浸没式液冷，让服务器像PC一样超频
Overclocking the Cloud? Immersion Cooling Could Enable Faster Servers
October 27 , 2021 By RICH MILLER
译 者 说
沸腾的液体带走微软数据中心的计算机服务器产生的热量。Microsoft 是第一家在生产环境中运行两相浸没式冷却的云提供商。
一直以来，游戏玩家使用超频cpu和水冷却技术来提高台式机的性能。同样的方法能创造更强大的云计算平台吗?
Gamers have long used the combination of overclocking CPUs and water cooling to squeeze peak performance out of PCs. Can that same approach create more powerful cloud computing platforms?
微软的一项新研究表明，这是可能的。该公司在测试浸没式液冷方案时候，尝试让处理器运行在超频状态，可以让服务器的算力水平进一步提高。
New research from Microsoft suggests that it might. The company has been test-driving the use of overclocked processors running in immersion cooling tanks, and says the combination allows servers to perform at a higher level.
“根据我们的测试，我们发现通过使用液冷技术，一些芯片组性能可以提高20%，”微软数据中心高级开发组的杰出工程师和副总裁Christian Belady说。“这表明，浸没液冷方案不仅可以减少并最终消除数据中心的冷却用水，支持我们的可持续目标，让芯片在更合适的温度下运行，还可以为AI和机器学习提供更高的性能。”
“Based on our tests, we’ve found that for some chipsets, the performance can increase by 20 percent through the use of liquid cooling,” said Christian Belady, distinguished engineer and vice president of Microsoft’s datacenter advanced development group. “This demonstrates how liquid cooling can be used not only to support our sustainability goals to reduce and eventually eliminate water used for cooling in datacenters, but also generate more performant chips operating at warmer coolant temperatures for advanced AI and ML workloads.”
这一类型的性能改进在云计算大规模应用时效果可能更显著的，并为建立和运营数据中心提供了新的方法。
Those types of performance improvements could be significant when applied at cloud scale, and enable new approaches to how data centers are built and operated.
“Because of the efficiencies in both power and cooling that liquid cooling affords us, it unlocks new potential for data center rack design,” said Belady.
The research was shared as part of Microsoft’s update on its sustainability initiatives, including a plan to slash its data center water usage by 95 percent by 2024. Increased use of liquid cooling is an important component of this effort, as it allows a waterless design. Microsoft will also begin running warmer data centers, raising the set point for server halls to reduce – and possibly eliminate – the company’s reliance on water-intensive evaporative cooling.
超频：耗电更多、发热也更大
Overclocking: More Power, But Also More Heat
In overclocking, CPUs are run at a higher clock rate than designed – in effect, forcing the computer to run faster than it’s supposed to go. Overclocking boosts performance, but also causes components to generate more heat.
这就是浸没式冷却的作用所在。在两相浸没方案中，服务器被浸泡在冷却液中，当芯片产生热量时，冷却液沸腾，从液体变成蒸汽，热量被蒸汽带走。然后蒸汽冷凝成液体再循环，这一切都不需要泵。浸没式液冷可以提供高的电力效率，因为它使用密封罐，不需要像大多数商业数据中心那样使用架空地板或房间级精密空调。
That’s where immersion cooling comes in. In two-phase immersion, servers are submerged in a coolant fluid that boils off as the chips generate heat, removing the heat as it changes from liquid to vapor. The vapor then condenses into liquid for reuse, all without a pump. Immersion cooling can deliver exceptional power efficiency because it uses sealed tanks that don’t require the raised floors or room-level air cooling found in most commercial data centers.
We’ve been tracking Microsoft’s adoption of liquid cooling, and the company is signaling that two-phase immersion cooling will play a much larger role in future data designs.
“Liquid cooling paves the way for more densely-packed servers in smaller spaces, meaning increased capacity per square foot in a datacenter – or the ability to create smaller datacenters in more strategic locations in the future, Belady said. “This adds to the benefits of waterless cooling design.”
今年3月，微软透露，它正在测试比特币挖矿设施使用的冷却技术。在这些设施中，服务器被浸泡在冷却液中，以管理持续上升的热密度。今年4月，该公司在位于华盛顿昆西的数据中心安装了一个由48台服务器组成的机架，采用两相浸没液冷技术。
In March, Microsoft revealed that it was test-driving cooling technology used in bitcoin mining facilities in which servers are dunked in tanks of cooling fluid to manage rising heat densities. In April it placed a single rack of 48 servers using two-phase immersion cooling into production in its data center in Quincy, Washington.
两相浸没液冷技术的极限在哪儿？
More Immersion Cooling on the Horizon?
微软还没有建立完整的浸没式数据中心，但表示已经准备好扩大其使用。
Microsoft isn’t yet building entire data centers of immersion tanks, but says it is ready to expand their use.
该公司表示:“我们的计划是将这种部署扩展到多个液冷柜，以了解如何扩大液体浸泡冷却和维护服务的可靠性。”“我们将根据结果在其他数据中心开发一个更优化的版本。”
“Our plan is to scale this deployment to multiple tanks to understand how to scale liquid immersion cooling and maintain services reliability,” the company said. “Depending on the outcome, we are going to develop a more optimized version of this technology across other datacenters.”
Microsoft isn’t the first company to connect immersion and performance gains, as this has been a driver in the adoption of immersion in cryptocurrency mining. Riot Blockchain says its research found that using immersion with ASIC chips can boost its hash rate by 25 percent, with the potential for larger gains. This week Riot began construction on 200 megawatts of immersion cooling capacity at a new hashing center in Rockdale, Texas.
Roit Blockchain 公司首席执行官Jason Lee表示:“我们预计，到2022年，该公司无需购买额外的ASIC，也能提高算力和生产率。”
“We anticipate observing an increase in the company’s hash rate and productivity through 2022, without having to rely solely on purchasing additional ASICs,” said Jason Lee, CEO of Riot.
Microsoft’s Azure cloud and Office apps require much higher reliability than bitcoin mining, which can be interrupted without knocking global businesses offline. A key motivation for Microsoft is beefing up its cloud for growing adoption of artificial intelligence (AI) and other high-density applications, which pose challenges for data center design and management.
用于人工智能工作负载的功能强大的新硬件正在为每台设备配备更多的计算能力，提高功率密度(服务器和机架或机柜中存储设备所使用的电量)和随之而来的热量。
Powerful new hardware for AI workloads is packing more computing power into each piece of equipment, boosting the power density – the amount of electricity used by servers and storage in a rack or cabinet – and the accompanying heat.
AI hardware also can create high “flux,” in which power use in a rack increases rapidly as hardware commences a new workload, which can be difficult to manage with traditional air cooling. A number of service providers have focused on air-cooled solutions optimized for high-density workloads, but as densities rise past 25 to 30 kW a rack, users increasingly turn to liquid cooling to manage these workloads.
Belady说，液冷方案是“高密场景制冷的一个主要方向。”
Belady says liquid cooling represents “a major step function for managing density.”
“它为更高密度和更节能的数据中心铺平了道路，”Belady说。“我们现在只是高密计算的前期，我们看好这项技术的未来和发展。”
“It paves the way for higher density and more power-efficient data centers,” said Belady. “We’re only at the beginning of that density curve. We’re really bullish on the technology.”
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