Home » Liquid Cooling Moves Upstream to Hyperscale Data Centers
You may have noticed that liquid cooling has had a lot more activity and press coverage this past year. Nonetheless, to many users in the traditional enterprise data center and colocation providers, it still has the reputation of being seen as a niche solution for limited and specialized computing segments, such as high performance computing (HPC) and supercomputing applications. While the thermal transfer effectiveness and energy efficiency of liquid cooling compared to air are well known, enterprise deployments have been relatively limited. Yet, while I am a great proponent of liquid cooling, to be fair, it is not always the best solution for every application. There are still misunderstandings about when and how liquid cooling can be (or even if) it should be implemented in a “conventional” data center environment.
Part of the issue is the relative simplicity and convenience of deploying existing air cooled IT equipment (ITE); just rack and stack servers in a cabinet and you are done. Moves and adds and changes (MAC) are easy, just bring a screwdriver. Everything works fine until your ITE cabinet power density increases beyond 5 kW and thermal issues arise. The dreaded “hot spot” becomes more common, especially since the introduction of blade servers. For example, a classic 10,000 sq ft raised floor facility designed for a 1 MW critical load has an average power density of 100 W/sq ft. When filled with 300 cabinets it represents an average of 3.3 kW per cabinet. In contrast, a typical blade server chassis can draw 4 to 6 kW per 8U to 10 U chassis, trying to install 4 blade chassis results in 16 to 24 kW per cabinet … and you can guess the result. Depending on the age and the design of the data center, this becomes a tactical issue once you start moving past installing a few blade servers here and there. So while you have some leeway by spreading out the higher density ITE cabinets, it becomes more difficult, if not impossible, to cluster them together — which is normally what IT departments want to do with blade servers and SAN storage systems. Even if you use 1U servers which can draw 200 to 500 watts each, 40 servers in a rack represents a similar density issue of 8 to 20 kW per cabinet.