CDCP Certified Data Centre Professional (CDCP) Questions and Answers

Waveform distortion is a type of AC power quality anomaly that occurs when the shape of the voltage or current waveform deviates from the ideal sinusoidal shape. Waveform distortion can be caused by nonlinear loads, such as rectifiers, inverters, variable frequency drives, and electronic devices, that draw current in pulses or harmonics. Waveform distortion can result in overheating, reduced efficiency, malfunctioning, or damage of equipment.

Hot- or cold-aisle containment is a strategy to improve the cooling efficiency and reduce the energy consumption of data centers by isolating the hot exhaust air from the cold supply air. However, implementing this strategy in an existing computer room may create potential issues with the existing fire suppression system(s), such as:

•The containment barriers may interfere with the distribution and activation of the fire suppression agents, such as water, gas, or aerosol, and reduce their effectiveness in extinguishing a fire.

•The containment barriers may create pockets of high temperature and pressure that could damage the equipment or the containment structure itself in the event of a fire.

•The containment barriers may obstruct the access and visibility of the fire detection and alarm devices, such as smoke detectors, heat sensors, or manual call points, and delay the response time of the fire suppression system(s).

•The containment barriers may violate the local fire codes and regulations that specify the minimum clearance and ventilation requirements for the data center.

Therefore, when implementing hot- or cold-aisle containment in an existing computer room, it is important to consider the impact on the existing fire suppression system(s) and take appropriate measures to ensure the safety and compliance of the data center, such as:

•Consulting with the fire authorities and the fire suppression system vendor to assess the compatibility and suitability of the containment solution with the existing fire suppression system(s).

•Modifying or upgrading the existing fire suppression system(s) to accommodate the containment solution, such as relocating or adding fire suppression devices, adjusting the discharge rate and pressure, or installing a secondary fire suppression system within the contained area.

•Installing fire-rated containment barriers that can withstand high temperatures and resist the spread of fire and smoke, and that have self-closing or automatic release mechanisms in case of a fire.

•Installing fire detection and alarm devices within the contained area and ensuring their proper integration and communication with the existing fire suppression system(s).

•Conducting regular testing and maintenance of the fire suppression system(s) and the containment solution to ensure their functionality and reliability.

Measuring business value is the process of assessing the benefits and costs of IT investments and initiatives in relation to the strategic objectives and priorities of the organization. One of the factors that can be used to measure business value is scalability, which is the ability of a system or component to handle increasing workloads or demands without compromising performance, quality, or functionality. Scalability is important for business value because it enables the organization to adapt to changing market conditions, customer expectations, and growth opportunities. Scalability can also reduce operational costs, increase efficiency, and improve customer satisfaction. Therefore, scalability is one of the factors that can be used in measuring business value.

High relative humidity in a data center can lead to corrosion of metal parts and electronic contacts, potentially causing failures. Electrostatic discharge is a risk with low humidity, not high.

According to the CDCP Preparation Guide1, risk can be defined as the product of impact and probability. Impact is the measure of the negative consequences or losses that may result from a risk event, such as downtime, data loss, or damage to the data centre. Probability is the measure of the likelihood or frequency of a risk event occurring, based on historical data, expert judgment, or statistical analysis. By multiplying impact and probability, risk can be quantified and compared, which helps in prioritizing and mitigating the risks. For example, a risk event that has a high impact but a low probability may have the same risk level as a risk event that has a low impact but a high probability.

When having two non-synchronized power sources, the ATS / STS need to be of the type break before make, which means that the switch disconnects from one source before connecting to the other source. This prevents any short circuit, back feed, or phase mismatch that could occur if the two sources were connected simultaneously. Break before make switches are also known as open transition switches, because they create a brief interruption in the power supply during the switching process. This interruption is usually acceptable for most ICT equipment, as they have internal power supplies or batteries that can handle the transient. However, if the interruption is not acceptable, then the two power sources need to be synchronized before switching, which requires a make before break switch, also known as a closed transition switch. Make before break switches connect to the second source before disconnecting from the first source, which ensures a seamless transfer of power without any interruption. However, make before break switches require that the two sources have the same voltage, frequency, and phase, which can be achieved by using a synchronization module or a phase-locked loop.

