What do people use for a shelf-stable backup

Don't use them, but these seem right for you: https://lemm.ee/post/55012343
- Thanks, I missed that post! Looks like the comment section would have answered a lot of my question.
  In the end I have pulled the trigger and bought an M-Disc capable burner and a stack of M-Discs, so I'm gonna give that a go and see how it works out.

Currently the only solution for a consumer are M-Disc Blue rays. They are currently the only "write once read many" media available that are preferable in these types of situations.
The media is comparable cheap - you can safe your amount of data for around 80-90USD/€ initially(or less for more but smaller discs) and then pay around 10$/€ per year for the new amount of data.
The chances that in 20 years someone is still able to read them are fairly high - there are numerous businesses that are using these disc as WORM media to backup important data on a medium that a opposing lawyer later cannot claim "was manipulated". In 50 years it is very likely to be readable at least by professionals. The discs itself are rated for much longer storage.
If you write on them unencrypted there should be no problem of writing on them. Additionally they do not have issues with byte rot,etc.
- Yeah it's an interesting thought. They seem to come up to 100GB capacity, but the wikipedia page claims (with a [dubious] qualifier) that you need some sort of special higher power burning device to write to M-Disc.
  I don't have an optical drive at the moment. Would I just pick any rated for BDXL?
  
  You need a designated M Disc capable burner,yes. (Not generic BDXL,there are slight differences) There are a few on the market though - they cost around 100-150 bucks usually.(In theory you can use a regular writer sometimes - I know people who do that,but why risk that?) I usually recommend the verbatim to my clients,they are dirt cheap and work flawlessly so far.
  For reading the discs any regular data-capabale blue ray disk drive will do.

Just a hdd in usb caddy? IMHO good enough for 4 tier backup.
- Yes this seems to be the general theme. Main issue is sorting out a file system. I can use a self-repairing one, to recover from long term storage issues, but then it likely won't work in Windows which it may need to if I want a layman to be able to access it. So still some refinement of the plan but it's coming together.
  I've also decided to print some physical photos, aiming for 100 per year, and will put everything in a container together. The physical photos are for in case the container is lost for decades and the drives die, then there will at least be something.
  
  If you need something which can withstand some bitrot on single drive, just use par2. As long is filesystem is readable, you can recover files even if bit of data get corrupted

I decided instead to use ZFS. Better protection than just letting something sit there. Your backups are only as good as your restores. So, if you are not testing your restores, those backups may be useless anyway.
ZFS with snapshots, replicated to another ZFS box. The replicated data also stores the snapshots and they are read-only. I have snapshots running every hour.
I have full confidence that my data is safe and recoverable.
With that said, you could always use M-disk.
- ZFS even if only one server is much better than most people have. If your ZFS replication is to a different building you have done pretty good. However as others have pointed out there are limits. Those servers costs you a couple bucks/month in electric (where I live my electric is 100% wind, but most of you should read CO2). You have to buy both servers, and hard drives will crash regularly.
  There are a lot of trade offs, but cold storage backups are often much cheaper in the long run than the backup zfs server. And those cold backups are a lot easier to put into multiple different locations.
- I have automated backups including to cloud, but I want a separated manual system that cannot get erased if I mess something up (accidentally sync a delete, lose encryption key, forget to pay cloud bill). I have 3 2 1 but it's all automated and backups are eventually replaced, if it's not a critical failure I won't necessarily know I've lost something.
  Basically, I specifically want cold storage, and not cloud. I will only add, not delete from it. And I don't want it encrypted.
  Based on other conversations I'm planning on using duel disks mirrored, zfs, annual updates and disk checks with disks rotated out every 5 years (unless failing/failed). Handling the need for layman retrival of data by including instructions with the hard drives.
  
