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One option that hasn't been mentioned is tape archives. It's not for everyone, but tapes (LTO) do have a lot of technology and infrastructure behind them that i

One option that hasn't been mentioned is tape archives. It's not for everyone, but tapes (LTO) do have a lot of technology and infrastructure behind them that is built for longevity. In particular, you can do cost-efficient archives to multiple tapes and store them in safe locations. If (and that's a big if) the base cost of the drive is tolerable. There was recently a wonderful post and discussion on LTO for "normal" nerds [1]. [1] https://news.ycombinator.com/item?id=30099540 https://news.ycombinator.com/item?id=30099540

btrettel 5y ago
One thing that keeps me from trying tapes is that they are still magnetic. If there's some sort of local electromagnetic event then I'd prefer to have a backup that can handle that. I keep some backup hard drives in metal boxes, which is probably enough (Faraday cage). However, optical disks can almost certainly survive a major electromagnetic event without special precautions.
- uniqueuid 5y ago
  Interesting. Is a magnetic event more plausible for you than other types of decay? I'd expect physical damage from something like a flooding to be much more likely than some sort of magnetic interference. But that probably depends on the location you live in!
  - wtetzner 5y ago
    I think the idea is just to have different kinds of backups that have different failure modes, to make losing everything at once less likely.
  - btrettel 5y ago
    I don't know how likely some sort of electromagnetic event is. I just figure that if I'm going to diversify my backup strategies then something dissimilar/uncorrelated would probably be a better choice. My data is on magnetic hard drives, SSDs, and optical disks, each of which has different risk profiles. As wtetzner said, it's unlikely that a single event could cause all of these to fail. An EMP attack might take out my magnetic hard drives and SSDs but leave the optical disks unaffected. I've also had a hard drive fail due to impact damage that likely would not affect a SSD. Flooding is not something I've thought about before, but since my backups are located in different geographical areas, I should be covered there. Etc.
- axiolite 5y ago
  > local electromagnetic event then I'd prefer to have a backup that can handle that. First of all, the magnetic gauss needed to flip bits on LTO media is huge. It's not a practical concern unless you're choosing an incredibly inappropriate storage location. Second, why wouldn't you store your tapes in a case or a vault that is magnetically shielded? You probably store your discs in cases, instead of insisting they be naturally durable against rough handling and abrasion.
  - btrettel 5y ago
    > First of all, the magnetic gauss needed to flip bits on LTO media is huge. It's not a practical concern unless you're choosing an incredibly inappropriate storage location. You're right, it does seem huge: https://superuser.com/a/568367/111650 https://superuser.com/a/568367/111650 (Some of the links from this answer are quite interesting.) The issue is that I don't know (and I suspect it's difficult to know or even classified) whether an EMP attack (the main scenario I'm worried about, which can be quite powerful) would be sufficient to cause damage. I don't believe there is a consensus on this though I'd be glad to be proved wrong here. > why wouldn't you store your tapes in a case or a vault that is magnetically shielded? I would; as I said I put some magnetic hard drives in Faraday cages. However, I'm not confident that the Faraday cage would be sufficient. A lot of the discussion online about constructing Faraday cages to protect electronics is speculation. I haven't seen any clear data showing that during an EMP attack magnetic data is protected inside of a Faraday cage, or protected without one.
    - axiolite 5y ago
      > I'm not confident that the Faraday cage would be sufficient. Faraday cages are not intended for that purpose. Magnetic shielding is a well understood concept. What you need is some thickness of ferrous metals. https://en.wikipedia.org/wiki/Electromagnetic_shielding#Magnetic_shielding https://en.wikipedia.org/wiki/Electromagnetic_shielding#Magn... https://web.archive.org/web/20070327130322/https://advancemag.com/needfor.htm https://web.archive.org/web/20070327130322/https://advancema... https://interferencetechnology.com/magnetic-shielding-basics/ https://interferencetechnology.com/magnetic-shielding-basics... It's easy to test the efficacy of magnetic shielding yourself if you have a large, powerful magnet and a CRT monitor handy.
ndiddy 5y ago
IMO the biggest problem with tapes is getting data off of them. The LTO standard only has compatibility for 2 generations back (i.e. an LTO-6 drive can read LTO-5 and LTO-4 tapes, but nothing before then). This means that if you have data you want to store for 30 years, you will also need to factor in the difficulty of finding a working tape drive and a computer that can operate it. With optical media, a new Blu-Ray drive can read a CD-R from the 90s so this is less of an issue.
- uniqueuid 5y ago
  True. But on the flip side, the LTO spec guarantees that this two-generation backwards compatibility will remain for the forseeable future. As the article mentions, it's possible that optical discs will become unpopular and cease to exist completely. With tapes, you're in the same boat as a bucket full of institutions to whom archives are VERY important. That's a big plus!
  - PaulHoule 5y ago
    The supply of new media for LTO hasn't been stable... https://www.theregister.com/2019/05/31/lto_patent_case_hits_lto8_supply/ https://www.theregister.com/2019/05/31/lto_patent_case_hits_...

