Re: [gentoo-user] Re: problem formatting new 256 GB USB stick : glances at gparted

[Frank Steinmetzger <Warp_7@gmx.de>]

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Am Thu, Feb 20, 2025 at 11:40:48PM +0100 schrieb Frank Steinmetzger:

> Another thing to consider: don’t put it into the safe for a year without 
> powering it up. As was explained in a previous mail, QLC uses sixteen 
> different levels of charge inside one single flash cell. The chance of a bit 
> flip increases the longer the SSD is powerless and charge slowly (very 
> slowly) dissipates. It’s hard to find exact numbers, and it’s more of a 
> statistical question. Could be a research topic for a slow Sunday. ;-) 
> Also, don’t you live in a hot area?

I knew I’ve seen this data in the past, but couldn’t remeber where and in 
what context. I just stumbled upon the relevant info again.

If you search for "jedec temperature and data retention" you find this PDF:
https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCompatibility%20Mode%5D_0.pdf

It contains establised standard values for flash durability. On slide 28 it 
says:
Client-class SSDs should retain their data w/o power for 1 year if used
8 hours/day at 40 °C and kept at or below 30 °C when off.
There is also a table for other temperatures; the time is cut in half for
5 degrees more.

Mind you, that PDF is 15 years old, TLS had just been released to the public 
one year earlier according to https://en.wikipedia.org/wiki/Multi-level_cell#Triple-level_cell

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