Femtosecond lasers etch data into a very stable medium.
https://arstechnica.com/science/2026/02/microsofts-new-10000-year-data-storage-medium-glass/?utm_brand=arstechnica&utm_social-type=owned&utm_source=mastodon&utm_medium=social
Surprise, onedrive! 
It’s a Microsoft Research project, not a product. There are a lot of challenges to turn it into a product (not least of which is that it requires very high quality optical glass, which makes it more expensive than alternative storage systems).
[ I didn’t work on this project, the team behind it was one floor down ]
@david_chisnall @arstechnica I was tooting half in jest.
This is really awesome technology and even if it does not go anywhere, it is really valuable that people are working on projects like this.
But it does require a trained AI system to read the data. How likely is anyone 10,000 years from now to know exactly what is required?
My opera singer friends would like a word
@arstechnica Are they going to reserve it explicitly for cloud and AI providers?
They're aiming for a new dark ages where we don't have local storage or backup under our own control. It'll all be subject to their inspection and plagiarism.
@arstechnica new?
Here's a 2019 Ars article about the exact same project from Microsoft.
I was thinking that in some #StarTrek original series they stored data in crystals. Maybe the crystals were actually etched glass.
It would be a shame if space aliens came here 10,000 years from now to understand our extinction, and all they could find was data from the Square Kilometer Array.