  Basically, I specifically want cold storage, and not cloud. I will only add, not delete from it. And I don't want it encrypted.
  I have a client with a photographic studio. To give you an estimate, his data is around 14TB of mostly camera pictures with approximately 20 years or history and the owner believe it or not, relies on multiple external hard drives for cold storage, he has a 2TB Seagate thats like 2011-2012 old which still works.
  To put in a cupboard tho, M disc is your best bet.
  
  That sounds like a really good idea. You basically get the best of everything.
  The cool thing about ZFS is the pool information is stored on the disks themselves. You can just plug them in and import the pools.

For local backups it depends on what you want to have:
The cheapest option is a usb or thumb drive. But you have to regularly plug it in and copy your backup on it.
The lazy option is to buy a NAS and configure a backup job that regularly creates a backup. Versioned, incremental, differentials and full backups are possible as is WORM to add a bit of extra security. You can configure a NAS to only turn on specified times, do a backup and then turn off again. This will increase protection against encrypting malware. WORM also helps in this case.
Or just let it run 24/7, create backups every hour and install extra services on it like AI powered image analysis to identify people and objects and let it automatically tag your photos. Cool stuff! Check out QNAP and Synology or build a NAS yourself.
A NAS can also be configured to present its content in a LAN by itself. Any computer will automatically connect to it if the access isn't secured by user/password or certificate.
I recommend buying a NAS.
- So, I have a server that has a backup drive, automated backups, and replication to laptops as well as cloud storage in Backblaze B2. What I'm looking for is something completely separated from the automation that is a backup for if I screw up the automation, as well as a backup that a layman can access (i.e. no encryption, media that is usable by anyone). I have had some very bad experiences with flash drives but I am thinking a HDD with SATA->USB cable attached (I already have the cable).
  From the other conversations in this thread mentioning many options, the hard drive option seems the best for my use case, but I've also been convinced of the benefit of printing out some physical photos as well, so my current plan is to get a big container, put a couple of mirrored hard drives in there (to validate against each other as protection against bit-rot), and print 100 photos each year to add to the container to have an extra layer of redundancy.
  
  Printing the photos won't help much. After 20 or so years they are all discolored. You can't prevent that.
  I think SSDs might be the best storage medium for you. Consumer-grade ssds have a 1 year data retention when powered off. That means at least once per year you have to turn it on and copy the data around one time to refresh the cells. This way it'll probably last several 100 years.
  You can't exactly make it fool-proof. Outside people will never know what you did to create your backup and what to do to access it. Who knows if the drives file system or file types are still readable after 20 years? Who knows if SATA and USB connectors are still around after that time?
  For example it is very likely that SATA will disappear within the next 10-15 years as hdds are becoming more and more an enterprise thing and consumers are switching to M.2 ssds.

After reading the previous discussion I think that you should get more than single drive to store cold backups. That way you can at least spread out the risk of single drive failing. 2TB spinning drives are pretty cheap today and if you have, for example, 4 of them, you can buy one now, write your backups to it and in 6 months buy another, write data on that and so on.
This way you'll have drives with year or two difference on purchase date, so it's pretty unlikely all of them fail at once and a single drive gets powered on and checked every other year or so. My personal experience is that spinning drives are pretty stable on the shelf, but I wouldn't rely on them for decades. And of course even with multiple drives you'll still want to replace them every 3-5 years each. Plus with multiple drives, if I were to build setup like that, I'd set up some sort of scripts or other solution where I can just plug the thing in and doubleclick an icon on desktop to refresh the data and maybe get a notification automatically that the drive you're using should be replaced.
And for actual, long term storage, printouts are the way to go. At least in here you can get books made out of photo paper with your pictures. That's one media which is actually stable over long period and using them doesn't require a lot of technical knowledge nor hardware. But I'd still keep digital copies around, as the printouts aren't resistant to things like house fire or water damage.
- Yeah I am thinking of getting a couple of drives and cloning across both. Update both at the same time. I didn't think of getting two drives at different times but that makes sense, thanks for the suggestion!
  I am thinking printouts is a good idea too. I might get a big container, and keep a couple of mirrored drives as well as say 100 photos from each year. Every year I update the drives with additions and then print 100 photos from the previous year to add to the collection.
  
