All the professional archives that I'm aware of use some variant of a personal cloud storage system with redundant backups and constant human maintenance.

Most folks in this thread are suggesting something called M-Disc.

I guess I can try some M-Discs and see if they're still readable in four decades, but anything significant also needs redundant backups and human maintenance.

I can't find m-disc DVDs for sale.

I can find m-disc blu-ray discs for sale.

For archival, blu-ray is obviously preferable. For redundancy and cost, as well as maximal reader compatibility, I'd like the DVD option as well.

Either way, these discs are exponsive. Multiple dollars each, sometimes as high as $10/disc. (Granted, that's for 100 GB discs, so it's only $1/10 GB.)

The 25 GB discs seems to hover in the $3-5/disc ballpark. (Or roughly $1/5 - 8GB)

I dunno what to do with this data for many reasons, not the least of which is that I am still pretty skeptical about m-disc as a format, and I'm having a hard time finding any third party testing to support their longevity claims.

Yesterday I asked "Which storage format is reasonably long lived" and I got a lot of "clay tablet" answers.

I went to bed.

I woke up this morning with even more "Clay Tablet" answers, and a few folks being extra condescending and smug.

So let me revisit this thread some more, so that we can figure out if there's something to be gained here.

I'm asking about digital storage formats that are reasonably long lived.

The word "reasonably" was in the original post, and digital was pretty heavily implied, but not explicitly stated.

So let's re-state the question in clearer terms:

What digital storage format is most likely to last 50 years in cold storage?

Clay tablets aren't a digital storage format.

Paper could be made to store digital material, especially using some kind of optical encoding or punch tape, but the information density is pretty low and it would require specialized equipment to read.

How long does Flash last in cold storage? Would an SD card in a safe deposit box be readable in 20 years (assuming you could find the right adapter?)

Lots of folks have already brought up the idea that it's not just the life span of the media that I need to worry about, but also the lifespan of the equipment that reads the media.

I agree that we'll need both to get by, but I recognize that it's more likely that we'll be able to re-create the interface than it is that the data will be recoverable.

I should also clarify that I'm not really asking about "archival" here, in the traditional sense.

All archives require tending. That's the nature of the animal. Constant work from lots of people, running backups, converting formats, moving data around.

The Internet Archive commits to shifting to modern formats as required. The LoC also does a decent job of this.

What I'm looking for is something available to a consumer that, if left untouched for a decade or two in a junk drawer or a safe deposit box, would still be readable.

A live archive would be preferable, but something long lived in cold storage is better than nothing.

I'm down this rabbit hole because I found some floppy disks that had some family history stuff on them, but one of the disks doesn't read anymore.

I have an index, I know what should be on the disk, so I can be reasonably certain I have other copies. It's fine.

But I wasn't expecting to find some floppy disks in a photo album, you know? Just tucked in the back, with a simple index.

It was a nice surprise to find them and, when one of them was dead, a small disappointment.

These disks are less than 30 years old.

Other photo albums in this set definitely have CDs in them. Those CDs are also definitely decaying, but I've already captured what was on them to the live archive.

@ajroach42 Microfiche. Known 100 and proven 100 year storage. Reader is reproducible easily.

IBM Blackwatch tapes, in theory, have a 30 year shelf life, but that doesn't account for format rot or reader rot.

@gedvondur Microfilm is a good callout.

I should really get an optical film scanner.

@ajroach42 Years ago I wrote and did some research on long term archival strategy.

The poster boy for this at the time was the Canadian primary education system which had a 75 year retention requirement for school records. (don't know if this is still true). The only format that works, long term, and doesn't suffer from file format rot or reader rot is Microfiche. Plus, it's pretty forgiving regarding its storage.

At the time I asked HD manufacturers how long data lasts without the drive on.

@ajroach42 They would *not* under any circumstances, speculate as to how long data would last on a hard drive in a powered down state. Can't blame them.

@gedvondur @ajroach42 high-res QR codes on microfiche would be an interesting way to store data

@shyra @ajroach42 Maybe. But QR codes are a "format" subject to format rot.

The nice thing about microfiche is that you can recreate it with technology from the late 19th and early 20th century and no instructions.

@ajroach42 All other mediums, including optical storage has not been proven and still suffers from the aforementioned format rot and reader rot.

@ajroach42 PROM

@djsundog I was half afraid that this was the answer, and that you would be the one to say it.

@djsundog How big a ROM chip can you get?

@ajroach42 heh, not sure, and it's quite possible that they aren't as durable as I assume, but I'm willing to do some digging today if you'd like

@djsundog I would never ask you to do uncompensated labor to satisfy an idle curiosity (but I half expect one of us will do the research either way.)

