- Is Your Cable Management Impacting Airflow in your Data Center?

So what is the goal of airflow management? The goals are twofold: preventing large variations in air temperature and air pressure. This means separating supply air mass and return air mass through design.

Just grouping cables together with a zip tie does nothing to facilitate this and can actually result in a serious disruption of airflow. What happens as a result? Lower fan efficiency, higher HVAC costs, potential changes in pressure, and even equipment damage or failure.

The current problem? Because more people are working from home or adopting the work from anywhere culture as a result of COVID, data centers are having to increase capacity, and they may not have additional floorspace to accommodate more server racks. Since conventional cable management can use up as much as 25% of rack space, this means that intelligently designed rack cable management is more important than ever.

Because of this it is important that cable management and airflow be looked at as an entire package. There are two areas of cable management in a data center: cable management in the room itself, essentially the cables that run between server racks, and rack cable management.

Of course, we must manage the cables that run between server racks, and they have to go somewhere. There are essentially two approaches, and both can create unique issues. They are running cables under the floor or running cables overhead.

Perhaps the most common is underfloor cabling where the underfloor space is also used for cool air transport. This is usually a very efficient method for separating supply and return air masses. However. When you put more holes in the floor, say to accommodate more server racks, the risk of “bypass air” or mixing the two airflows increases.

Why not just go with overhead cable management then? In some cases, this works exceptionally well, although there are budget and logistical obstacles. The height of the cable pathway is also often an issue.

Think of it this way. If your data center uses the underfloor space for air system management and not cable management, overhead pathways are fine. If they are placed too high though, the warm return air underneath can actually get too turbulent, resulting in a mix of the supply and return air. This created a temperature bypass.

But this bypass also can increase variations in pressure throughout the data center, causing the fans and other mechanisms to work harder. It’s a delicate balance.