  I personally prefer printed out books of our photos. We are missing quite a few years due to life getting in the way, but the end goal is to have actual books of photos with titles like 'Our family in 2018' and 'Sports of our first born at 2022'. In europe we have a company called 'ifolor' where you can design and order printouts of your photos. They're not really cheap, but the quality is pretty damn good. And their offerings go to pretty decent sized photo albums, up to A3 size and 180 pages (which is over 200€). So, not cheap, but at least so far their quality has been worth the money.
  And they have cheaper options too, but personally I think it's worth the money to get the best quality you can for printouts. And even the smallest and cheapest option is far superior over not having anything at all due to hardware failure or whatever.

I'm using blu-ray disks for the 3rd copy, but I'm not backing up nearly as much data as you are.
The only problem with optical media is that you should only expect it to be readable for a couple of years, best case, at this point and probably not even that as the tier 1 guys all stop making it and you're left with the dregs.
You almost certainly want some sort of tape option, assuming you want long retention periods and are only likely to add incremental changes to a large dataset.
Edit: I know there's longer-life archival optical media, but for what that costs, uh, you want tape if at all possible.
- Same.
  Bought a Blu-ray burner and "archive grade" disks for third location backups.
  I made a list of files that is just a text document (3MB!) that sits on the root of the Blu-ray. There's probably a better way of doing that, but it works for me.
- Hmm I am keen for something that could be left in the cupboard for 50 years and still works when brought out.
  What does it take me to do home tape storage? Do the tapes needs to be stored with climate control or are they pretty stable? Is it feasible for the average person to load the contents?
  I'm thinking of pulling a suitcase out of the cupboard of all the baby photos, but digital files or photo and video.
  
  So, 50 years isn't a reasonable goal unless you have a pretty big budget for this. Essentially no media is likely to survive that long and be readable unless they're stored in a vault, under perfect climate controlled conditions. And even if the media is fine, finding an ancient drive to read a format that no longer exists is not a guaranteed proposition.
  You frankly should be expecting to have to replace everything every couple of years, and maybe more often if your routine tests of the media show it's started rotting.
  Long term archival storage really isn't just a dump it to some media and lock it up and never look at ever again.
  Alternately, you could just make someone else pay for all of this, and shove all of this to something like Glacier and make the media Amazon's problem. (Assuming Amazon is around that long and that nothing catches fire.)
  
  Tape isn't readable by normal people even if they found it tomorrow with a drive already configured to be used.
  In 50 years good luck finding a working drive compatible with LTO4 when LTO32 is out (it's backwards compatible only with previous gen).
  Unless you write on the box "here there are the keys for 100k bitcoins" they'll just trash the tape

This was a recent point of discussion on the 2.5 Admins podcast (https://2.5admins.com/2-5-admins-228/). Some good discussion on there.
My own thought is the best way to handle your family-member-finding-your-old-photos problem is the analog way: make some prints. It’s absolutely idiot proof, the methodology of keeping paper goods is well understood, and the technology is platform independent.
- Having actual prints has always been the consensus among activists. No digital media lasts as long. The media may persist but the technology to read them is long gone.
- Yeah I really want a digital copy, but for redundancy physical photos sounds like a good idea. Maybe I should do the hard drive rotation thing mentioned in other comments, but each year when I'm updating I could print 100 photos as well. Have a suitcase or container where I keep the hard drives and the physical photos. Then I'd have a decent chance of all photos making it in digital form, plus a bunch of photos just in case the hard drives fail. The hardest part will be going back through the previous years finding an printing 100 photos from each year, but after that I don't have to get through too many each year.
  
