The easiest way to cool a data center is to install an air exchanger that generates cool air that circulates through the server room. But if you want to save money, at least in the long run, it’s a good idea to install an air exchanger in each rack and use it to cool individual racks of servers.
The latter approach is known as “rear rack cooling” and offers several advantages over traditional air cooling systems in data centers, particularly in terms of energy efficiency.
This article explains how rear rack cooling works and why you should consider it in your data center as a way to improve your approach to cooling.
What is data center rear rack cooling?
Back rack cooling in data centers uses air exchangers installed directly behind server racks to cool the servers housed in those racks.
In the rear rack cooling system, each server rack is equipped with an air exchanger. When the rack is operating, the air exchanger blows in cool air and pushes out hot air.
Comparing Rear Rack Cooling to CRAC and Direct Chip Cooling
Rear rack cooling is different from traditional data center air cooling systems known as “computer room air conditioning” or “CRAC.” This is because the rear rack cooler is targeted at the equipment that generates most of the heat, rather than blowing cool air throughout the server room. heat.
Conceptually, back rack cooling is similar to direct-chip cooling systems that circulate liquid around CPUs and other heat sources in servers. This is another way to focus on dissipating heat from equipment that generates most of the heat.
However, direct-chip cooling systems are also expensive because they require special coolants and circulators. If you want to direct cooling resources to the heat source, but don’t have the budget for direct-to-chip cooling, the next best option is rear rack cooling.
Advantages of rear rack cooling
The main benefit of rear rack cooling is the more energy efficient use of cold air. In a CRAC system, much of the air that is blown into the server room is wasted because it doesn’t come into contact with equipment that actually produces heat. In contrast, rear rack cooling systems target servers in a more localized manner, reducing waste.
Rear rack cooling also improves data center energy efficiency by allowing air exchangers to be powered down or off when servers within individual racks are not being used at maximum capacity or are inactive. (which in turn improves your PUE metric).
CRAC systems typically do not offer this option. If you are running a server, you may need to power on the entire CRAC system even when heat is minimal.
Finally, rear rack cooling is a cheaper cooling option than liquid cooling systems, at least when judged from an initial cost perspective. However, in the long run, liquid cooling may be cheaper because it requires less energy to operate.
Rear rack cooling challenges
Although rear rack cooling has multiple benefits, there are some potential hurdles to implementing it in a data center. Cooling the rear rack presents the following challenges:
- Other air exchangers: Each server rack requires its own air exchanger, so more exchangers must be installed and maintained than a CRAC system.
- Lack of backup: In most cases, there is only one heat exchanger in each rack that is cooled by a rear heat exchanger. If that exchanger fails, the rack can quickly overheat. CRAC systems can have multiple air exchangers, making them less susceptible to this type of failure, as they can continue operating even in the event of partial equipment failure.
- Energy usage: Although rear rack cooling has the advantage of energy savings, it is less efficient than liquid cooling systems. The latter is because it requires minimal energy to operate, unlike rear rack coolers that rely on fans that consume large amounts of energy.
- Space usage: Rear rack coolers consume more data center space than CRAC systems due to the air exchangers that must be installed in each rack as well as the piping that feeds the exchangers. As a result, these systems leave less space available for his IT equipment.
When should I choose rear rack cooling?
If you are looking for ways to improve the energy efficiency of your data center, but don’t have the budget or time to implement advanced cooling solutions such as direct-to-chip cooling or immersion cooling, back rack cooling is a good compromise. . It is more efficient and effective than traditional air systems that cool entire computer rooms, and it is cheaper and less complex to install than liquid cooling.
On the other hand, if you are focused on long-term results over at least a few years, liquid cooling may offer a better ROI than back rack cooling because direct-to-chip cooling and cooling are more operationally efficient. There is a possibility that it can be achieved. Immersion system.
