As the world continues to generate an overwhelming amount of data from sources like the Internet of Things, video content, and artificial intelligence (AI), it comes as no surprise that projections estimate a daily data generation of 463 exabytes by 2025.
The evolving landscape of data access and interaction has a significant impact on data processing and storage, leading to predictions that global data storage will exceed 200 zettabytes in the near future, with cloud storage accounting for half of this volume.
Hyperscale data centers and their storage infrastructure face a unique challenge. Cloud data centers rely heavily on hard disk drives (HDDs), which store approximately 90% of their exabytes.
HDDs, renowned for their reliability, are typically housed in a 3.5-inch form factor, providing cost-effective storage solutions at scale. The latest HDD models boast a capacity of 26TB, and by the end of the decade, capacities are expected to surpass 120TB while maintaining the same 3.5-inch form factor.
This exponential growth in data storage, however, requires improved thermal cooling solutions. Increased data storage requires more disk spinning, higher-speed motors, and additional actuators, all of which result in elevated power consumption and heat generation.
As power consumption rises, so does heat production. Additionally, the integration of helium technology in hard drives over the past decade has improved performance by reducing disk drag and ensuring sealed units.
Moreover, data center owners face the challenge of Environmental, Social, and Governance (ESG) compliance. Data centers currently consume around 1% of global electricity demand, with cooling accounting for more than 35% of total energy consumption in these facilities.
Consequently, data center operators are under pressure to reduce their energy consumption and enhance sustainability.
Data Center Cooling Technologies: A Comparison
When comparing the prominence of various cooling technologies, traditional data centers have long favored air-cooling methods. This involves pulling increasing volumes of airflow through equipment chassis to dissipate heat.
Globally, air cooling is widely used, well-understood, and deeply ingrained in data centers. However, as data volume continues to escalate, it is becoming increasingly apparent that air cooling alone may not ensure an appropriate operating environment for energy-dense IT equipment.
Liquid cooling technologies are emerging as highly efficient solutions for heat dissipation from IT equipment. One notable example is Precision Liquid Cooling, which circulates small volumes of dielectric fluid across server surfaces, effectively removing almost 100% of the heat generated by electronic components.
Precision Liquid Cooling eliminates performance limitations associated with hotspots and overcomes the constraints of front-to-back air cooling or bottom-to-top immersion systems. While Precision Liquid Cooling was initially applied to cooling server components within sealed chassis, it has also proven to be suitable for cooling high-density storage devices such as HDDs.
High-density storage demands
In traditional high-density HDD setups, air is drawn from the ‘cold aisle’ in front of the rack and through each JBOD via fans mounted at the rear of the device. The air is heated as it passes over each row of disks and is then exhausted into the ‘hot aisle’.
The air gets hotter as it passes each row of disks, resulting in a tested HDD temperature differential of up to 20°C between the disks at the front and back in high-capacity and densely packed JBODs.
Such variations in temperature distribution combined with vibrational effects from the powerful fans pulling air through the rows of HDDs could lead to inconsistent wear and tear on the drives, resulting in unpredictable disk errors. It also means that data center operators must provision air flow and air temperature for the hottest disks at the rear of the JBOD and overcool the front HDDs, leading to operational inefficiency.
Temperature variances can also occur vertically within a rack, with lower devices consuming cooler airflow from floor tiles, this is eliminated with a rack-based liquid cooling approach which cools every disk evenly front to rear, top to bottom.
Through liquid cooling, these challenges can be mitigated, and consistency can be improved. A study conducted in 2022 by Meta showcased how an air-cooled, high-density storage system was re-engineered to leverage single-phase liquid cooling.
The study demonstrated the following benefits of Precision Liquid Cooling for HDD racks:
- Temperature variance among all HDDs was only 3°C, regardless of their location inside the JBODs.
- HDD systems could operate reliably in rack water inlet temperatures up to 40°C.
- System-level cooling power accounted for less than 5% of the total power consumption.
- In addition to providing temperature consistency, liquid cooling enables the cooling of all disks at higher water temperatures, eliminating the need for chilled water supply to the units. This reduced demand for electrical power, water, and space, as well as reduced audible noise, results in a lower cost of ownership (TCO) and improved environmental sustainability compliance for data center operators.
Developing Storage Systems That Enable Innovation
As the demand for data storage continues to surge, cloud service providers must find efficient ways to cool their equipment. Liquid cooling for high-density storage is emerging as a viable alternative, ensuring consistent cooling temperatures for drives, minimizing fan-induced vibrations, reducing overall power consumption, and improving ESG compliance.
In an era where data center operators face increasing pressure to reduce energy consumption and improve sustainability metrics, this technology not only contributes to environmental preservation but also aligns with business objectives.
Despite air cooling's continued importance, storage manufacturers must embrace innovative alternatives like liquid cooling in the near term. Demonstrations of liquid cooling technology, such as the one conducted by Meta, play a crucial role in driving adoption and ensuring seamless integration into storage systems.
Looking ahead, relying solely on increasingly powerful fans to cool racks is not a sustainable long-term solution. Data halls cannot expand limitlessly, and cooling costs for racks are escalating. Consequently, storage solutions designed to leverage Precision Liquid Cooling offer a more cost-effective alternative, featuring smaller footprints, reduced material usage, faster performance, and improved reliability.
This not only delivers TCO benefits but also contributes to enhanced ESG value. By optimizing today's technology and removing limiting factors in data storage methods, we can overcome global challenges and pave the way for a better future.
Neil Edmunds is Director of Innovation at Iceotope Technologies.