  A hybrid is probably a good way forward. I had a career as a photographer for a while and I learned from that: going through 1000 photos takes very little time, but going through 10,000 takes an eternity. If you can star or mark your obviously important photos as you go along, it’ll take very little to print them at the end of the year.

Just buy a spinning drive and call it a day. Follow 3-2-1 protocol and you’ll never lose anything . Check your longterm “cold storage” HDD’s 1-2 times a year. They should last 5-10 with little fuss. Some will go longer with no issues.
If you follow 3-2-1 you’ll never lose anything and you only have to spend a few hours a year thinking about backups.
- This is actually terrible advice. WORM media exists for a reason and telling someone with a mere 3-2-1 he will never loose data is absolutely irresponsible.
  Neither is it a good idea to use regular hard-disk for offsite-cold storage. A really really bad idea.
  
  If you follow proper 3-2-1 you are living the four nine’s dude. A “regular” spinning HDD can last a decade or more without fuss (define “regular” please…?)
  You will not lose all 3 backups at once. When one goes down, you replace it. There’s a reason this is industry standard for media production and beyond. “Irresponsible”? Please.
- I have 3 2 1 but I want the equivalent of a suitcase of photos in the cupboard. No family member is gonna be cleaning out my house as they move me to a rest home and stumble upon my Borg backup in B2 object storage. And if they do they won't have the key. I want something a bit closer to physical.
  I think an extra drive for cold storage is a good idea. My main backups are automated, this one I can add any new files done in the last year once a year, then back in the cupboard. I just need to make sure I'm rotating the drives so I don't have the same one in storage for 50 years, and instead buy new ones every 5 years or so.
  
  If this is your fear, why not just have a will or something that specifically describes what to do and where to go?

I have not used them myself, but M-DISC sounds like what you’re looking for. There are a few other alternatives listed on that Wikipedia article, too.
- Thanks, I think the risk here is that there may not be hardware to read it.
  From the suggestions here I'm thinking a hard drive with USB connection would be best. It won't last 50 years but instead I'd replace it every 5 years or so. I'd use an error resistant file system and plug it in each year to add the new files.
  This way I also get the chance to move it to newer technology in future instead of a new hard drive. It would then only need to survive for some period of time after I last replaced it, so there's a good chance of it remaining readable for most of my life.
  
  Thanks, I think the risk here is that there may not be hardware to read it.
  M-Disc DVDs are readable by ordinary DVD drives. So you could simply put a USB DVD drive alongside those backup M-Discs on the shelf.

I usually use a dehydrator for ~3 days on my drives to make them shelf stable. So far I haven’t had any issues.
- This will do nothing at all. Drives don't die by rust. They usually die because the motor somehow can't get the discs to spin. Very often dry lube is the reason. That can occur if you leave the drive off too long.

For photos? Archival prints. As a bonus, you also get a cool album to reminisce later in life.
- I don't want to sort through the 50k photos, and can't print videos. I'm hoping in 10 or 20 years I'll be able to feed it into AI to spit out all the best ones, then I'll consider it.
  We do have photos printed, but only a very small percentage of the total.
  
  Completely understandable. I say this as someone with way more photos in digital only media than I should.

Thinking about this, the only ancient information we are still able to access is painted or edged on stone or clay. How about some sort huge wall with thousands of QRcode like engravings?
- Reminds me of project Silica. Media historically was more durable (stone/ ink and cloth paper, etc) but had a low data density. As density increased, so did fragility
- Haha like
  
  But I'm a millennial so if you think I own a huge amount of land you would be wrong 😛

Tape. Amazon glacier if you're okay with that.
And regular test restores. An untested backup is not a backup.
But when considering what I need to back up, I usually overestimate how much I or other people will care if it's lost. Family photos are great, but what are the odds of someone saying "damn I wish we still had two dozen photos of that one barbecue?"
- I use tape but haven't been happy with my drive for a while, where do you get your drives? (Also OP I wouldn't recommend tape until you cross the 10TB mark personally)
  
  Yeah after looking at the price of a drive, I agree it doesn't seem necessary at the level of data I have.
  
