I have to ask because my imagination is failing me: what kind of private personal data do you have that is so important that you're worried about it surviving this sort of thing?

Notes and personal source code (private projects, automation scripts, dotfiles...). Not important to anyone but myself :)

Important enough to go through the effort and expense of printing them out and (I'm presuming) scanning them back in?

I mean I guess it just comes down to priorities. I can't think of anything I want to keep so badly I'd bother with that.

I still haven't done it yet, but I plan to do so.

All this important data (the directory I keep my git repos) is less than 90mb in size. With 500kb/page I could store everything in about 180 pages (90 if I print on both sides) which is not that much.

Since I store backup of these git repos in a ZFS dataset, I can do incremental backups (with zfs send -I) every 6 months or so. By my estimates, I would be adding at most 1-2 pages per year.

Also, it is not like I expect to ever need to read that back in. I also keep redundant backups of everything in multiple cloud providers and in external HDs. Using these papers would be a last resort if everything else fails.

Yeah, I guess what I'm saying is: think of the state the world would have to be in for you to lose all your redundant backups except the paper ones.

In that world, would you really want this data back so badly that you're going to scan it all in from a giant pile of paper?

Again, I'm not saying that your data isn't actually that important to you, I'm just personally having a hard time imagining any data is or ever will be that important to me.

> In that world, would you really want this data back so badly that you're going to scan it all in from a giant pile of paper?

I can't answer what I would do if the world was in that state, but I'd rather have the ability to restore my important backup than not.

I might be wrong since I haven't done it yet, but creating the paper backup doesn't seem like a huge time investment.

Cryptocurrency private keys might count.

A solar flare won't destroy anything that isn't plugged into a power outlet. We will also be aware of it days before it hits, time enough to unplug anything and not even need to touch backups.

The disastrous consequences are all in the area of losing the power grid itself.

This is a good reason to backup to a cloud provider on the other side of the planet :).

I remember seeing the 1989 solar storm [1] in upstate New York. I was a little kid and thought aliens had come to Earth. I had never seen such things in the sky before - it was really beautiful.

When the power subsequently went out for two days, my parents got quite tired of me telling them it was an alien invasion.

[1] https://en.wikipedia.org/wiki/March_1989_geomagnetic_storm

Wait, what? You mean there's no way to store data in an external HD that's secure from solar storms under concrete or metal shielding? Or simply keep simultaneous cloud backups on more than one part of the world's surface? You could probably just find a cloud service that offers both shielding and multi-locational backups. For many people, even ordinary people, printing out even their personal data, never mind photos, would be absurdly difficult.

Never seen this before, very interesting!

But how much can one realistically print? 500KB per page isn't much for today's data hoarding standards.

I guess you don't keep images?

500KB/page at $0.02/page = $20.97/GB. HDD is $0.01-0.03/GB, SSD is $0.10-0.25/GB, BD/DVD are $0.02-0.10/GB, respectively, at retail prices and before counting redundancy. $20/GB was as far back for HDD as Oct 1999, which by the way fell further to around $7.50 next year in Oct 2000[1]. Yeah interesting but 10-100 fold density improvement would be nice...

1: https://mkomo.com/cost-per-gigabyte

25G BD-R can be had for 8 ct. However, the patent license royalties are at about 10 ct (I forgot if USD or EUR). Also, you can't retroactively pay the royalties when importing. Patents are bad. They would have developed BluRay without patent protection.

I do have a many GBs of blobs backed up both in external HDs and cloud, but my most important data (which is what I plan to keep redudant copies on paper) is just notes and source code which I keep in small private git repos.

BTW I still haven't backed up anything to paper yet, I bought a laser printer last year to follow that path, but ended up not doing it yet :/

Many years ago, I used to contemplate how much data you could store on a piece of paper with a laser printer. Like a QR code but optimized as much as possible. I only got as far as figuring out how to address a page as a bitmap at full resolution, because I'm not good at algorithms.

I was reading today Wikipedia about Turbo Codes, Viterbi encoding and similar things and it would be interesting to me to read how a very smart person would solve the problem of maximizing data stored on paper with reasonable error correction.

Github recently backed up a lot of open source projects on hardened microfilm and stored it in the Artic. See https://archiveprogram.github.com/

If only there were some other technique to print a large image file onto a page /s

Sure, encryption over image data and printing works fine for retrieving it at a later date.

I was referring to printing the image pixels rather than a serialization of the binary data. A quality printer can do 600dpi in full color - an A4 page can hold a very large image.

Are optical media vulnerable to radiation as well?

normal BR-R shouldn't.

What does BR-R stands for?

Presumably Blu-ray Disc recordable. (More commonly abbreviated to BD-R, rather than BR-R.)

I made a typo. You are very much correct.