Some examples of such disruption, relevant in the data centre, are flash memory which enabled a step-change in storage performance (latency in particular); silicon-integrated fiber optics that led to infrastructure designs using ultra-high bandwidth but affordable, low-power links; and lithium-ion and other battery chemistries that make compressed, distributed power architectures and peak-shaving possible.
451 Research considers direct liquid cooling to be one of the next disruptive technologies in the data centre. The concept has been around IT in various forms for some time, keeping workstations quiet and cooling mainframes at the heart of many mission critical enterprise applications. Supercomputers also tend to favor liquid cooling, because they pack electronics at such density that airflow becomes an issue.
Air is still the dominant medium of cooling in data centres, but 451 Research expects this is about to change. After years of development and feedback from facility operators, datacenter-class liquid cooling techniques are now well-honed and easier to integrate than before. Today, options go well beyond water cold-plates and the original immersion systems that were either costly or used unreliable coolants and now include chassis-level immersion cooling which can support cold-plate techniques, too.
Liquid cooling will become more standard in data centres for five reasons:
More IT for the same amount of power – Peak power for liquid cooling is a small fraction of that of air, which translates into a much leaner power infrastructure. Liquid cooling also reduces or eliminates the need for IT system fans, which also consume energy (5-10% of the load on average). Liquid cooling also allows for 25-50% more IT capacity within a given power envelope. Wherever power capacity is limited, this factor alone can be decisive.
Higher application performance – In the past 10 years processors have become increasingly dynamic and configurable in their speeds, matching individual core frequencies to workload demand within the available power and cooling budget. As a result, better cooling can translate to more performance, particularly when it comes to workload peaks when compute may become a bottleneck and processing speed matters the most. Modern server processors have a configurable thermal budget which the customer can turn up or down, to match the desired performance and power. Liquid cooling helps processors and accelerators achieve higher peak performance levels for longer.
Lower operational risks – Next-generation liquid cooling systems reduce, not add, risks to datacenter operations – both for IT and facilities equipment. On the IT side, this is because liquid cooling in general provides better thermal stability and lower operational temperature for electronics, while immersion cooling also protects from humidity, which is also a big factor when it comes to component failure rates but can be energy intense to control. Hard drives are particularly prone to failures as a result of either high temperatures or excess humidity. Liquid cooling can address both and reduces the risk of any data loss and lower storage performance. Less frequent maintenance requirements mean fewer visits by field engineers which also leads to reduced human errors. Liquid cooling helps the facility operations by reducing the amount of equipment to maintain: the primary IT load does not depend on compressors, fans or water supply. Because of the thermal efficiency of liquid cooling, it does not operate at the margins of climatic conditions and protects against adverse climatic conditions no matter how hot and humid – or arid – the location is. This contribution to operational sustainability of liquid cooling is often overlooked.
And the installation of liquid cooling does not necessarily mean a wholesale change to the design, build and operational regimes of data centres. One of the key developments of recent years is the availability of liquid cooling approaches that minimize integration friction by offering the ability to fit into existing IT cabinet standards, mix and match air and liquid (cold plate or immersion) cooling options, while retaining much if not all of the established supply chain. Some types of precision delivery immersion cooling use a sealed server chassis but can also be used for cold-plate style installations.
Environmental and social benefits – Liquid cooling makes better use of resources than air cooling, due to its lower energy need (which also translates to a lower carbon footprint) and zero water consumption. Better still, liquid cooling can easily support higher density cabinets to compress the data hall, while doing away with large air-cooling equipment such as chillers, air handlers and cooling towers, contributing further savings on real estate. Smaller, silent and more power efficient, liquid cooling makes the datacenter friendlier to the environment and more palatable to local residents who, in some cases, strongly oppose further datacenter developments in their neighbourhoods.
451 Research takes the line that further efficiency or cost improvements with air cooling are marginal at best, and this is also becoming a limiting factor in application performance. All the while, operational and environmental sustainability, as well as social considerations, will only get stronger over time – as will demand for liquid cooling technologies.