The most damaging type of floor load for raised floor tiles in a data centre is the rolling load (RL), according to the CDCP Preparation Guide1 and various web sources234. A rolling load is the load that is applied by a moving object, such as a pallet jack, a forklift, or a rack on wheels. A rolling load can cause more stress and fatigue on the raised floor tiles than a static load, such as a concentrated load (CP) or a uniformly distributed load (UDL), because it creates dynamic forces and impacts that can crack, dent, or deform the tiles. Moreover, a rolling load can also damage the pedestals and stringers that support the tiles, and cause the tiles to become loose or misaligned. Therefore, when designing and installing a raised floor system, it is important to consider the maximum rolling load that the tiles can withstand, and to use appropriate materials and methods to enhance the strength and durability of the tiles. For example, some possible solutions include using steel or concrete-filled tiles, reinforcing the edges and corners of the tiles, and using locking or gravity-held systems to secure the tiles.

A UPS (uninterruptible power supply) that is categorized as VFD class is not a fit for your mission-critical data centre, because it does not provide adequate protection against voltage and frequency variations. VFD stands for Voltage and Frequency Dependent, which means that the output voltage and frequency of the UPS depend on the input voltage and frequency. VFD UPSs are also known as offline, standby, or line-interactive UPSs. They typically switch to battery power only when the input power fails or goes beyond a certain threshold. However, this switching may cause a brief interruption or a transient in the output power, which can affect the performance and reliability of the ICT equipment. Moreover, VFD UPSs do not filter or regulate the input power, which means that they pass on any voltage or frequency fluctuations, harmonics, or noise to the output power. These power quality issues can also damage or degrade the ICT equipment and the data.

For your mission-critical data centre, you need a UPS that is categorized as VFI class, which stands for Voltage and Frequency Independent. VFI UPSs are also known as online, continuous, or double-conversion UPSs. They provide a constant and clean output power that is independent of the input power. VFI UPSs convert the input AC power to DC power, and then convert it back to AC power with the desired voltage and frequency. This double conversion process isolates the output power from the input power, and eliminates any power quality issues. VFI UPSs also have zero switching time, which means that they do not cause any interruption or transient in the output power when switching to battery power. VFI UPSs are designed to protect the ICT equipment and the data from any adverse effects of voltage and frequency variations, and to ensure the highest level of availability and reliability.

Fiber-optic cables use light as the source to transmit data. Light pulses are modulated to carry information through an optical fiber. The light is confined in the core of the fiber by total internal reflection at the core-cladding interface. The light travels along the fiber with minimal loss or interference, making it suitable for long-distance and high-bandwidth applications.

A service corridor is a dedicated space within or adjacent to a data centre that allows access to the supporting facilities, such as power, cooling, fire suppression, security, and cabling systems, without interfering with the computer room operations. A service corridor helps to isolate the noise, vibration, heat, and dust generated by the supporting facilities from the sensitive equipment in the computer room. A service corridor also enhances the safety and efficiency of the maintenance and monitoring activities, as well as the flexibility and scalability of the data centre design.

Legal fees are an example of direct cost because they can be directly attributed to a specific project, product, or service. Legal fees are incurred for the purpose of obtaining legal advice, drafting contracts, resolving disputes, or complying with regulations related to the core business activity. Legal fees are not general overhead expenses that are shared by multiple cost objects.

New equipment should be unpacked, tested, and configured in a dedicated staging room before being moved to the live data hall to prevent contamination and disruptions.

According to the EPI Data Centre Operations Standard (DCOS), exit/emergency signs should be located at every escape door and pathways leading to doors (arrows) to ensure a safe and quick evacuation in case of an emergency1. This is also consistent with the best practices for data centre emergency preparedness and response, which recommend having a clear and visible signage system for emergency exits23.

