CDCS Practice Questions

The cooling capacity of a raised floor tile is primarily influenced by the percentage of surface

opening, the obstruction caused by the supporting construction, the pressure under the raised floor,

and the damper construction. These factors dictate how much airflow can pass through the tile and

how effectively cool air is distributed to the equipment in the data center.

Detailed Explanation:

The percentage of surface opening on a floor tile affects how much air can flow through, with larger

openings allowing more airflow. Supporting structures beneath the floor can obstruct airflow,

reducing cooling efficiency. Pressure under the raised floor impacts the velocity and volume of air

that moves through the tile. Additionally, if dampers are installed, they control the airflow rate,

which can be adjusted to meet specific cooling needs for the area.

EPI Data Center Specialist Reference:

EPI guidance on airflow management under raised floors emphasizes these factors as critical for

effective cooling, especially in high-density areas. Ensuring unobstructed and adequate airflow helps

maintain consistent cooling across equipment.

A hypoxic-based fire suppression system works by reducing the oxygen level in a room to below what

is necessary to sustain combustion. This makes it effective in fire prevention, but it is not suitable for

continuous occupancy by personnel. Low oxygen levels can cause discomfort or even health risks for

people spending extended periods in the space. Therefore, these systems are typically deployed in

areas where continuous human occupancy is not required, such as storage rooms or data halls with

limited personnel access.

Detailed Explanation:

Hypoxic fire suppression systems lower oxygen levels to around 15-16%, which is safe for short

periods but not sustainable for continuous occupancy without risk to health. Data center

environments where staff need to spend long periods monitoring and maintaining equipment would

need alternative systems, like gas-based suppression that allows for safe evacuation rather than

oxygen reduction.

EPI Data Center Specialist Reference:

The EPI Data Center Specialist curriculum emphasizes that fire suppression systems must be chosen

based on occupancy requirements. Hypoxic systems are specifically noted as unsuitable for spaces

requiring continuous human presence due to the low oxygen environment they create.

In locations with consistently cold temperatures, such as above the Arctic Circle, an airside

economizer is the most energy-efficient cooling solution. Airside economizers use cool outside air to

lower indoor temperatures, reducing or even eliminating the need for mechanical cooling. Given the

consistently low temperatures, this method maximizes energy efficiency by leveraging natural

cooling.

Detailed Explanation:

Airside economizers are ideal in environments where outside temperatures are consistently low. By

drawing in and filtering cold outdoor air, they directly cool the indoor environment, thereby reducing

energy consumption significantly compared to traditional air conditioning. This cooling approach

aligns with energy efficiency goals by minimizing mechanical cooling demands.

EPI Data Center Specialist Reference:

EPI recommends the use of airside economizers in cold climates to achieve high energy efficiency, as

they allow data centers to capitalize on ambient conditions for cooling, aligning with sustainability

and cost-saving practices.

For heavy equipment, such as a network storage device weighing approximately 600 kg/1,300 lbs,

new floor loading calculations are indeed required, particularly since the rack is non-standard. A

structural engineer, approved by the building owner, should conduct these calculations to ensure the

floor can safely support the new load without risking structural integrity.

Detailed Explanation:

Data centers are designed with specific floor load ratings, which are determined during the design

phase based on anticipated equipment. When adding or replacing equipment that is significantly

heavy or non-standard, reassessing the floor's capacity is essential to avoid overloading. A structural

engineer has the expertise to verify if the existing floor can accommodate the weight and, if not, can

recommend reinforcement measures.

This step ensures compliance with safety standards and helps prevent damage to the infrastructure,

which could lead to costly repairs or even catastrophic failure in extreme cases.

EPI Data Center Specialist Reference:

EPI Data Center Specialist training advises that any changes in the data center load, particularly

involving non-standard and heavy equipment, warrant a structural assessment. Ensuring compliance

with floor load capacity is a critical safety and operational concern, as underscoring data center

infrastructure reliability and safety is a priority in EPI's best practices.

A spirit level bar should not be used for leveling a raised floor, as measurement errors are likely to

propagate from one pedestal to the next. Spirit levels can introduce cumulative errors, leading to

uneven floors, particularly in large installations where precise leveling is critical.

