> My understanding is that flash memory does not do very well at all for long term unpowered data retention
You need to let flash cells rest before writing again if you want to achieve long retention periods, see section 4 in [1]. The same document says 100 years is expected if you only cycle it once a day, 10k times over 20 years (Fig 8).
You need to let flash cells rest before writing again if you want to achieve long retention periods, see section 4 in [1]. The same document says 100 years is expected if you only cycle it once a day, 10k times over 20 years (Fig 8).
[1]: https://www.infineon.com/dgdl/Infineon-AN217979_Endurance_an...