CDCP Data Center Cooling 2 — Questions and Answers
Question 1: What is the primary purpose of a hot aisle/cold aisle containment system in a data center?
- To reduce noise levels from server fans
- To separate hot exhaust air from cold supply air and improve cooling efficiency (Correct answer)
- To organize cable management between server racks
- To provide physical security separation between rack rows
Correct answer: To separate hot exhaust air from cold supply air and improve cooling efficiency
Hot aisle/cold aisle containment physically separates the hot exhaust air from servers from the cold supply air, preventing mixing and dramatically improving cooling efficiency.
Question 2: Which cooling metric measures the efficiency of a data center's cooling infrastructure by comparing total facility power to IT equipment power?
- COP (Coefficient of Performance)
- PUE (Power Usage Effectiveness) (Correct answer)
- DCiE (Data Center Infrastructure Efficiency)
- ERE (Energy Reuse Effectiveness)
Correct answer: PUE (Power Usage Effectiveness)
PUE is calculated as total facility power divided by IT equipment power; a PUE of 1.0 is perfect, meaning all power goes to IT equipment with no overhead.
Question 3: In a data center cooling system, what does CRAC stand for?
- Cooling Room Air Conditioner
- Computer Room Air Conditioner (Correct answer)
- Central Rack Air Controller
- Chilled Rack Air Circulation
Correct answer: Computer Room Air Conditioner
CRAC (Computer Room Air Conditioner) is a precision cooling unit designed specifically for data center environments, unlike standard HVAC units.
Question 4: What is the recommended ASHRAE temperature range for Class A1 IT equipment inlet air?
- 50°F to 77°F (10°C to 25°C)
- 59°F to 89.6°F (15°C to 32°C)
- 64.4°F to 80.6°F (18°C to 27°C) (Correct answer)
- 41°F to 95°F (5°C to 35°C)
Correct answer: 64.4°F to 80.6°F (18°C to 27°C)
ASHRAE A1 class equipment specifies an inlet air temperature range of 59–77°F (15–27°C) with the recommended range being 64.4–80.6°F (18–27°C).
Question 5: Which type of economizer uses outdoor air directly to cool the data center without mechanical refrigeration when conditions permit?
- Water-side economizer
- Air-side economizer (Correct answer)
- Evaporative economizer
- Mechanical economizer
Correct answer: Air-side economizer
An air-side economizer brings outdoor air directly into the data center for cooling when ambient temperatures and humidity are within acceptable limits, eliminating chiller operation.
Question 6: What is the function of perforated floor tiles in a raised floor data center cooling design?
- To support heavy equipment loads while allowing drainage
- To distribute cold supply air from the underfloor plenum to the cold aisle (Correct answer)
- To reduce static electricity buildup on the data center floor
- To provide cable routing pathways between racks
Correct answer: To distribute cold supply air from the underfloor plenum to the cold aisle
Perforated floor tiles allow cold air from the pressurized underfloor plenum to rise into the cold aisle where IT equipment intakes are located.
Question 7: What is 'free cooling' in the context of data center thermal management?
- Using waste heat from servers to heat office spaces at no cost
- Leveraging ambient environmental conditions to cool the facility without or with minimal mechanical refrigeration (Correct answer)
- Eliminating all cooling costs through server virtualization
- Using solar panels to power cooling systems for zero energy cost
Correct answer: Leveraging ambient environmental conditions to cool the facility without or with minimal mechanical refrigeration
Free cooling uses naturally cool ambient air or water temperatures to reduce or eliminate compressor-based cooling, significantly cutting energy costs during favorable weather.
CDCP Data Center Cooling 2
What is the primary purpose of a hot aisle/cold aisle containment system in a data center?