Kriorus used to take hard drives with digital data from their clients, and I put a disk there.
But the best strategy is to have many disks in different places: at home, at relatives homes and at other peoples who are interested in digital immortality, as well as buried underground.
Internet Archive also takes personal digital libraries for permanent storage, if they are open to public access.
Both CI and Alcor accept small data storage items (e.g. a DVD / BluRay). But you have to be a member.
Kriorus can also do that, I think.
I have a similar digital mind backup project. No reason to wait for the proper mind uploading if we can already do some data transfer today. And the collected data could also be hugely beneficial for cryonics.
I can also store your data indefensibly, if you agree to store mine. For example, 700 MB.
There are crypto projects that aim to store information permanently (ironic since this post throws a little jab at crypto 😛). Check out arweave for example. I wouldn't put money on them truly being around forever, but it's another avenue if you want some redundancy on top of Alcor.
(This question involves my somewhat bizarre "mind backup" project, that was inspired by Rudy Rucker's "Lifebox" idea.)
Unfortunately, I made some HUGE blunders last year involving my life savings and the market (bonds, though I almost wish it was crypto). It's painful to admit this involved laziness on my part as well as bad judgment.
As a result, my finances are such I can't see a way to pay for both cryonics AND retire.
My question is: could I arrange to mail a hard drive (or future hyper-DVDs) to a company like Alcor after my death, containing all of my "mind backup" data. It's basically hundreds of thousands of disjointed diary entries and diagrams and flowcharts and sketches and lists and preserved records and pics and receipts and instructions and whatnot.
They would then store this media instead of my frozen corpse (which may be disposed of in a pauper's grave or ideally used for medical research).
Obviously, they should charge less to store a small box of disks for five hundred years at room temperature, than an upside-down frozen head in a canister of liquid nitrogen that needs constant topping up.
Once future software has become advanced enough, this data could then be used to make a crude "copy" of my mind; and hey presto, back from the dead.
It's not much, but better than the absolute certainty of oblivion, which is the alternative of doing nothing.
I'm not the only individual this question applies to.
Many users of this site already have huge collections of digital data, which will become MUCH larger before they die.
Some might not want it all to disappear after they're gone.