Certified Data Centre Professional (CDCP)

A design consideration that should be implemented with an Inergen-based fire suppression system is to install pressure relief valves in the room that needs protection. Inergen is a clean agent fire suppression system that uses a mixture of inert gases (nitrogen, argon, and carbon dioxide) to displace the oxygen in the room and extinguish the fire. However, when Inergen is released into the room, it creates a sudden increase in pressure, which can damage the walls, doors, windows, and ceilings of the room. To prevent this, pressure relief valves are required to vent the excess pressure to the outside and maintain a safe pressure level inside the room. Pressure relief valves should be designed and installed in accordance with the relevant standards and codes, such as NFPA 2001 and ISO 14520.

The primary reason to install a monitoring system in the data centre is to notice abnormalities early so that actions can be taken to avoid disasters, according to the CDCP Preparation Guide1 and various web sources 234. A monitoring system is a system that collects and analyzes data about the power, cooling, environmental, and security conditions in the data centre, and alerts the operators or managers about any issues or threats that may affect the performance, availability, or reliability of the data centre. A monitoring system can help to prevent or minimize the impact of disasters, such as power outages, fire, water damage, overheating, equipment failure, or cyberattacks, by providing timely and accurate information that enables fast and corrective action. A monitoring system can also help to improve the energy efficiency, capacity planning, and asset management of the data centre, by providing useful insights and trends that
support informed decision making.

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.

References:
CDCP Exam Preparation Guide, Environmental Controls

Combining operational evidence helps management identify recurring weaknesses and direct improvement work where it has the greatest value. Waiting for major failure or hiding lessons prevents systematic improvement.

According to the CDCP?Preparation Guide, smoke detectors are the most common type of fire detection devices used in data centers, as they can detect a fire in its early stages and provide early warning to the occupants and authorities. Smoke detectors can be either spot-type or air-aspirating, depending on the design and goals of the data center. Spot-type detectors are inexpensive and simple, but may cause activation delay and false alarms. Air-aspirating detectors are more sensitive and reliable, but may require more maintenance and installation costs. Both types of detectors should be installed in accordance with the relevant standards and codes, such as NFPA 72 and EN 54.

According to the IBM document on temperature and humidity design criteria, the temperature and humidity values indicated on the display of the computer room air conditioner unit are the values measured at the intake of the air conditioner. This is because the intake is where the air conditioner draws the air from the computer room and cools and dehumidifies it before sending it back to the computer room. The display shows the current conditions of the computer room air, which are used to adjust the cooling and dehumidifying operations of the air conditioner. The values measured at the exhaust (outlet) of the air conditioner are not displayed, as they are not relevant for the computer room environment. The values measured at the front of the rack of the aisle the air conditioner is situated are also not displayed, as they may vary depending on the distance and location of the rack. The average value between the intake and exhaust (outlet) of the air conditioner is not displayed, as it does not reflect the actual conditions of the computer room air or the air conditioner performance.

References:
Temperature and humidity design criteria - IBM

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.

8760 is the number of hours in a year (24 hours x 365 days). Dividing annual revenue by 8760 gives a basic average revenue per hour, commonly used in downtime cost calculations.

References:
CDCP Exam Preparation Guide, page 34
EPI Data Centre Professional Course Materials

According to the EPI Data Centre Professional (CDCP? Preparation Guide, Class K fires involve cooking appliances that use combustible cooking media such as vegetable or animal oils and fats (page 28). Class K fires require special extinguishing agents that can suppress the high-temperature flames and prevent re-ignition. Class K fires are different from Class B fires, which involve flammable liquids such as gasoline, oil, or paint.

Physical separation is the most cost-effective method to minimize electromagnetic interference. Specialized shielding is more expensive and usually unnecessary if proper separation is maintained.

References:
CDCP Exam Preparation Guide, EMF Section