Your instance will only clone new content after you’ve federated with a community. And it’s per community, not per instance.

It will also be generating thumbnails for websites that are linked, and a good chunk of the data requirement goes here.

I can tell you that, on average, my instance consumes about 700MB per day. I could cut that down if I federated with less communities, and I could get it down to 400-500MB per day (probably less) if I blocked my instance from generating thumbnails.

It’s not a lot, but over time it will add up. My instance is pretty new, and I have no idea what pruning options are available yet. I’ve got over a month before I have to worry about storage space at the rate I’m using it.

As for system requirements, as long as you’re not supporting users besides yourself, Lemmy will pretty much run on a potato.

TL;DR

• 400-700MB new data per day depending on your usage habits
• Whatever you want to run it on will probably be fine

EDIT: Turns out ~90% of my Lemmy data is just for debugging and not needed:

https://github.com/LemmyNet/lemmy/issues/3103#issuecomment-1631643416