Liquid cooling: decisions, types, approaches.

By Nicole Hemsoth

June 11, 2012

Despite world economic turmoil of the recent severe European crisis, the demand for high performance computing services stays on the rise. Companies and institutions progressively see computational power as a source of competitive advantage and in many cases as the only optimal solution for many scientific and business challenges, from high energy physics to big data. This trend has brought an unprecedented rise in demand for high computational power. This is posing some sound energy and thermal management challenges.

The energy problem in data centres is two sided. On the one hand, data centres have a problem of energy consumption, which enlarges bills also in countries where the cost of energy is relatively low. On the other hand, there is a problem of peak power demand, so, in other words, a problem of availability.  Megawatt installations are not so uncommon anymore, meaning that a request of power similar to the one that has traditionally belonged to the heavy industry sector is becoming almost the norm, in some occasions requiring special arrangement for power systems and electrical lines.

Thermal management is exacerbated by another trend: density. In many cases, rack powers of 30 kW are well beyond what legacy air cooling can handle. In the modern HPC, the high powers in play often leave few options but resorting to some form of water cooling.

Liquid cooling has many advantages, which derive from the much higher heat capacity per unit volume of water compared to air (we are talking about a factor of 3500 times higher). Liquid cooling implies higher densities, energy savings and the possibility to reuse the thermal energy that the water extracts from the IT equipment. Some additional advantages can be found in terms of lower noise levels, less vibrations and close control of electronics temperatures.

The best approach in deciding what type of cooling to implement is to consider alternatives in relation to technical and business needs, the type of air and liquid cooling system available within budget and a series of variables that play an important role in the decision: the desired density versus space availability, new construction versus existing construction, the proximity to natural sources of cold water like rivers and lakes, the local climate, the cost of energy and the thermal energy recovery possibilities.

For instance, high performance high density requirements may leave little choice than liquid cooling to efficiently manage the extraction of the heat from the supercomputers. While, if the data centre has an economizer and the climate is best suited to air-side economizers (mild temperatures and moderate humidity) than an air cooled DC may have more sense. 

Deciding the cooling system may also take in consideration the type of water cooling to be installed. There are solutions that simply create an extension of the existing liquid-cooling loop closer to the IT equipment like in the case of liquid cooled racks (liquid cooled door, closed-liquid rack). In other solutions, in-row units are embedded in rows of data center cabinets, providing localized air distribution and management. Alternatively, overhead cooling suspends from the ceiling complements a hot aisle/cold aisle arrangement. As hot air rises from the hot aisle, the overhead cooler captures it, conditions it, and releases it back to the cold aisle

More effective cooling can be reached when the liquid is brought in the near proximity of the electronic components like in the case of submerged cooling, spray cooling or direct (embedded) cooling.

In the first case, the electronic components are immerged in oil and water which is kept in circulation through small pumps. In the second, the water is vaporized and tiny drops of water fall on the electronics evaporating immediately and taking away a lot of heat. In the latter, water is taken through metal plates or micro pipes to direct contact with processors, memory and other components.

Another distinction is normally made between hot and cold liquid cooling. The definition of hot liquid cooling can be vary. In Eurotech we think that hot liquid cooling means the technology capable of using a liquid (e.g. water) with a temperature above the server room temperature.  We also accept that, pushing the bar up in terms of max coolant temperature, hot liquid cooling may take place when the water is hot enough to allow thermal energy reuse.

In any kind of liquid cooling, one aspect that needs careful attention is the risk of leaking. This is an issue because the electronic components are upgraded on a routine basis resulting in many systems with the need to disconnect and reconnect the liquid carrying lines. Also, there is the need to consider whether cooling with water brings on all of its potential. For instance, resorting to chillers to cool the water will allow density, but limit the energy savings that are maximized with hot water cooling technologies, thanks to air conditioning avoidance. However, it is no news that new powerful processors with TDP of 150W may require coolant temperatures lower that the ones guaranteed by free cooling in warm climates. An additional downside of increasing water temperature may be the higher operating temperature of electronic components.  This risk needs to be balanced by the advantages coming from levelling temperatures on the mother board and avoiding hot spots at data center level.

