Hot and Cold Aisles – CompTIA Security+ SY0-401: 2.7

A data center cooling system works best when hot air is properly vented. In this video, you’ll learn how data centers use these hot and cold aisles to efficiently cool the entire computing environment.

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When we talk about hot aisles and cold aisles, we’re talking about the way that we’re engineering our data centers– where we’re putting our servers, and in which rack and what direction on the rack we’re putting our servers. If we think about the cooling system in a data center, we’ve got these HVAC units. I put one on both sides of this picture. And this is a side view of all of the racks that you have. So all of your computers, if we were to go down this aisle and look to the left or right, we would see the front or the back of servers that are facing us.

Underneath these data centers are these raised floors, and we have cold air that’s going between all these raised floor systems, and it’s blowing up into openings that we have in the floor. That is, blowing up into a set of racks where the front of our servers are. We’re essentially putting those servers back-to-back, we’re putting them front-to-front, if you will, on these servers. And the cold air is moving up, and because it’s the front of the server, the server is now pulling that cold air through the system using its fans.

On the other side of the rack is the back of the server where all the hot air is coming out, and so the back-to-back aisles are our hot aisles. That’s where all the hot air is coming out. And it’s of course raising into the top of the building, where it will then be pulled back down through our air conditioning systems and cooled again and sent through the raised floor.

So when we’re designing it to have this as optimal as possible, we’ll have certain aisles that will be our cold aisles, where we’re pulling all the air through, and then we will have our hot aisles, where all of our air has gone through our computer systems. It’s been heated up, and now we’re going to send it to the top of the building where we can recirculate it back into and make it cold again.