Detailed Explanation:

Using a laser level or a precision leveling device is recommended to ensure accuracy across all floor

tiles. Spirit levels, while adequate for short spans, can transfer small inaccuracies from one pedestal

to another, which can cause alignment issues and floor instability over time.

EPI Data Center Specialist Reference:

EPI data center guidelines discourage the use of spirit levels for raised floors. Instead, they advocate

for precision tools like laser levels that ensure consistency and accuracy in large-scale installations,

aligning with best practices for raised floor construction.

High levels of H2S (hydrogen sulfide) gas contamination in a computer room are best addressed by

installing air-scrubbers. Air-scrubbers can effectively filter out contaminants, including corrosive

gases like H2S, ensuring clean air circulation and protecting sensitive IT equipment from potential

corrosion and damage.

Detailed Explanation:

Air-scrubbers are designed to remove various airborne contaminants and are particularly useful in

environments where corrosive gases are present. These systems use filters or chemical reactions to

neutralize harmful substances, making them ideal for data centers that need to maintain high air

quality for equipment reliability.

EPI Data Center Specialist Reference:

EPI guidelines suggest air-scrubbing technologies to remove contaminants that pose risks to

electronic equipment, maintaining air quality and reducing corrosion risk.

An air intake temperature of 25 °C (77 °F) at the top of the rack is acceptable according to data center

standards and guidelines, such as those from ASHRAE. This temperature falls within the

recommended range for inlet temperatures, which is typically between 18°C (64°F) and 27°C (81°F).

Detailed Explanation:

ASHRAE standards provide guidelines on acceptable temperature ranges for air intake in data centers

to balance cooling efficiency and equipment safety. A temperature of 25°C is within the

recommended operational range, allowing data centers to optimize energy efficiency while

maintaining safe conditions for IT equipment.

EPI Data Center Specialist Reference:

EPI guidelines align with ASHRAE recommendations for server intake temperatures, confirming that

25°C is within acceptable limits for most mission-critical equipment. This ensures the data center

maintains an efficient and reliable environment.

When installing a raised floor, the best starting point is typically from the farthest corner away from

the entrance, in this case, Point B. This method allows for the floor installation to progress towards

the entrance, ensuring that workers can avoid walking over the newly installed tiles, thus minimizing

the risk of damage and maintaining cleanliness during installation.

Detailed Explanation:

Starting at the farthest corner (Point B) and working towards the entrance (Point A) is a standard

practice in raised floor installation. This approach ensures that installers do not walk over freshly laid

tiles, which could lead to shifting or misalignment. Additionally, it allows for more controlled

placement and alignment, as well as convenient egress when installation is complete.

EPI Data Center Specialist Reference:

EPI guidelines for raised floor installation emphasize beginning at the farthest point from the

entrance and working back towards it, which aligns with industry best practices for efficiency and

quality assurance. This method reduces potential damage and supports precise alignment across the

floor area.

In areas with frequent and extended power outages, continuous generators with at least an N+1

configuration are necessary to ensure consistent power availability. Continuous generators are

designed for prolonged operation, making them suitable for scenarios where utility power is

frequently unavailable, as in this case with outages exceeding 650 hours per year. An N+1

configuration ensures redundancy, which is critical for maintaining uptime in a high-availability data

center.

Detailed Explanation:

Continuous generators provide reliable power over long durations, unlike standby generators, which

are intended only for short-term use. The N+1 configuration ensures that there is always an

additional generator available in case of failure, thus maintaining power supply even if one generator

goes offline.

EPI Data Center Specialist Reference:

EPI best practices recommend continuous generators with redundancy for data centers located in

areas with high power instability to maintain reliability and continuous operation.

The minimum requirement for power feeds to a Rated-3 data center according to ANSI/TIA-942 is to

have two independent power feeds, which can come from two different substations provided by the

same power company. This ensures redundancy and concurrent maintainability, as each feed can

support the load independently during maintenance or failure of the other.

Detailed Explanation:

The separation by two substations ensures resilience in case of a localized outage or substation

maintenance, aligning with Rated-3 requirements for uninterrupted operation. ANSI/TIA-942 permits

these feeds from a single utility provider as long as they are supplied from distinct substations.

EPI Data Center Specialist Reference:

EPI underscores the importance of dual power feeds from separate substations for Rated-3 facilities,

highlighting that the ability to draw from different substations aligns with redundancy requirements

for high availability.