  I don't personally use tape, but I get most of my stuff from eBay. Tape drives are surprising expensive, even LTO-6 is going to run you a few hundred. But you still can't beat the density and longevity.
- I have cloud with B2, I'm looking for cupboard storage that a random family member can pull out and browse through after I get put in a resthome (only half joking).
  Is home tape storage feasible (and good for this use-case)?
  In terms of what to backup, I'm running on the assumption that technology will be able to autofilter the good stuff at some point, no need to put much effort in now haha.

I'm thinking of using a HDD and keeping it at work, which is climate controlled. I'd bring it back every few months to sync the latest.
Since it's constantly being used, I'm pretty confident it'll be usable as a backup if my NAS fails, so it only needs to be "shelf stable" for a few months at a time. If you're retired or something, a safe deposit box at your local bank should do the trick.
- If it's powered off, you'll have no idea when it dies. And they do die just sitting there.
  I've actually had more failures of drives sitting around than ones running constantly.
  
  But I will because it won't work the next time I take it home to sync. The chance that it'll fail during the few months between a sync and an emergency is incredibly low.
  I wouldn't leave it on a shelf for years, just a few months at a time (approximately quarterly).
- I have a cloud backup, so this isn't about a critical loss of data. It's about an accessible copy that isn't encrypted and a layman could get the data off.
  If my house burns down and I lose the copy, I can restore the data from the cloud backup (so long as I'm not in the house when it burns).

For your amount, just an external hard drive attached to a NAS or something is fine, or a 2-bay synology would be more than enough. Drives are coming in 20-24TB models now, that'd keep you going for a long time.
- That's effectively what I have now. However I seem to kill a drive every couple of years, so I am keen for something that can be stored for many years (preferably decades).

The other thing is if I get hit by a bus and no one can work out how to decrypt a backup or whatever.
Documentation, documentation, documentation. No matter what system you have, make sure your loved ones have a detailed, image-heavy, easy to follow guide on how restorations work - at the file level, at the VM level, at whatever level you are using.
That being said, DVDs actually have quite a short shelf life, all things considered. I'd be more inclined to use a pair of archival strength USB NVME drive, updated and tested routinely(quarterly, yearly, whatever makes sense). Or even an LTO tape, if you want to purchase the drive and some tapes.
You can put your backups in something like VeraCrypt. Set an insanely long password, encoded in a QR code, printed on paper. Store it in the same secured location you store your USB drives (or elsewhere, if you have a security posture).
You may also consider, if money is not a concern, a cloud VPS or other online file storage, similarly encrypted. This can provide an easy URL to access for the less tech-savvy, along with secured credentials for recovery efforts. Depending on what your successors might need to access, this could be a very straightforward way to log into a website and download what they need in an emergency.
- As much as I'm worried about family not being able to do it, I'm just as worried that I will do something dumb and lose the encryption key, losing everything. I am keen on the digital equivalent of a suitcase full of photos that could be stumbled upon.
  I also already have borg backup set up to a backup drive and synced to the cloud (Backblaze B2).
  For tape drives, is many thousands of dollars a normal price? Not sure I'm that keen.
  
  If you buy your LTO drive new, then yes they rip you a new one, for sure! Buy it used...but it still will cost you a few hundred. Like I said, if money is not a concern. If losing the encryption key is a concern, then USB is still your best bet. Make two, keep them simple and unencrypted, stick em in two different safes, update them regularly. And print the documentation with pictures!
- archival strength USB NVME drive,
  Does such a thing exist? Ordinary flash storage is pretty bad at keeping its content when powered off for a long time, due to how flash memory works. I'd be curious about such drives.
  
  No, they don't, I pulled it out of my butt. I rewrote my original draft and that slipped in. NVME wouldn't make sense unless you were powering them up every few months for updates.

