised floor or hard floor (solid floor). The raised design was intended to provide the space needed for cooling and cabling for power, with easy access to all elements. The proper placement of air returns and use of perforated floor tiles and sensors can help eliminate hot spots and gain efficiencies in the room.

Hot/Cold Aisles

Maintaining optimal cooling for servers is achieved by arranging equipment so that intake and exhaust air is directed into separate “hot/cold” aisles. In this configuration, the servers only receive fresh cold air and hot/cold air mixing between servers is greatly reduced compared to older methods.

Air is routed more efficiently and result in a greater temperature co-efficient across air-conditioning equipment, which also increases efficiency of the unit. Inefficiencies can exist through air leaks in the floor tiles, allowing cold air to enter the hot aisle.

Outlets close to a computer room A/C unit can force cold air back into the machine, reducing efficiency. Gaps between servers can allow air re-circulation within the rack. Blanking plates can be used to reduce this.

Server racks with and without cold aisle containment.

Balanced airflow is critically important in this configuration. More cold air than needed will flow over and mix with the discharge. Insufficient cold air will allow hot air to recirculate back into the cold aisle. Any imbalance will result in reduced efficiency.

Physical barriers separating the two air streams is a popular design. There are two basic methods:

  • Cold air containment is easy to implement, making it a good choice for existing centers. Only the intake portions of the server racks are enclosed. One disadvantage is any equipment outside the containment zone will only receive hot air.
  • Hot aisle containment is more suitable for new builds because it is more expensive to install. Cold air fills the room and hot discharge air is pushed into a void within the ceiling. This system offers the most efficiency and allows for a brief buffer in the event cooling systems fail.

Emergency Power Off Switch

The emergency power off switch is a safety measure for quickly disconnecting electrical power to a particular piece of equipment, or to an entire facility, in the event of an emergency. The EPO instantly shuts off all power in the data center room. Unintentional EPO activation is a leading cause of data center downtime.

Fire Protection

The two most commonly recognized smoke detection technologies are ionization smoke detection and photoelectric smoke detection.

Photoelectric-type alarms aim a light source into a sensing chamber at an angle away from the sensor. Smoke enters the chamber, reflecting light onto the light sensor; triggering the alarm.

Ionization-type smoke alarms have a small amount of radioactive material between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm.

Dual Sensor – these detectors use both photoelectric and ionization type.

Air Quality

CO2 sensors detect high concentration levels in a confined or poorly ventilated environment can cause harmful reactions in people. It is measured using “parts per million” (ppm) and typically has a presence of around 400 ppm. HVAC systems can monitor CO2 and adjust the amount of outside air entering the building to compensate.