I just concluded a decade long experiment.
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I just concluded a decade long experiment. I had a USB flash drive in a jar buried in my back yard since 2015. I dug it up, plugged it in and it suffered no data loss after 11 years idle underground.
It's a usless experiment but everyone needs hobbies.
It would have been more interstate if you had buried a control USB in a bottle full of water.
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I just concluded a decade long experiment. I had a USB flash drive in a jar buried in my back yard since 2015. I dug it up, plugged it in and it suffered no data loss after 11 years idle underground.
It's a usless experiment but everyone needs hobbies.
@Aaron_DeVries
Size of drive? (Physical AND informational)I have this idea that drives with smaller individual memory cells are more susceptible to leaking.
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@Aaron_DeVries
While doing environmental testing on a helicopter payload, I learned that NVMe drives (and perhaps all SSDs) can write data at high ambient temperatures >40 C, but the data is less permanent than if you write data at normal ambient temperatures.
So on hot days we had to hurry and copy our 4TB drives after the flight because the data had a half-life of a dozen hours or so.That phenomenon is already documented, but I don't think it's widely known.
@swope @Aaron_DeVries the main issue is the Tdelta between active and power off temps. if both are equal you end up with lower retention. Documented in JEP122
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@Aaron_DeVries
While doing environmental testing on a helicopter payload, I learned that NVMe drives (and perhaps all SSDs) can write data at high ambient temperatures >40 C, but the data is less permanent than if you write data at normal ambient temperatures.
So on hot days we had to hurry and copy our 4TB drives after the flight because the data had a half-life of a dozen hours or so.That phenomenon is already documented, but I don't think it's widely known.
@swope @Aaron_DeVries
I should know this and I didn't.
Thank you! -
@Aaron_DeVries
While doing environmental testing on a helicopter payload, I learned that NVMe drives (and perhaps all SSDs) can write data at high ambient temperatures >40 C, but the data is less permanent than if you write data at normal ambient temperatures.
So on hot days we had to hurry and copy our 4TB drives after the flight because the data had a half-life of a dozen hours or so.That phenomenon is already documented, but I don't think it's widely known.
NVMe drives tend to get hot during usage - at least some models do at faster speeds. 40° C is not uncommon and by far not the highest temperature I have seen in working systems.
So what was the NVMe (not ambient) temperature that lead to this outcome? Should have been quite a lot hotter then?
CC: @Aaron_DeVries@mastodon.social
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NVMe drives tend to get hot during usage - at least some models do at faster speeds. 40° C is not uncommon and by far not the highest temperature I have seen in working systems.
So what was the NVMe (not ambient) temperature that lead to this outcome? Should have been quite a lot hotter then?
CC: @Aaron_DeVries@mastodon.social@andi
Sorry I don't have the data available on the case or internal temperatures.I agree that it was probably quite high.
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@andi
Sorry I don't have the data available on the case or internal temperatures.I agree that it was probably quite high.
Breath of relief
. If NVMe drives start loosing data at 40° C - that would be pretty bad!
CC: @Aaron_DeVries@mastodon.social
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@Aaron_DeVries
While doing environmental testing on a helicopter payload, I learned that NVMe drives (and perhaps all SSDs) can write data at high ambient temperatures >40 C, but the data is less permanent than if you write data at normal ambient temperatures.
So on hot days we had to hurry and copy our 4TB drives after the flight because the data had a half-life of a dozen hours or so.That phenomenon is already documented, but I don't think it's widely known.
"@Aaron_DeVries
Mientras realizaba pruebas ambientales en la carga útil de un helicóptero, descubrí que las unidades NVMe (y tal vez todos los SSD) pueden escribir datos a temperaturas ambiente elevadas (>40 °C), pero que dichos datos resultan menos permanentes que si se escribieran a temperaturas ambiente normales.
Por ello, en los días calurosos teníamos que darnos prisa en copiar el contenido de nuestras unidades de 4 TB tras el vuelo, ya que los datos tenían una vida media de unas doce horas, aproximadamente.Este fenómeno ya está documentado, aunque no creo que sea ampliamente conocido."
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@Aaron_DeVries
While doing environmental testing on a helicopter payload, I learned that NVMe drives (and perhaps all SSDs) can write data at high ambient temperatures >40 C, but the data is less permanent than if you write data at normal ambient temperatures.
So on hot days we had to hurry and copy our 4TB drives after the flight because the data had a half-life of a dozen hours or so.That phenomenon is already documented, but I don't think it's widely known.
