CoolEdge: hotspot-relievable warm water cooling for energy-efficient edge datacenters

As the computing frontier drifts to the edge, edge datacenters play a crucial role in supporting various real-time applications. Different from cloud datacenters, the requirements of proximity to end-users, high density, and heterogeneity, present new challenges to cool the edge datacenters efficiently. Although warm water cooling has become a promising cooling technique for this infrastructure, the one-size-fits-all cooling control would lower the cooling efficiency considerably because of the severe thermal imbalance across servers, hardware, and even inside one hardware component in an edge datacenter. In this work, we propose CoolEdge, a hotspot-relievable warm water cooling system for improving the cooling efficiency and saving costs of edge datacenters. Specifically, through the elaborate design of water circulations, CoolEdge can dynamically adjust the water temperature and flow rate for each heterogeneous hardware component to eliminate the hardware-level hotspots. By redesigning cold plates, CoolEdge can quickly disperse the chip-level hotspots without manual intervention. We further quantify the power saving achieved by the warm water cooling theoretically, and propose a custom-designed cooling solution to decide an appropriate water temperature and flow rate periodically. Based on a hardware prototype and real-world traces from SURFsara, the evaluation results show that CoolEdge reduces the cooling energy by 81.81% and 71.92%, respectively, compared with conventional and state-of-the-art water cooling systems.