As the number of global internet users has grown, so too has demand for data centre services, giving rise to concerns about growing data centre energy use. On average, servers, and cooling systems account for the greatest shares of direct electricity use in data centres,
When trying to design cooling for data centres, the biggest challenge is the ecosystem. A data centre is a living, breathing organism, and it is difficult to design. “Cooling generally requires us to calculate and manage flows of either liquids or air and to understand how we manage hot spots and cold spots,” David Craig, CEO, Iceotope, says. “A small change here can be a large change over there.
“A significant challenge to start with is understanding what is available in the context of the facility. What climate is the data centre in? If it is hot and humid, then it needs much more energy to cool, for example. And then there is the envelope of the building with questions surrounding everything from the height and the physical fabric of the building, as it was designed, to understanding what it is that you are going to cool inside. Knowing this allows you to navigate complex designs in a manner which demonstrates good understanding. The challenge, of course is that it is always changing.”
The challenge of higher power processing
Today’s demands for IoT, artificial intelligence, machine learning, big data analytics, and edge applications are driving the increase in chip and rack densities. Servers are demanding high-power GPUs and CPUs to meet their business’ processing needs with these chips reaching thermal design power (TDP) of 400W.
“Increasing chip densities just make things that much hotter,” Craig says. “With increasing densities comes faster RAM and faster networking. This is not only making the processors hotter, but also means that the associated kit is generating tens and hundreds of kilowatts of additional heat inside. Heat recovery becomes much more difficult. Cooling air and blowing it is not only more consumptive of energy and other resources reversing efficiencies, it also creates quite a hostile environment for the electronics. You have got massive fluctuations and that can cause failures.
“We are going to have to reverse many of the efficiency gains we have had. There is a limit to how air can cool the chips as they get hotter, and when it is reached, you just must use better thermal management.”
Living on the edge
Another trend that is sweeping through the computing sector is edge processing, and according to Craig that presents a slightly different challenge. “It’s about processing being done in different places for a set of different reasons, usually bandwidths, data sovereignty or criticality,” he says. “If you have a major engineering department with thousands of engineers working on CAD drawing files across the globe, then you start to have real issues. They click on download, go and get a coffee, talk to their kids for a little while and come back half an hour later and finally they get their file. You need local compute for that.
“Edge is going to be regional data centres splitting down into micro data centres, splitting down into IoT devices. The political legislative climate also requires us often to have data in specific places and often local to us. Finally, criticality. If you think about a building that you may be in, an office block perhaps, how secure would you feel if you knew that the fire control system for the building was controlled in the cloud? That must be local.”
The role of cooling in sustainable data centres
As the energy required for cooling typically accounts for about a third of all the energy used in a data centre it is a crucial element of its sustainability profile. “In a recent project, Iceotope were tasked with taking 14 servers in a rack and making them more energy efficient,” Craig explains. “Just by removing the server fans and replacing them with pumps, that one simple change, our approach saved two and a half kilowatts of energy just in that one rack.
“There are some data centre owners making sustainability a key part of their offering and building leadership and new business models around that. There are many other operators doing their best to run things efficiently but most decisions will still be made, quite rightly, around risk, cost, and performance. The industry needs to give better understood and costed solutions so that the balance between those three can be safely navigated.”
The balance between these is not difficult to calculate, the issue becomes the risks around the decision. “It is all about the risk,” Craig adds. “Measuring, understanding, and mapping it is applied engineering. The real issue becomes ‘where does the risk lie?’ Because you are making multi-billion-dollar decisions and people are rightly, extremely cautious of making the wrong one. You then end up with the ‘let us see what happens in the market’ approach. That approach of being a fast follower works a lot of the time, but every so often there is a technology trend that comes where if you do that, you really mess up. I believe this is one of those waves where leadership is essential and will win through.
“The whole industry needs to move forward together. There is no point in having roads without cars to drive on them. A sense of momentum has come into the industry to drive it forward. That momentum is growing, but it has not quite hit the tipping point yet.”
The path to sustainable cooling
There are a lot of emerging technologies for cooling but to date there is no one clearly defined direction. Much like the renewable energy sector there are a myriad of technologies chasing a piece of the action, and it could well be that many of these will have a role to play. “I think it is very important to recognise that we are living in a large and complex world,” Craig concludes. “A world where many people will have different use cases, different, very rational reasons for selecting multiple vendors, multiple technologies and choices.
“We are going to live as a very hybridised world between air cooling and liquid cooling, and there will always be people who passionately love one cooling style over another.
“I believe the unique thing about Iceotope is not just our set of technologies, but a business model that removes the risk around the supply chain, autonomy in sourcing, scale and serviceability. Most cooling solutions are simple point solutions, we are unique in having developed a platform that can be applied across the whole estate and at any scale. No other cooling technology, even air does that. But we do it without those upper thermal limits.”
David Craig is one of the speakers at Digital Infra Networks Knowledge talk on ‘The role of innovative cooling technology in the sustainable data centre’ that is released on December 8th. Sign up here to listen to the presentations on the day or later on demand.
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