Eurotech approach

Eurotech has developed liquid cooling systems for more than 7 years and it was the first in the market to offer a hot liquid cooling with high serviceability. Eurotech Aurora supercomputers have been liquid cooled since product one and day one, allowing for precious competences and know how to be waived within the fabric of the organization. This experience helped the development of our idea of liquid cooling.

Eurotech liquid cooling is:

Hot. That means using hot water of 50+ °C, balancing customer needs, density targets, data center temperature and site temperature/humidity profiles. Eurotech delivers to customers the liquid cooling solution that allows utilizing the water at the maximum temperature possible across the year. 

Direct.  The cooling takes place inside the rack, where aluminum cold plates are put in direct contact with the components, allowing to maximize the heat transfer and heat extraction efficacy. The good side effect is to level out temperatures on board avoiding hot spots.

Green. Eurotech aims to utilize free coolers (liquid to air heat exchangers) in any climate zone. Solutions are designed to avoid air conditioning, while maintaining the highest density possible, and to exploit, if required and wherever it is possible, thermal energy recovery.

Comprehensive. The “cold plates” cool processors, memory, FPGAs, power supply, switches and any other heat generating component, including GPUs or other accelerators. This means that there is not a single heat source in the rack that is not cooled, preventing hot spots at DC level.

Serviceable. Eurotech Aurora HPC boards are hot swappable despite being water cooled thanks to connectors that seal instantaneously when a node card is extracted for maintenance or management purposes. The node cards are blades that a single person can easily manage.

Safe. Eurotech understand that it is imperative to keep water away from electronics. For this reason we have spent several years to develop a system that doesn’t leak and to mature those competencies that guide our customers into the correct and trouble free maintenance of the liquid cooling infrastructure.

Indeed, one of the Eurotech focus is on correct liquid cooling operations and maintenance, which is fundamental to preserve the system safety and integrity and keep performances at top levels.

“The maintenance of liquid cooling systems is not a daunting task” says Paul Arts, Eurotech technical director “but it requires following guidelines many of them are conveniently collected by Ashrae. At Eurotech, we assist our customers in approaching hot water cooling, designing the systems and training the customers in operations and maintenance. If have to spare my 2 cents, areas I would focus my attention are water quality, anti-corrosion precautions, flow rate and dew point temperatures”

Eurotech has experienced that correct operations maximize the life not only of the cooling system but also of the electronic components, rounding up the advantages of using hot water cooling. Eurotech believes in liquid cooling as an approachable and concrete solution for facing energy and thermal issues, especially in those contexts that are climatically unfavourable.

http://www.eurotech.com/en/hpc/

Subscribe to HPCwire's Weekly Update!

Be the most informed person in the room! Stay ahead of the tech trends with industy updates delivered to you every week!

SRC Spends $200M on University Research Centers

January 16, 2018

The Semiconductor Research Corporation, as part of its JUMP initiative, has awarded $200 million to fund six research centers whose areas of focus span cognitive computing, memory-centric computing, high-speed communicat Read more…

By John Russell

US Seeks to Automate Video Analysis

January 16, 2018

U.S. military and intelligence agencies continue to look for new ways to use artificial intelligence to sift through huge amounts of video imagery in hopes of freeing analysts to identify threats and otherwise put their Read more…

By George Leopold

URISC@SC17 and the #LongestLastMile

January 11, 2018

A multinational delegation recently attended the Understanding Risk in Shared CyberEcosystems workshop, or URISC@SC17, in Denver, Colorado. URISC participants and presenters from 11 countries, including eight African nations, 12 U.S. states, Canada, India and Nepal, also attended SC17, the annual international conference for high performance computing, networking, storage and analysis that drew nearly 13,000 attendees. Read more…

