Overwriting an existing file in a microSD card


I have a SanDisk Extreme 64GB microSDXC card with existing file 150MB size and I have overwritten it many times using the same filename. What will happen to NAND memory cells underneath? Does overwriting the existing data will get your card wear soon? Based on initial search, write/delete/rewrite data will make your card easily get wear but this overwrite scenario of my existing data is like write/rewrite-only case without invoking delete. Thanks!

Overwriting data on a microSDXC card, especially with the same filename, can indeed impact the underlying NAND memory cells.

    • Wear-leveling is a technique used in flash memory (including microSD cards) to distribute write and erase cycles evenly across the storage cells. It helps prevent specific blocks from wearing out faster than others.

Overwriting the same file repeatedly does contribute to wear, but it’s not as severe as constant write/delete/rewrite cycles. However, if you continuously overwrite the same file without invoking any delete operations, the specific blocks associated with that file may experience more wear than others.

Oh I see so it will still contribute to wear and tear. You mentioned about the Wear-leveling technique that will distribute the write and erase cycle of the storage cells. Do you think SanDisk microSD cards such Ultra SDHC and Extreme SDXHC models have such feature?

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While SanDisk doesn’t explicitly mention wear-leveling for all its microSD card models, there’s strong evidence that all modern SanDisk microSD cards, including Ultra SDHC and Extreme SDXHC, have wear-leveling features.

Oh I see, do you think there are indicators to observe that Wear-leveling is functioning with Ultra SDHC and Extreme SDXHC eventhough SanDisk did not explicitly mentioned it?