TIL that SSDs can lose data if left unplugged for long periods of time (only required to hold data up to 1 year), unlike HDDs which as long as the material holds it can take years.

@djlink that is a very poor-quality source; modern SSDs indeed hold data for years, and powering them also doesn't increase data retention; they're not in any technical sense related to static (which needs constant power, very little) or dynamic RAM (which needs refresh cycles every few milliseconds).
You can be pretty certain that a not end-of-write-life SSD will retain data for years to decades. If you care, some SSDs actually specify more than just a overall MTBF (often in the 10⁶ h)

@drahardja they don’t make tech as they used to xD

TIL that SSDs can lose data if left unplugged for long periods of time (only required to hold data up to 1 year), unlike HDDs which as long as the material holds it can take years.

Edit: added link: https://www.slashgear.com/1893447/dont-leave-your-old-ssd-unplugged/

TIL that SSDs can lose data if left unplugged for long periods of time (only required to hold data up to 1 year), unlike HDDs which as long as the material holds it can take years.

Edit: added link: https://www.slashgear.com/1893447/dont-leave-your-old-ssd-unplugged/

@djlink I'm not even sure where the myth that powering on helps data retention comes from; the last thing an SSD would want to do to increase data reliability would be doing any writing in the background.

@djlink IMO the only material proven to hold digital data for decades at this point is tape, as evidenced by the tape reels they keep finding in storage warehouses whose contents are successfully read back https://www.tomshardware.com/software/linux/recovered-unix-v4-tape-quickly-yields-a-usable-operating-system-nostalgia-addicts-can-now-boot-up-unix-v4-in-a-browser-window

I suppose HDDs can hold archival data, but there are way more ways for spinning discs to fail than tape when stored for long periods of time. But maybe we can use magnetic microscopy to recover their data even if their circuits have died, their motors have failed, or their lubricants have died out. https://garnerproducts.com/hubfs/ucsd_recovery_of_partially_degaussed-hdds.pdf

@drahardja @djlink tape storage has its own risks due to the fact it's exposed to the elements. I've heard of cases where audio tape gets mouldy, flaky, sticky, magnetised / demagnetised, disintegrates, unrolls, crinkles, etc.

@mossman @djlink Oh for sure. But given *the same storage conditions* I’ll put my money on tape lasting longer than HDD, SDD, or optical drives.

@djlink that is a very poor-quality source; modern SSDs indeed hold data for years, and powering them also doesn't increase data retention; they're not in any technical sense related to static (which needs constant power, very little) or dynamic RAM (which needs refresh cycles every few milliseconds).
You can be pretty certain that a not end-of-write-life SSD will retain data for years to decades. If you care, some SSDs actually specify more than just a overall MTBF (often in the 10⁶ h)

@djlink on topic: I’ve today plugged in a Compact Flash card that hasn’t been powered in more than 3 years.

Perfect data retention.

Took a quick dd image of it, just in case.

TIL that SSDs can lose data if left unplugged for long periods of time (only required to hold data up to 1 year), unlike HDDs which as long as the material holds it can take years.

Edit: added link: https://www.slashgear.com/1893447/dont-leave-your-old-ssd-unplugged/

@drahardja @djlink I'd imagine you'd need more controlled conditions for tape than the others - they probably don't care so much about temperature, humidity and magnetism. Memory is basically impervious to everything except time and electricity.

@funkylab @djlink
Not powered off they don't.
An HDD can wear out with use but 25 years is easy for storage in a drawer or box in the attic. Floppy storage is far trickier.
Tape needs carefully stored.
Pressed DVDs* and especially pressed CDs are OK, but "written" ones can fade in daylight.

[* Assuming no manufacturing defects]

@raymaccarthy @djlink Ray, I'm sorry, but do you actually understand how flash memory works? powering on the SSD does exactly *nothing* to the cells until you at least read them (in which case you get a slight read wear on the cell and its neighbors), and you won't increase the charge levels inside a cell unless you erase and rewrite it, which does more damage, so the speed of charge leaking is higher than if you've just let the data alone.

(I mean, you're an EE – so model your gate capacitor!

@raymaccarthy @djlink … the charge it holds is your bits (mutliple, because on most SSDs these days you get more than two states); the only way that loses data is by tunneling of charge through the dielectric, which follows a shot noise model. Information-theoretically, we call this a "Z-channel", because you can only get from higher to lower states, never the other way around.
Now, if left alone, a couple of these bits will actually flip – that's why there's extensive forward error correction –

@raymaccarthy @djlink but as long as the number of these high->low state degradations is small enough, that's correctable. Flash memory is already, without long-term storage effects, a lossy medium, which you have to design your error correction for!
So, when an SSD manufacturer designs that error correction (namely, which code to use, and thus how many bits per information word to add as redundancy), they have to design it in such a way that at some erase-write cycle reliability they want to

@raymaccarthy @djlink sell to the customer. But that same redundancy that helps when cells' dielectric layers degrade due to repeated high-voltage "zapping" (right, you apply a high |E| to the cell to implant charge in flash memory!) and doesn't hold charge as well also helps with long-term storage. Just that the effect of "time and temperature", as you can imagine, is a lot smaller than the effect of "make that dielectric experience what would be called a breakdown if it was macroscopic"!
Hence

@digitalstefan @djlink
The highest capacity CF car I have is 1G Byte. It's about x3 the area of the 512G Byte SSD. So the cells could be over 2000x bigger. Likely to be more stable.

I have a 1T micro SD Card in an ex-Chromebook running Linux Mint (64K Flash drive). I don't expect much life from it even powered mostly daily, but the contents are on my server, 2x workstations and a "real" laptop. The 2x workstations and laptop each have SSD and an HDD for user data.

@raymaccarthy @djlink Ray, I'm sorry, but do you actually understand how flash memory works? powering on the SSD does exactly *nothing* to the cells until you at least read them (in which case you get a slight read wear on the cell and its neighbors), and you won't increase the charge levels inside a cell unless you erase and rewrite it, which does more damage, so the speed of charge leaking is higher than if you've just let the data alone.

(I mean, you're an EE – so model your gate capacitor!

@funkylab @djlink
There are no ideal options for SSD. That's why I have backups and the user data on my workstations and main laptop is on HDD (conventional, not shingled or helium etc). The OS is easily installed and restored from backup on a new SSD.
The point is that an unused conventional HDD will last for decades. That's unlikely for SSDs or any high capacity SD card, USB stick etc.