Frank Steinmetzger wrote:
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


-- 
Grüße | Greetings | Salut | Qapla’
Please do not share anything from, with or about me on any social network.

Some are so convinced, they don’t even know anymore of what.


That is confusing.  Data should be OK for one year without power but only if powered 8 hours per day.  Me scratches my head.  Maybe it means should be OK for a year without power and not sure what to think about rest. 

I suspect that things have changed a lot in that time frame despite the confusion.  They may have improved things significantly since then.  Still, if the one year part, less the other part, is accurate then but better now, then my powering up even once a month should be OK.  I only need to worry about if something happens to me and no one touches it for many months, a year or longer. 

I think some maker somewhere needs to repeat these tests and see how things stand now.  Then again, maybe the tech is changing so fast, they can't keep up. 

Time to update my backups again.  :/ 

Dale

:-)  :-)