Cooling capacity is the measure of a cooling system’s ability to remove heat from a space. The most preferred unit of measure for cooling capacity is watt (W), which is the SI unit for power. Watt is defined as the amount of energy transferred or converted per unit time. One watt is equal to one joule of energy per second. Using watt as the unit of measure for cooling capacity allows for easy comparison and calculation of the cooling performance and efficiency of different cooling systems.

Other units of measure for cooling capacity are ton, BTU, and horsepower, but they are less common and less convenient than watt. Ton is a unit of measure that describes how much water at freezing temperature can be frozen in 24 hours, equivalent to 3.5 kW or 12,000 BTU/h. BTU (British Thermal Unit) is a unit of measure that describes the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit, equivalent to 0.293 W. Horsepower is a unit of measure that describes the rate at which work is done, equivalent to 746 W.

Data centre design and infrastructure standards can vary from country to country, depending on the local regulations, codes, and practices. Therefore, it is important to check the local standards before designing, building, or operating a data centre in a specific location. Compliance to only international standards may not be sufficient or adequate to meet the local requirements, which could result in legal, financial, or operational risks. For example, some countries may have stricter fire safety, environmental, or energy efficiency standards than the international ones. Some countries may also have different electrical standards, such as voltage, frequency, or plug types. By checking the local standards, you can ensure that your data centre is compliant, safe, and efficient in the local context.

The objective of data center fire protection is to suppress or extinguish a fire before it can cause significant damage to the equipment, personnel, or business continuity. Fire suppression systems are designed to reduce the heat, oxygen, or fuel elements of the fire triangle, and to limit the spread of fire and smoke. Fire suppression systems can be classified into two types: water-based and gas-based. Water-based systems include sprinklers, mist, and water spray systems, which use water as the extinguishing agent. Gas-based systems include inert gas, halocarbon, and clean agent systems, which use gases or chemicals as the extinguishing agent. The choice of fire suppression system depends on several factors, such as the fire risk, the type of fuel, the environmental impact, the reliability, the cost, and the compatibility with the data center equipment and operations.

Escape route signage should be placed at every door providing a pathway to the exit or the assembly area, according to the CDCP Preparation Guide1 and the EU Safety/Health Signs Directive2. Escape route signage is used to guide the occupants of the data centre from wherever they are in the building, via a place of relative safety (the escape route), to the place of ultimate safety (the assembly area). Escape route signage should not be limited to only emergency escape doors or the main entrance of the data centre building, as these may not be accessible or visible from all locations. Escape route signage should also not include doors that do not lead to the exit or the assembly area, such as riser doors, doors of storage closets, or doors of other rooms, as these may confuse or mislead the occupants. Escape route signage should be placed at every door that provides a pathway to the exit or the assembly area, and should indicate the direction and distance of the escape route using pictograms, arrows, and words. Escape route signage should also be designed and installed in accordance with the relevant standards and codes, such as BS 5499 and ISO 7010.

Patch cables of a lower class than the structured cabling can degrade the overall link performance, so it is best practice to use the same or higher class.

Damaged brand perception is an example of an indirect cost because it is not directly related to a specific product or service, but rather to the overall reputation and image of the company. Damaged brand perception can result from various factors, such as poor quality, customer dissatisfaction, security breaches, or negative publicity. Damaged brand perception can affect the company’s ability to attract and retain customers, partners, and investors, and thus reduce its profitability and competitiveness.

Class C fires involve energized electrical equipment, such as computers, servers, switches, cables, and wiring. These fires require the use of non-conductive extinguishing agents, such as carbon dioxide, dry chemical, or clean agent, to prevent electrical shock and damage to the equipment. Water-based extinguishers, such as Class A or K, are not suitable for Class C fires, as water can conduct electricity and cause electrocution or short circuits.

Class D fires involve combustible metals or combustible metal alloys such as magnesium, sodium and potassium. These metals can react violently with water, air, or other chemicals, and require special extinguishing agents1