Carbon Footprint of Storage in Data Centers: the Impact of Using Ssds for Key-Value Stores

The greenhouse gas emissions of data centers and the question of how to reduce them are a broad problem that has come into focus with the ongoing climate crisis. Yet, the emissions of storage infrastructures specifically are not well understood. Recent work shows that the manufacturing emissions of SSDs are significantly higher than those of HDDs. Also, the energy consumption of high-end SSDs is in general higher than the one of HDDs. This raises the question of whether the performance improvements provided by SSDs over HDDs are enough to also provide an advantage in terms of carbon footprint. In this paper, we analyze the lifecycle carbon footprint of SSDs and HDDs when used as storage devices for Key-Value stores. Considering state-of-the-art Key-Value stores specifically designed to make best use of HDDs or SSDs, we use specialized hardware to measure the power consumption of NVMe SSDs, as well as of the processor and memory to analyze the impact of different Key-Value stores and workloads on power. We conduct an analysis to determine if SSD-based systems outperform HDD-based systems with respect to their carbon footprint. Our results show that in most cases, the high operational energy efficiency of SSDs allow systems based on SSDs to have lower carbon footprint. However, HDD-based solutions should be considered in cases where the full potential of SSDs cannot be exploited and when the carbon intensity of the electricity powering the data center is low.