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Re: OT: Insight into speed of dd seeks and skips



On 19/09/2025 08:07, rhkramer wrote:
I have to read:

https://web.archive.org/web/20140806023041/https://wiki.linaro.org/WorkingGroups/KernelArchived/Projects/FlashCardSurvey

... at least once more -- i'm not sure my approach to writing something in each GB of the card will work as there are a lot of twists and turns that determine where things actually get written.

Concerning low level details of flash memory you may read in addition (mutually linked articles)

<https://lwn.net/Articles/428584/>
Arnd Bergmann. Optimizing Linux with cheap flash drives. 2011

Writing at random blocks (with seed saved somewhere) might help to discover insufficient capacity faster (alternating bunches of writes and reads of some earlier written blocks).

However if probability to face fake capacity is high enough then be ready to discover excessive bitrot rate. Data may be severely damaged after a few months.

The reality is that cost of proper quality control may be comparable to production cost. "Overprice" due to a brand may be reasonable.


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