@swope @Aaron_DeVries huh.. 40 ambient is not that much! People live in climates where it's close to 50 in heatwaves, I haven't heard of anyone losing data to heatwaves…
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@swope @Aaron_DeVries huh.. 40 ambient is not that much! People live in climates where it's close to 50 in heatwaves, I haven't heard of anyone losing data to heatwaves…
That payload was writing continuously about as fast as the drives could go. Not a typical use case I think.
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@swope @Aaron_DeVries the main issue is the Tdelta between active and power off temps. if both are equal you end up with lower retention. Documented in JEP122
@evey @swope @Aaron_DeVries so the storage unit needs to cool down for the bits to properly dry?
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@Aaron_DeVries
I would also like to know.@Aaron_DeVries @swope A lot of physical processes are thermally activated. At higher temperatures the barrier between two (meta)stable states is often easier to cross, which is why things can go wrong at higher temperature.
If it is, as I read it, bits _written_ at higher temperature having a shorter lifetime even at lower temperature after, I can imagine that the state written at higher temp isn’t as far down into the local energy minimum.
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I just concluded a decade long experiment. I had a USB flash drive in a jar buried in my back yard since 2015. I dug it up, plugged it in and it suffered no data loss after 11 years idle underground.
It's a usless experiment but everyone needs hobbies.
Was the flash memory in that USB Drive older SLC type?
In which case I would anticipate that it would have a longer data retention. 11 years is impressive though.
What make and model was that drive?
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@swope @Aaron_DeVries huh.. 40 ambient is not that much! People live in climates where it's close to 50 in heatwaves, I haven't heard of anyone losing data to heatwaves…
@valpackett @swope @Aaron_DeVries I have heard some colloquial stories of "cold"/unpowered backups on flash becoming completely unusable after being stored in a hot safe. it would be interesting to see exactly how sensitive and reliable this effect is
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@Aaron_DeVries @swope A lot of physical processes are thermally activated. At higher temperatures the barrier between two (meta)stable states is often easier to cross, which is why things can go wrong at higher temperature.
If it is, as I read it, bits _written_ at higher temperature having a shorter lifetime even at lower temperature after, I can imagine that the state written at higher temp isn’t as far down into the local energy minimum.
Yes, I imagine that something like that is going on. And the manufacturer is honest about the 35C max operating temperature.
For the user, they write a bunch of data and immediately verify the data are good -- not looking closely at the temperature log. But hours/days later their files become corrupted.
It's something to be aware of, and a curious physics question.
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@evey @swope @Aaron_DeVries so the storage unit needs to cool down for the bits to properly dry?
@job
No, I think it's more like using hot glue on plastic. While it's hot the glue sticks to the plastic, but as it cools your whole crafting project falls apart.(Just a metaphor, not the physics)
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@evey @swope @Aaron_DeVries so the storage unit needs to cool down for the bits to properly dry?
@job @swope @Aaron_DeVries more like the energy difference of the electrons, the hotter they are the easier they migrate. The colder they are the slower they go. Or something like that
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@job @swope @Aaron_DeVries more like the energy difference of the electrons, the hotter they are the easier they migrate. The colder they are the slower they go. Or something like that
I think that's intuitive for storage, but the hot-at-write-time weakness may be a little different.
I'm imagining an array of cups and the drive controller is pouring water in them as the write operation. When the system is hot, the cups are jiggling and aiming the carafe is shaky. Not a lot of water gets in the intended cups, and some spills into the wrong cups. Enough goes in for the theshold of the immediate validity check, though.
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I think that's intuitive for storage, but the hot-at-write-time weakness may be a little different.
I'm imagining an array of cups and the drive controller is pouring water in them as the write operation. When the system is hot, the cups are jiggling and aiming the carafe is shaky. Not a lot of water gets in the intended cups, and some spills into the wrong cups. Enough goes in for the theshold of the immediate validity check, though.
Then even at normal temperature, slow evaporation over days means the amount of water in those cups drops below threshold in enough cups to break ECC margins -- corrupting the files.
I don't have a deep enough understanding of the physics to tell you if that analogy has much validity. But this is my hunch.
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Was the flash memory in that USB Drive older SLC type?
In which case I would anticipate that it would have a longer data retention. 11 years is impressive though.
What make and model was that drive?
I'm unsure if it's SLC or something else, I suspect not as it's an old/cheap 16 gig Lexar USB drive.
