Heating, ventilation, and air conditioning (HVAC) system is an important topic for the Security+ exam. If you’re planning on taking the exam, you should have a good understanding of HVAC systems. For example, can you answer this question?
Q. Your organization is evaluating replacement HVAC systems and is considering increasing current capacities. Which of the following is a potential security benefit of increasing the HVAC capabilities?
A. Lower MTBF times of hardware components due to lower temperatures
B. Higher MTBF times of hardware components due to lower temperatures
C. Lower MTTR times of hardware components due to lower temperatures
D. Higher MTTR times of hardware components due to lower temperatures
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.
Importance of HVAC Systems
Heating, ventilation, and air conditioning (HVAC) systems are important physical security controls that enhance the availability of systems. Quite simply, computers and other electronic equipment can’t handle drastic changes in temperatures, especially hot temperatures. If systems overheat, the chips can actually burn themselves out.
The cooling capacity of HVAC systems is measured as tonnage. This has nothing to do with weight, but instead refers to cooling capacity. One ton of cooling equals 12,000 British thermal units per hour (Btu/hour), and typical home HVAC systems are three-ton units. Higher-tonnage HVAC systems can cool larger areas or areas with equipment generating more heat.
The amount of air conditioning needed to cool a massive data center is much greater than you need to cool your home, primarily because of all the heat generated by the equipment. If your home air conditioner fails in the middle of summer, you may be a little uncomfortable for a while, but if the data center HVAC system fails, it can result in loss of availability and a substantial loss of money.
Mean time between failures (MTBF) is a measure of a system’s reliability. If temperatures aren’t controlled within a data center, it decreases the MTBF times, resulting in more frequent failures. In contrast, if an HVAC system keeps systems at a consistent temperature, it tends to increase the MTBF times, resulting in fewer failures.
I worked in several environments where we had a policy of shutting down all electronics when the room temperature reached a certain threshold. When we didn’t follow the policy, the systems often developed problems due to the heat and ended up out of commission for a lot longer than the AC.
Most servers aren’t in cases like a typical desktop computer. Instead, they are housed in rack-mountable cases. These rack-mountable servers are installed in equipment cabinets (also called racks or bays) about the size of tall refrigerators. A large data center will have multiple cabinets lined up beside each other in multiple rows.
These cabinets usually have locking doors in the front and rear for physical security. The doors are perforated with cold air coming in the front, passing over and through the servers to keep them cool, and warmer air exiting out the rear. Additionally, a server room has raised flooring with air conditioning pumping through the space under the raised floor.
Remember this
Higher-tonnage HVAC systems provide more cooling capacity. This keeps server rooms at lower operating temperatures, and results in fewer failures and longer MTBF times.
The 601 Version of the Study Guide
The CompTIA Security+: Get Certified Get Ahead: SY0-601 Study GuideEach of the eleven chapters presents topics in an easy to understand manner and includes real-world examples of security principles in action.
You’ll understand the important and relevant security topics for the Security+ exam, without being overloaded with unnecessary details. Additionally, each chapter includes a comprehensive review section to help you focus on what’s important.
Over 300 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:
- A 75 question pre-test
- A 75 question post-test
- Practice test questions at the end of every chapter.
Each practice test question includes a detailed explanation to help you understand the content and the reasoning behind the question. You’ll be ready to take and pass the exam the first time you take it.
If you plan to pursue any of the advanced security certifications, this guide will also help you lay a solid foundation of security knowledge. Learn this material, and you’ll be a step ahead for other exams. This SY0-601 study guide is for any IT or security professional interested in advancing in their field, and a must-read for anyone striving to master the basics of IT security.
Using Hot and Cold Aisles
Hot and cold aisles help regulate the cooling in data centers with multiple rows of cabinets. The back of all the cabinets in one row will face the back of all the cabinets in an adjacent row. Because the hot air exits out the back of the cabinet, the aisle with the backs facing each other is the hot aisle.
Similarly, the front of the cabinets in one row is facing the front of the cabinets in the adjacent row. Cool air is pumped through the floor to this cool aisle using perforated floor tiles in the raised flooring. This is the cold aisle. In some designs, cool air is also pumped through the base of the cabinets. This depends on the design of the cabinets and the needs of the equipment.
Consider what happens if all the cabinets had their front facing the same way without a hot/cold aisle design. The hot air pumping out the back of one row of cabinets would be sent to the front of the cabinets behind them. The front row would have very cold air coming in the front, but other rows would have warmer air coming in the front.
Of course, an HVAC also includes a thermostat as a temperature control and additional humidity controls. The thermostat ensures that the air temperature is controlled and maintained. Similarly, humidity controls ensure that the humidity is controlled. High humidity can cause condensation on the equipment, which causes water damage. Low humidity allows a higher incidence of electrostatic discharge (ESD).
Q. Your organization is evaluating replacement HVAC systems and is considering increasing current capacities. Which of the following is a potential security benefit of increasing the HVAC capabilities?
A. Lower MTBF times of hardware components due to lower temperatures
B. Higher MTBF times of hardware components due to lower temperatures
C. Lower MTTR times of hardware components due to lower temperatures
D. Higher MTTR times of hardware components due to lower temperatures
Answer is B. Increasing the heating, ventilation, and air conditioning (HVAC) capacity results in higher mean time between failures (MTBF) times by keeping systems at lower temperatures.
Lower MTBF times indicate more failures. Mean time to recover (MTTR) is unrelated to failures or HVAC systems.
