Front line research: Why build a Generic Server Wind-tunnel?

In 2021, Techbuyer began a new project with the UK Research Institute to develop improved methods for measuring and improving data centre energy efficiency. You can read about the team and what it hopes to achieve here.

As part of that work, the research team have built a climate chamber that allows them to test the effect of temperature and air pressure on server performance. Dr Kat Burdett, who designed and built the wind tunnel, will take us through some of the practicalities of this in her blog series. In this first section, she explores the rationale behind the climate chamber.  

In a world where a digital lifestyle is increasingly prevalent – and we begin to see an internet of not just people but of things - it is paramount to minimize the energy impact of digital infrastructure. Reducing the power cost of Data Centres (DCs) is not just the financial prerogative of individual companies, but a moral and environmental responsibility for the industry as a whole. However, doing this can be a struggle.

“The universally adopted metric for energy efficiency of a data centre is PUE or Power Usage Effectiveness. PUE is a ratio between the energy usage of a data centre as a whole and the energy draw of the IT equipment.  A PUE of 2 means that the DC would be paying as much to power their cooling infrastructure as they were to power their IT itself. There is an intuitive belief that a lower PUE is tantamount to a more efficient DC. 

The historical impetus has been to achieve lower and lower PUE – as much for bragging rights as for actual environmental concerns. This has driven improvements to the cooling and supporting infrastructure of DCs. Now, there is a growing awareness that we need to look at the IT infrastructure for efficiency gains. This is a major focus of our research.  

We have built a number of tunnels for testing servers since 2015, with upgrades to the latest currently in the works. The first was created for my PhD project, the second was built at RISE in Sweden as a collaboration between them and my previous employer Edgetic, and the third iteration was assembled at a warehouse Unit in Leeds.

Each tunnel has shared the same basic goal; to be able to control the thermal environment that a data center server is in for the purpose of better understanding that server and the effect temperature and other environmental concerns has on it. The reason we are doing this is that we can find the most effective environment for a server to operate efficiently and save energy in various ways.

Firstly, it allows us to reduce the energy draw of the servers themselves (which are responsible for most of the electricity usage in a data centre). Secondly, it allows us to understand which temperature and pressure produces the highest level of efficiency in individual makes and models. Thirdly, this then enables us to model better solutions for supporting infrastructure, and reduce the energy spend of the whole building.

At the moment, standards around the operating temperatures for data centres provided by ASHRAE are an envelope. As long as data centres operate between the top and lower end, few people consider the impact of the degrees in between. Our team is working to explore this in more detail utilising an experimental climate chamber to profile the behaviour of a server under the different thermal conditions. We aim to provide the industry with tools to make decisions on IT that satisfy the requirements of the DC in the most energy-efficient way possible. That means building our own mini, controlled climate in the form of a wind tunnel. It can be adapted to any make, model and generation of server and will enable us to look at trends as a result.”

The third full iteration of the wind tunnel in situ at Unit 2 in Leeds. Visible is the water-air heat exchanger in the duct on the left, the tunnel itself on the right, and the original datalogger unit atop the server section.

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