The best computer storage devices that exist today are ephemeral compared to primitive technology such as engraved rocks. A stone tablet can last for millennia, but anything we can store files on will very likely be useless in 50 years. However, there are some prospects for seriously long-lived media in the labs.
Researchers at Berkeley Labs and the University of California at Berkeley have developed a method in which a miniscule iron particle can move within a nanotube under the control of an electric current. The state of the particle can be read without moving it. They estimate a billion years before losing data due to particle drift but don’t discuss whether the physical integrity of the tubes will match.