I suspect in CO2e if performance is the limitation of what you are doing then an SSD is going to be less CO2e emitted because you can do it on fewer devices. However if you are just looking for space and the performance isn't an issue then the HDD will be the less CO2e emitting solution for now.

This i think will change however as more of the grid uses renewable energy, there is nothing instrinsic in the silicon process that must be burning CO2, its all electricity based and while it uses a lot of energy it doesn't require burning fuel like making Iron does (at the moment).

We have been trying to investigate this SSD/HDD lifecycle carbon footprint tradeoff over the past months, albeit limited to a case study of KV-stores so far. The work is getting published at CCGrid2025 which is currently taking place, so the paper should soon be available.

> However if you are just looking for space and the performance isn't an issue then the HDD will be the less CO2e emitting solution for now

Yes, that is what our results showed and this is the "easy" conclusion: if a HDD can handle the load, then it should be used as it will have both lower operational emissions as well as lower embodied emissions. Where it gets more complicated is when you have a load that you could handle with a single SSD but where a few HDD would be needed in parallel to achieve the same performance. In that case, one of the big factors (besides device lifetime and embodied carbon estimates) is the carbon intensity of your operational electricity: if the electricity footprint is low, you can afford the lower operational efficiency of your HDD setup, since the increased energy consumption is less impactful. The reason this is relevant is because this

> This i think will change however as more of the grid uses renewable energy

does not apply equally to all parts of the lifecycle. Hardware manufacturing is expected to decarbonize much slower than the operational part. See also https://dl.acm.org/doi/10.1145/3604930.3605717 (very insightful article in general).

Agree. These were pretty old numbers and are getting irrelevant by the day.

And as I tried to argue: for performance SSD are a no-brainer in all dimensions.

Space vs. cost: you don't have to tell me. We take care for more than a PB in-house. Guess what? Still mostly on HDs.