btrettel 5y ago

One thing that keeps me from trying tapes is that they are still magnetic. If there's some sort of local electromagnetic event then I'd prefer to have a backup that can handle that. I keep some backup hard drives in metal boxes, which is probably enough (Faraday cage). However, optical disks can almost certainly survive a major electromagnetic event without special precautions.

uniqueuid 5y ago
Interesting. Is a magnetic event more plausible for you than other types of decay? I'd expect physical damage from something like a flooding to be much more likely than some sort of magnetic interference. But that probably depends on the location you live in!
- wtetzner 5y ago
  I think the idea is just to have different kinds of backups that have different failure modes, to make losing everything at once less likely.
- btrettel 5y ago
  I don't know how likely some sort of electromagnetic event is. I just figure that if I'm going to diversify my backup strategies then something dissimilar/uncorrelated would probably be a better choice. My data is on magnetic hard drives, SSDs, and optical disks, each of which has different risk profiles. As wtetzner said, it's unlikely that a single event could cause all of these to fail. An EMP attack might take out my magnetic hard drives and SSDs but leave the optical disks unaffected. I've also had a hard drive fail due to impact damage that likely would not affect a SSD. Flooding is not something I've thought about before, but since my backups are located in different geographical areas, I should be covered there. Etc.
axiolite 5y ago
> local electromagnetic event then I'd prefer to have a backup that can handle that. First of all, the magnetic gauss needed to flip bits on LTO media is huge. It's not a practical concern unless you're choosing an incredibly inappropriate storage location. Second, why wouldn't you store your tapes in a case or a vault that is magnetically shielded? You probably store your discs in cases, instead of insisting they be naturally durable against rough handling and abrasion.
- btrettel 5y ago
  > First of all, the magnetic gauss needed to flip bits on LTO media is huge. It's not a practical concern unless you're choosing an incredibly inappropriate storage location. You're right, it does seem huge: https://superuser.com/a/568367/111650 https://superuser.com/a/568367/111650 (Some of the links from this answer are quite interesting.) The issue is that I don't know (and I suspect it's difficult to know or even classified) whether an EMP attack (the main scenario I'm worried about, which can be quite powerful) would be sufficient to cause damage. I don't believe there is a consensus on this though I'd be glad to be proved wrong here. > why wouldn't you store your tapes in a case or a vault that is magnetically shielded? I would; as I said I put some magnetic hard drives in Faraday cages. However, I'm not confident that the Faraday cage would be sufficient. A lot of the discussion online about constructing Faraday cages to protect electronics is speculation. I haven't seen any clear data showing that during an EMP attack magnetic data is protected inside of a Faraday cage, or protected without one.
  - axiolite 5y ago
    > I'm not confident that the Faraday cage would be sufficient. Faraday cages are not intended for that purpose. Magnetic shielding is a well understood concept. What you need is some thickness of ferrous metals. https://en.wikipedia.org/wiki/Electromagnetic_shielding#Magnetic_shielding https://en.wikipedia.org/wiki/Electromagnetic_shielding#Magn... https://web.archive.org/web/20070327130322/https://advancemag.com/needfor.htm https://web.archive.org/web/20070327130322/https://advancema... https://interferencetechnology.com/magnetic-shielding-basics/ https://interferencetechnology.com/magnetic-shielding-basics... It's easy to test the efficacy of magnetic shielding yourself if you have a large, powerful magnet and a CRT monitor handy.

ndiddy 5y ago

IMO the biggest problem with tapes is getting data off of them. The LTO standard only has compatibility for 2 generations back (i.e. an LTO-6 drive can read LTO-5 and LTO-4 tapes, but nothing before then). This means that if you have data you want to store for 30 years, you will also need to factor in the difficulty of finding a working tape drive and a computer that can operate it. With optical media, a new Blu-Ray drive can read a CD-R from the 90s so this is less of an issue.

uniqueuid 5y ago
True. But on the flip side, the LTO spec guarantees that this two-generation backwards compatibility will remain for the forseeable future. As the article mentions, it's possible that optical discs will become unpopular and cease to exist completely. With tapes, you're in the same boat as a bucket full of institutions to whom archives are VERY important. That's a big plus!
- PaulHoule 5y ago
  The supply of new media for LTO hasn't been stable... https://www.theregister.com/2019/05/31/lto_patent_case_hits_lto8_supply/ https://www.theregister.com/2019/05/31/lto_patent_case_hits_...