By Elizabeth Leake, STEM-Trek Nonprofit

HPE Extreme Performance Solutions

HPE and NREL Take Steps to Create a Sustainable, Energy-Efficient Data Center with an H2 Fuel Cell

As enterprises attempt to manage rising volumes of data, unplanned data center outages are becoming more common and more expensive. As the cost of downtime rises, enterprises lose out on productivity and valuable competitive advantage without access to their critical data. Read more…

When the Chips Are Down

January 11, 2018

In the last article, "The High Stakes Semiconductor Game that Drives HPC Diversity," I alluded to the challenges facing the semiconductor industry and how that may impact the evolution of HPC systems over the next few years. I thought I’d lift the covers a little and look at some of the commercial challenges that impact the component technology we use in HPC. Read more…

By Dairsie Latimer

SRC Spends $200M on University Research Centers

January 16, 2018

The Semiconductor Research Corporation, as part of its JUMP initiative, has awarded $200 million to fund six research centers whose areas of focus span cognitiv Read more…

By John Russell

When the Chips Are Down

January 11, 2018

In the last article, "The High Stakes Semiconductor Game that Drives HPC Diversity," I alluded to the challenges facing the semiconductor industry and how that may impact the evolution of HPC systems over the next few years. I thought I’d lift the covers a little and look at some of the commercial challenges that impact the component technology we use in HPC. Read more…

By Dairsie Latimer

How Meltdown and Spectre Patches Will Affect HPC Workloads

January 10, 2018

There have been claims that the fixes for the Meltdown and Spectre security vulnerabilities, named the KPTI (aka KAISER) patches, are going to affect applicatio Read more…

By Rosemary Francis

Momentum Builds for US Exascale

January 9, 2018

2018 looks to be a great year for the U.S. exascale program. The last several months of 2017 revealed a number of important developments that help put the U.S. Read more…

By Alex R. Larzelere

ANL’s Rick Stevens on CANDLE, ARM, Quantum, and More

January 8, 2018

Late last year HPCwire caught up with Rick Stevens, associate laboratory director for computing, environment and life Sciences at Argonne National Laboratory, f Read more…

By John Russell

Chip Flaws ‘Meltdown’ and ‘Spectre’ Loom Large

January 4, 2018

The HPC and wider tech community have been abuzz this week over the discovery of critical design flaws that impact virtually all contemporary microprocessors. T Read more…

By Tiffany Trader

The @hpcnotes Predictions for HPC in 2018

January 4, 2018

I’m not averse to making predictions about the world of High Performance Computing (and Supercomputing, Cloud, etc.) in person at conferences, meetings, causa Read more…

By Andrew Jones

Fast Forward: Five HPC Predictions for 2018

December 21, 2017

What’s on your list of high (and low) lights for 2017? Volta 100’s arrival on the heels of the P100? Appearance, albeit late in the year, of IBM’s Power9? Read more…

By John Russell

US Coalesces Plans for First Exascale Supercomputer: Aurora in 2021

September 27, 2017

At the Advanced Scientific Computing Advisory Committee (ASCAC) meeting, in Arlington, Va., yesterday (Sept. 26), it was revealed that the "Aurora" supercompute Read more…

By Tiffany Trader

AMD Showcases Growing Portfolio of EPYC and Radeon-based Systems at SC17

November 13, 2017

AMD’s charge back into HPC and the datacenter is on full display at SC17. Having launched the EPYC processor line in June along with its MI25 GPU the focus he Read more…

By John Russell

Japan Unveils Quantum Neural Network

November 22, 2017

The U.S. and China are leading the race toward productive quantum computing, but it's early enough that ultimate leadership is still something of an open questi Read more…

By Tiffany Trader

Nvidia Responds to Google TPU Benchmarking

April 10, 2017

Nvidia highlights strengths of its newest GPU silicon in response to Google's report on the performance and energy advantages of its custom tensor processor. Read more…

