Datacenter Airflow Management Guide
Running a data center comes with plenty of challenges. And something that frequently floats to the top of those challenges is heat management. Keeping those powerful devices cool requires careful planning and constant effort. And it gets expensive.
With applied airflow management, you can find solutions that help you stay on top of cooling, keeping costs low, designs efficient, and productivity up.
What Is Airflow Management?
This isn’t a great mystery. It’s how you manage the flow of air in a data center, right?
Another way to put it is that it is the strategy you use to control air movement in your data center. More specifically, it’s a strategy that helps minimize the costs associated with cooling the center.
After all, the majority of power consumption in most data centers comes from cooling, not from the communications hardware. If you can lower cooling needs, you can save a lot of money over sustained periods of time.
So, with a little strategy, airflow management can help you keep your equipment cool, costs down, longevity up, and stress lower.
Why Does Airflow Management Matter?
Even putting aside the benefits listed above, airflow management is important because data centers are large, expensive, and complicated. More importantly, controlling temperatures is critical. If equipment gets too hot, it fails. From that perspective, anything that helps with temperature management is important.
More than that, airflow management can help you slow the accumulation of heat and even design passive cooling into your data center that can help equipment run well even if there are failures with your active cooling systems.
Airflow management can make maintenance across the data center easier and more efficient.
How to Manage Airflow
Ok. How do we do it? What are the best practices for airflow management? It turns out that there are five specific practices that can make a world of difference in any data center.
Hot and Cold Aisles
This idea has been around for a while (it was developed by IBM in the early 90s), and it’s potent, but it’s not always intuitive. It turns out that the simplest and most powerful efficiency that you can build into a data center is hot and cold aisles.
To do this, face the front of one server rack toward the front of another, and do that for an entire aisle. Where the backs of the racks face, pair them with the backs of more servers. So, if you walk down an aisle, you will either see only fronts of racks or backs of racks but never both.
This is important because your servers all draw air and vent heat in the same way. Cool air is drawn through the front, and hot air is vented out of the back. So, your front-facing aisles will be cooler than the back-facing aisles, creating your hot and cold setup.
What does this do?
Well, the ambient air temperature in the cold aisles will be lower than the aisles that have all of that heat exhaust. That means that the intake air for every server is colder than the average temperature of the room itself. Since you’re taking cold air in to run across the device, the cooling process is more efficient. As a result, you don’t need to use air conditioning (or other cooling methods) nearly as much to maintain optimal operating temperatures.
2. Use Barriers Between Aisles
After going through that trouble to create hot and cold aisles, you want to make the most of them. The thing is, server racks usually don’t extend all the way to the ceiling. As a result, the air from your hot and cold aisles can mix pretty freely, and that destroys your efficiency gains.
The simple solution is to create barriers that do run from floor to ceiling. This reduces air mixing and helps your cool aisles stay cool.
3. Exploit Thermodynamics
There’s this idea that hot air rises and cold air falls, and while that’s kind of true, data centers are large spaces with dynamic airflow (despite your efforts to the contrary), and hot air won’t always rise predictably and cold air won’t always fall where you want it.
What this means is that ceiling vents aren’t always the best way to deliver cool air to your servers. Instead of designing everything around ceiling vents by default, think about how high your servers are. If they reach up to the ceiling, then ceiling vents are fine. If they’re lower, consider floor vents to get more direct delivery of cooled air.
You can double down on this idea by creating air exhausts in the room where they are needed most (often in the ceiling).
4. Account for Hot Spots
Since hot and cold air don’t always behave the way you want, your best bet is to pay attention to temperature ranges across your server racks. If you find hot spots, address them directly. You can use containment chambers to attack hotspots and get temperatures down.
For a simpler solution, you can place external fans where you need them to move air as you see fit. You can blow cool air directly at your hot spots or help clear out heat exhaust. A few fans can make a world of difference.
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