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Jun 08 2018

Why Our Servers Are “Super-Cool”


Sophisticated cooling technologies can help server systems to remain operative even under conditions that would normally be considered hostile to any type of IT equipment. Plus, if you take a holistic approach, they can also help to reduce a data center's carbon footprint, and enable data center operators to substantially cut costs. All of which explains why Fujitsu's PRIMERGY servers have come equipped with leading-edge cooling systems over the course of the past 14 years – and we're still counting.

Fujitsu's cooling technologies are the result of an early foray into the area of 'green IT' that started some 25 years ago. During our research we found that sub-optimal cooling might not only cause unwanted server outages and lead to a system's early demise, but tended to blow power consumption and thus energy bills out of proportion. The problem was only exacerbated by the fact that standard server and data center cooling technologies often tended to further drive up costs. For us, these findings were a starting point to make a difference and develop our own advanced technologies that tackled all these problems at once.

Fujitsu Cool-safe® and Cool-safe® Advanced Thermal Design (ATD)
Our first step in this direction was developing the original Cool-safe® Design, which was introduced in 2004. The idea was to come up with a whole new 'cooling architecture' that combined EPA-compliant power supplies, a special use of airflow channels and a mostly cable-less design to ensure that PRIMERGY servers generated less heat than competing systems and thus used 20% less power on average. In 2013, we debuted Cool-safe® ATD, an extension of the predecessor that ensured our servers would run under more extreme conditions: Earlier rack and tower models tolerated between 10 and 35 °C (50 and 95 °F) ambient temperature; the new systems could handle between 5 and 40 °C (41 and 104 °F). This helped cut air-conditioning expenses by 5 to 6% per additional degree. Cool-safe® ATD comes without time limits for extended temperature operation and most importantly does not have an influence on the warranty. Do you know situations like this in which both you as well as the hardware give up due to high temperatures? If so, you might now realize that with PRIMERGY you can achieve more.

Another three years later, we had further perfected the technology and came up with another extension: Select PRIMERGY systems are now capable of operating within an even higher temperature range of up to 45 °C (113 °F). This enabled IT departments to aim for more chiller-less data center or server room setups, with some obvious advantages:

  • Servers can be put into hotter rooms without a need to specifically cool these rooms in advance.
  • Customers can choose whether a system shall run within the regular ATD temperature range of 5 to 40 °C or the extended range of 5 to 45 °C and reap exactly the benefits they require.
  • As for potential savings on energy and cooling costs, our calculations show that increasing the temperature in a server room by 5 °C can save up to one fifth of the power (and thus cost) previously needed to run the cooling system.

Moreover, modern Fujitsu ETERNUS storage systems and networking components may also be used within this higher temperature range, enabling customers to build data centers that follow a uniform, consistent cooling concept.

Fujitsu Cool-Central® Liquid Cooling Technology (Fujitsu LCT)
While Cool-safe® and its derivatives offered clear advantages for servers in 'normal' enterprise environments, there were always scenarios where all efforts to optimize regular air-cooling would not be sufficient. Specifically, this applied to large data centers that host AI, HPC, deep learning or Big Data applications and whose number has surged massively since the turn of the millennium. These 'data bunkers' require an entirely different cooling concept which builds on the fact that liquid is a far more effective cooling medium than air, approximately by a factor of 1,000. This insight spurred the creation of our Cool-Central® Liquid Cooling Technology (Fujitsu LCT), which was developed in collaboration with Asetek, a leading provider of liquid cooling solutions for a broad range of hardware systems, from gaming PCs through workstations to OEM or DIY platforms for data centers. Fujitsu LCT is a liquid cooling solution that captures between 60% and 80% of server heat, reducing data center cooling cost by over 50% and allowing 2.5x to 5x increases in data center server density. It removes heat from CPUs, GPUs, memory modules and other high heat components within servers using water that is 40°C (105°F) hot, eliminating the need for expensive and inefficient chilled air to cool these components. In addition, excess heat drawn from the servers can be used for office heating. In short, Cool-Central® LCT enables companies to implement a closed-loop cooling system that will help them achieve excellent Power Usage Effectiveness (PUE) and Energy Reuse Efficiency (ERE) metrics and either build highly energy-efficient data centers or enhance the capabilities of existing ones.

Fujitsu Liquid Immersion Cooling (LIC)
A fairly new technology that's not yet globally available is Fujitsu LIC. With it, we've taken the idea of a water-cooled high-performance server one step further. On the outside, Fujitsu LIC looks rather simple, as the servers are simply put into a 'bath' – meaning, a sealed tank filled with a liquid coolant – so that the heat will easily disperse within the fluid. In a setup that's very similar to that of Fujitsu LCT, the coolant then flows through a closed loop system that's equipped with a heat exchanger to facilitate the cooling process, and finally back into the system for further use after it's cooled. Each 'bathtub' has 16U horizontal rack space and offers a heat output capacity of up to 30 kW. The bath is compatible with the standard 19-inch rack width specification, meaning that any air-cooled, rack-mountable server that meets these requirements can be installed with a slight modification such as to remove the fans. And since fans, along with processors and memory modules, are among the most energy-consuming server components, using the LIC solution will save considerable costs. IT departments can thus create extremely dense configurations that help them save up to 50% on data center floor space and cut power consumption by up to 40%. Fujitsu LIC allows for an easy deployment of servers anywhere because the inert fluid protects servers from harsh environments such as high temperature, high humidity, and arid and polluted air.

Nowadays, a large group of IT infrastructure vendors are offering what they purport to be power-saving, energy-efficient and cost-saving servers systems. However, few have gone as far as Fujitsu and developed an entire set of advanced, mature cooling technologies that will bring down the operating expenses in both regular and scale-out data centers. And frankly, we haven't stopped improving our products and developing new efficient solutions.

Timo Lampe


About the Author:

Timo Lampe

Senior Specialist Marketing Manager – Data Center Systems / Server


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