USB hard drive? If we're talking about a cold backup that's easy to access a USB drive is reliable and easy.
- Yeah based on the suggestions so far this seems like the best option. Just need to make sure I have a way to verify no files are corrupted (and if they are, which ones), and remember to swap it out for a new one every 5 years or so or each time I need a new drive.

I believe M-Disc to be the best consumer grade, optical solution out there. If you want to go commercial grade you are looking for LTO tapes, but your costs begin rising exponentially. If M-Disc claims are to be believed, they should last well longer than your requirement and be able to handle your data footprint using multiple, but not an unreasonable amount of discs.
No matter which solution you choose, if you are targeting multiple decades, you must save not only the media, but ideally the drive, computer and software used to archive. There is no guarantee that any of the existing technology will be relevant or backward compatible across several decades.
- Thanks! I think this is probably a big risk of not being able to find the hardware to play it.
  Through other conversations I think the answer is to instead get a normal drive, USB connection, and every few years replace the drive and copy the data to the new drive, using an error resistant file system and something like rsync that validates that the files arrived correctly.
  As technology changes, I'd move the files as needed onto the more modern media.

In your scenario, I'd be looking at ZFS or BTRFS for your live data, especially when taking photos into account. They'll self-repair files that may run into decay issues, which I've seen a lot of with photos in all formats. Since you already keep off-site backups, I'd then just keep an extra drive around that you snapshot to from time to time.
- So my offsites are an incremental backup, but at some point the oldest version is gone. I am keen for a completely separate, long term snapshot of what I had that could be thrown in a cupboard, and any random family member clearing my house out as I get moved into a rest home at 108 can go through the photos and find a good one to put on my headstone.
  I am also keen for protection against doing something dumb and losing everything (like losing my hard drive and finding out for some reason I can't access my backups because I lost the encryption key because I put it in bitwarden and they shut down years ago and I never moved the key over because I forgot it was stored there).
  
  ZFS and BTRFS both provide that functionality. Have a look into the features.

This is why I do my first-level of backups with rsnapshot. It backs up to the plain filesystem using rsync and uses hard-links to de-dup between backups. No special filesystem, no encryption, restore is just an 'rsync' away.
- Yes my issue is that I seem to be replacing a drive somewhere every couple of years. I am keen for something that can be stored in a cupboard for years, preferably a decent chance at lasting decades.
  
  Ah - I gotcha. That's some terrible luck with drives.

ZFS with automatic snapshots and scrubbing. This will keep as many and as old snapshots as your like. It'll ensure the files don't rot. It'll ensure the media doesn't die, so long as you have enough redundancy and you replace disks as they die. This is what I'd trust for long term storage because I think I understand how and why it works. It should last as long as I feed it disks. If I delete something, I should be able to restore it from a snapshot. The hardware doesn't need to be anything fancy. Just a Pi 4/5 with a couple of WD Elements would be fine. Could add more disks for more redudnancy. I'm running 2-disk residency.
You don't have to touch the software if it's not exposed to the Internet. Whatever works today on it will work 20 years from now, so long as the hardware works. A couple of spare Pis, SD cards and power supplies should let it last for decades.
- I'd rather cold storage but am thinking of looking along these lines, ZFS or btrfs on a standard HDD that I add files on to once a year and replace the disk every few years.
  I have a standard backup setup I just want something that is more point in time and not connected to all the automation, in case I automatically delete everything.
  
  Yup, turn it on, let it do a scrub, then turn it off. I'd still use redudnancy though. Not merely to cover the case of the drive failing, but also to cover the bit rot use case. It's exceedingly unlikely bits to rot at the exact same spot on two or more disks. When ZFS finds a checksum mismatch during a scrub (which indicates bit rot), it'll be able to trivially recover the data from the drive where the checksum matches. It'll then rewrite the rotten part.