Data center workloads have been increasingly rapidly over the past two decades, while energy prices have continued to rise, compute technology has evolved, and enterprises are under pressure to go safe and go green. In a conservative industry, power and cooling infrastructure has not kept pace with the dramatic changes in the IT environment.
For the past decade, most data centers have relied on air to cool their computers and push the heat out of the system. Traditional data center cooling usually includes a raised floor design, then racks of IT equipment sitting on top. There’s a chiller plant at the facility. This is how traditional data center cooling works.
But this way of cooling is not very energy-efficient because the entire cooling expense, from the electrical perspective, averages about 20 to 40 percent. If we look deeper inside the server system, all the components actually consume power as the input while producing heat as the output. The whole data center cooling solution or system is to keep and maintain all this gear within the operating temperature. You don’t want it to be too hot or too cold.
Changes over the last decade
If we look at the evolution of semiconductor technology advancement in the last decade, we can see the CPU and GPU power and performance have been continuously increasing. So, for example, if I look back to 2014, traditional CPUs only consumed about 140 Watts of TDP (Thermal Design Power). Today, CPU power easily goes up to 300 Watts. And in the next two to three years, it could go up to 450 to 500 Watts.
Similarly, another big component that consumes a lot of power and generates a lot of heat, is the GPU. From 250 Watts in the last couple of years, it’s going to 400 Watts and even higher in the future. And that’s going to be a cost challenge in the traditional data center, as air isn’t very efficient in cooling that large amount of heat, because of the increasing power and increasing heat dissipation.
We are seeing a lot of new cooling technology coming out to the market. We call them alternate cooling solutions, and liquid is a very good technology to tackle this heat problem in the data center. For example, if we look at water, water is a couple hundred times more efficient in transferring heat or removing heat, compared to air.
Other technologies include immersion cooling. But it’s very important to understand the requirement and the problem we need to solve, and balance the cost efficiency and serviceability that are fit for your data center at the moment.
Efficiency of air vs water cooling
Moving heat is one of the problems to tackle, but efficiency is also very important. The traditional way using air cooling usually contributes to somewhere between 20 to 40 percent of the entire data center electricity costs.
One of the best ways in the industry to measure the efficiency is what we call PUE, the Power Usage Effectiveness. It basically looks at how much power you consume in the entire data center versus how much power you use just for IT. The smaller the number, the better. In the old data centers, usually it’s between 1.5 to 2.0 PUE. But using the new, more energy-efficient solutions, such as some of the examples we discussed, we can bring that down, e.g., to 1.2 PUE level by using a Rear Door Heat Exchanger.
Using direct warm-water cooling, the PUE can even go down to below 1.1. That is a very significant improvement from an efficiency perspective, and that also translates to very good savings from a cost standpoint, because you are cutting the bill for the data center electricity over a longer period.
From a performance perspective, using water offers another positive side effect – it allows the CPU to go turbo boost. Water cooling therefore offers higher and more consistent performance, and a lot of our high-performance computing customers are able to achieve more than 10% performance gain.
Choosing the right cooling partner
Brand and experience are very important factors in choosing the right cooling partner. Other factors are reliability and efficiency, as well as the total cost of ownership.
Customers also must choose a partner who can demonstrate experience in cooling solution deployment skills. By skills, we’re talking about customers that deploy thousands of servers in data centers. At Lenovo, our thermal engineers have been developing liquid cooling solutions since 2011 in the IBM days. And we have more than 30 patents now in water cooling technologies, being one of the industry leaders.
One of the common things I see customers ask about is reliability. After all, it is water based, and electronics don’t like water. How can we prevent and avoid water leakage and assure the reliability of the system? That is another crucial factor for the customer to consider.
As compute technology continues to evolve, there is a need to modernize cooling technologies in parallel with advancements in processing. Water cooling technologies may be just the right answer to this pressing need.