By Tiffany Trader

IBM Begins Power9 Rollout with Backing from DOE, Google

December 6, 2017

After over a year of buildup, IBM is unveiling its first Power9 system based on the same architecture as the Department of Energy CORAL supercomputers, Summit a Read more…

By Tiffany Trader

Fast Forward: Five HPC Predictions for 2018

December 21, 2017

What’s on your list of high (and low) lights for 2017? Volta 100’s arrival on the heels of the P100? Appearance, albeit late in the year, of IBM’s Power9? Read more…

By John Russell

GlobalFoundries Puts Wind in AMD’s Sails with 12nm FinFET

September 24, 2017

From its annual tech conference last week (Sept. 20), where GlobalFoundries welcomed more than 600 semiconductor professionals (reaching the Santa Clara venue Read more…

By Tiffany Trader

Chip Flaws ‘Meltdown’ and ‘Spectre’ Loom Large

January 4, 2018

The HPC and wider tech community have been abuzz this week over the discovery of critical design flaws that impact virtually all contemporary microprocessors. T Read more…

By Tiffany Trader

Leading Solution Providers

Perspective: What Really Happened at SC17?

November 22, 2017

SC is over. Now comes the myriad of follow-ups. Inboxes are filled with templated emails from vendors and other exhibitors hoping to win a place in the post-SC thinking of booth visitors. Attendees of tutorials, workshops and other technical sessions will be inundated with requests for feedback. Read more…

By Andrew Jones

Tensors Come of Age: Why the AI Revolution Will Help HPC

November 13, 2017

Thirty years ago, parallel computing was coming of age. A bitter battle began between stalwart vector computing supporters and advocates of various approaches to parallel computing. IBM skeptic Alan Karp, reacting to announcements of nCUBE’s 1024-microprocessor system and Thinking Machines’ 65,536-element array, made a public $100 wager that no one could get a parallel speedup of over 200 on real HPC workloads. Read more…

By John Gustafson & Lenore Mullin

Delays, Smoke, Records & Markets – A Candid Conversation with Cray CEO Peter Ungaro

October 5, 2017

Earlier this month, Tom Tabor, publisher of HPCwire and I had a very personal conversation with Cray CEO Peter Ungaro. Cray has been on something of a Cinderell Read more…

By Tiffany Trader & Tom Tabor

Flipping the Flops and Reading the Top500 Tea Leaves

November 13, 2017

The 50th edition of the Top500 list, the biannual publication of the world’s fastest supercomputers based on public Linpack benchmarking results, was released Read more…

By Tiffany Trader

GlobalFoundries, Ayar Labs Team Up to Commercialize Optical I/O

December 4, 2017

GlobalFoundries (GF) and Ayar Labs, a startup focused on using light, instead of electricity, to transfer data between chips, today announced they've entered in Read more…

By Tiffany Trader

HPC Chips – A Veritable Smorgasbord?

October 10, 2017

For the first time since AMD's ill-fated launch of Bulldozer the answer to the question, 'Which CPU will be in my next HPC system?' doesn't have to be 'Whichever variety of Intel Xeon E5 they are selling when we procure'. Read more…

By Dairsie Latimer

Nvidia, Partners Announce Several V100 Servers

September 27, 2017

Here come the Volta 100-based servers. Nvidia today announced an impressive line-up of servers from major partners – Dell EMC, Hewlett Packard Enterprise, IBM Read more…

By John Russell

Intel Delivers 17-Qubit Quantum Chip to European Research Partner

October 10, 2017

On Tuesday, Intel delivered a 17-qubit superconducting test chip to research partner QuTech, the quantum research institute of Delft University of Technology (TU Delft) in the Netherlands. The announcement marks a major milestone in the 10-year, $50-million collaborative relationship with TU Delft and TNO, the Dutch Organization for Applied Research, to accelerate advancements in quantum computing. Read more…

By Tiffany Trader

  • arrow
  • Click Here for More Headlines
  • arrow
Share This