Editing Flash memory (section)

==== Data retention ====
It is unclear how long data on flash memory will persist under archival conditions (i.e., benign temperature and humidity with infrequent access with or without prophylactic rewrite). Datasheets of Atmel's flash-based "[[ATmega]]" microcontrollers typically promise retention times of 20 years at 85&nbsp;°C (185&nbsp;°F) and 100 years at 25&nbsp;°C (77&nbsp;°F).<ref>{{cite web |title=8-Bit AVR Microcontroller ATmega32A Datasheet Complete |date=2016-02-19 |access-date=2016-05-29 |page=18 |url=https://www.atmel.com/images/atmel-8155-8-bit-microcontroller-avr-atmega32a_datasheet.pdf |quote=Reliability Qualification results show that the projected data retention failure rate is much less than 1 PPM over 20 years at 85&nbsp;°C or 100 years at 25&nbsp;°C |url-status=dead |archive-url=https://web.archive.org/web/20160409120244/http://www.atmel.com/Images/Atmel-8155-8-bit-Microcontroller-AVR-ATmega32A_Datasheet.pdf |archive-date=9 April 2016}}</ref>

The retention span varies among types and models of flash storage. When supplied with power and idle, the charge of the transistors holding the data is routinely refreshed by the [[firmware]] of the flash storage.<ref name="ni12">{{Cite web |date=23 July 2020 |title=Understanding Life Expectancy of Flash Storage |url=https://www.ni.com/en-us/support/documentation/supplemental/12/understanding-life-expectancy-of-flash-storage.html |url-status=live |archive-url=https://web.archive.org/web/20231201202529/https://www.ni.com/en/support/documentation/supplemental/12/understanding-life-expectancy-of-flash-storage.html |archive-date=1 December 2023 |access-date=19 December 2020 |website=www.ni.com }}</ref> The ability to retain data varies among flash storage devices due to differences in firmware, [[data redundancy]], and [[error correction]] algorithms.<ref name="bunnie-microsdcards">{{Cite web |date=29 December 2013 |title=On Hacking MicroSD Cards |url=https://www.bunniestudios.com/blog/?p=3554 |url-status=live |archive-url=https://web.archive.org/web/20231102105433/https://www.bunniestudios.com/blog/?p=3554 |archive-date=2 November 2023 |website=bunnie's blog }}</ref>

An article from [[Carnegie Mellon University|CMU]] in 2015 states "Today's flash devices, which do not require flash refresh, have a typical retention age of 1 year at room temperature." And that retention time decreases exponentially with increasing temperature. The phenomenon can be modeled by the [[Arrhenius equation]].<ref>{{cite web
 |title       = Data Retention in MLC NAND Flash Memory: Characterization, Optimization, and Recovery
 |date        = 2015-01-27
 |access-date  = 2016-04-27
 |page       = 10
 |url         = https://users.ece.cmu.edu/~omutlu/pub/flash-memory-data-retention_hpca15.pdf
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20161007000927/https://users.ece.cmu.edu/~omutlu/pub/flash-memory-data-retention_hpca15.pdf
 |archive-date = 7 October 2016}}</ref><ref>{{cite web
|title = JEDEC SSD Specifications Explained
|url = https://www.jedec.org/sites/default/files/Alvin_Cox%20%5BCompatibility%20Mode%5D_0.pdf
|at = p. 27
}}</ref>