@ajroach42 I'm already up to 16mbit (2MB) EPROMs (M27C160-100F1 in DIP-42 package for ~US$7 each)

@ajroach42 there are also some 32mbit (4MB) around but difficult to find stock (life in the "obsolete" bin)

@ajroach42 but I can definitely confirm that the PROMs in my 1983 vintage Kaypro 2 have not lost their data in almost 40 years now, so it feels pretty stable, if not the simplest of backup/archival techniques.

could definitely see putting together a "solid state archival board" with a bunch of EPROM, a microcontroller, and a nice serial-based protocol for archiving/restoring data. hmmmm.

@ajroach42 I was looking into this a while back and found these M Discs. https://en.wikipedia.org/wiki/M-DISC

They are pricey but are supposed to last 1000 years.

@ajroach42 Of course having drives around for reading and writing them might be a concern.

@kelbot A well documented storage format can have it's hardware re-created.

@ajroach42 Stone tablets.

@kelbot That's definitely the storage mechanism that has the longest history.

@kelbot I'm skeptical, especially since they've only existed for 12 years.

@ajroach42 True, I'm not sure how they arrived at 1000 years and why they are confident about that. But as far as first hand proof pretty much everything is unproven beyond 50ish years right?

@kelbot We've been writing programs with paper tape for more than 100 years, and some of those still survive in quality high enough to be copied.

https://en.wikipedia.org/wiki/Jacquard_machine

@kelbot @ajroach42 Accelerated-aging tests. Kinda like those machines in Ikea on display, that simulate a butt sitting on a chair millions of times.

@mdm @kelbot but 1) AA tests indicated that most optical storage would last a really long time, and they were wrong. 2) based on what I'm reading, M-disc didn't actually do super well in AA tests. They did better than most cheap disks, but they were outperformed.

@ajroach42 Sadly, the best answer is probably... "the cloud". Let someone else handle the format, since they'll be doing their own upgrades of equipment/storage medium.

@mdm I guess I could have been clearer with my initial request.

My personal archive is 10+ TB, and I run my own cloud provider keeping multiple redundant copies.

Paying someone else to do that would be cost prohibitive, invasive, and irresponsible.

@ajroach42 @mdm #lifegoals right here

@mdm But I'm not looking, specifically, at mass storage.

I can rotate my data around and keep it alive for as long as I need to, but it comes at a cost of complexity and energy use.

I'm wondering about what options exist for cold storage, and The Cloud definitely ain't cold.

@ajroach42 You might be interested in my chart of this conversation:

https://www.solipsys.co.uk/Chartodon/LongTermStorage.svg

@ajroach42

Sure -- we could all do our own versions of the cloud better and cheaper. But then you're functioning as you're own IT department, and what happens when you're gone?

I could create documentation out the wazoo for how I store things, but my family (or executors of my literary estate) wouldn't be able to do the first thing to restore it. They're not nerds, like me.

@ajroach42 As I saw someone put it very well about cloud storage:

"Don't think of it as offloading these tasks onto someone else. Think of it as pooling your resources with other people who want to archive data, and hiring someone whose sole job is to do it for everyone."

@mdm And depending on that company to still be around in 5 years, and depending on that company to be responsible with your data, and depending on that company to have your best interest at heart.

That's a lot of trust in a public company.

@ajroach42 Trust is always going to be an issue. It's the same with lawyers and life insurance -- pick a company that's been around a long time! (For cloud storage, sadly enough, that means AWS or Azure. Encryption keys handled locally. I wouldn't store anything on the Google cloud even if it was free.)

Also, relevant lyrics for a song dealing with storage, and the future, that's been going through my head during our entire conversation:

https://frontalot.com/lyrics/MC-Frontalot-Lyric-Secrets-From-The-Future.html

@ajroach42 this thread has me planning on sticking my home movies on my Nextcloud instance, aka the "warm storage" solution.

@ajroach42

M-disc for long term archival, and a (or more then one) NAS for convenient storage using zfs sounds like a reasonable setup.

Anything else becomes really expensive really fast.

https://edwardbetts.com/price_per_tb/

If I count it correctly, M-disc is about twice as expensive p/gb as just using a stack of harddrives, but it obviously depends how you want to raid them.

#storage

@ajroach42 redundant human maintenance is actually what we all need.

@ajroach42 I'd go for spinning disks and a fairly sparse maintenance schedule, like copy to new disks every 5 years. You could get away with ten years possibly. Disks get bigger so maintenance becomes easier over time (you copy to less disks), you add redundancy every time you copy (because well stored, almost unused disks probably won't fail before 2 or even three 5y cycles) and they are the cheapest long term storage media.

@galacticstone What machine wrote them?

@galacticstone There's a decent chance they'll still work, but that chance will get smaller as time passes.

Something like http://store.go4retro.com/zoomfloppy/ + a working commodore compatible floppy drive would do it.

@galacticstone If it's something you want to pursue, I can almost guarantee I can find someone local to you to help. Us retro-computer geeks and archivists exist all over.