4 ms·

> 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.

> 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.
  - btrettel 5y ago
    Noted, thank you much.
- PaulHoule 5y ago
  The EMP from a nuclear weapon is mostly radio frequency and would be picked up by antennas, power lines and such. (I know an ex-military ham who always unplugs his HF/shortwave radio from the antenna and power when he's not using it because that's what they taught him to do back in the day.) I don't see that kind of EMP erasing magnetic media.

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.
- btrettel 5y ago
  Noted, thank you much.
PaulHoule 5y ago
The EMP from a nuclear weapon is mostly radio frequency and would be picked up by antennas, power lines and such. (I know an ex-military ham who always unplugs his HF/shortwave radio from the antenna and power when he's not using it because that's what they taught him to do back in the day.) I don't see that kind of EMP erasing magnetic media.