I know it's best practice to leave at least 10% of an SSD unallocated, so it can be used for over provisioning, to help extend the lifetime of the drive.

SD cards have a much shorter lifetime in terms of write cycles, when compared to an SSD, which makes them a poor choice for write intensive applications. I wonder if it was possible to use over provisioning to help mitigate this problem, and extend the lifetime of such cards.

To clarify, I'm asking if there are any current ways of achieving this. I'm not interested if it's theoretically possible, only if it is actually possible with current software or hardware. However, if there is a technical reason that it's not possible, that would be a very good answer.

1 Answer 1


No. Solid state disks (SSD) have active electronics and firmware to handle tasks such as over-provisioning and wear-leveling. Flash media, such as SD cards, CF cards, thumb drives, etc have no such components.

  • Are you sure about that? I have a feeling that "modern" SD cards do have the ability to handle wear levelling at least. Many eMMC parts definitely do.
    – Attie
    Dec 3, 2019 at 0:44
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    @Attie Yes. The SD card spec has NO entry for wear leveling. There are some devices, typically in industrial applications for reliability, where the controller of the SD card (not the SD card itself) keeps an erase count of the blocks, and new data is written to the block with the lowest erase count each time.
    – Keltari
    Dec 3, 2019 at 1:25
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    " Flash media, such as SD cards, CF cards, thumb drives, etc have no such components." -- Then how is the flash translation layer implemented in such devices that you claim have no "active electronics and firmware"?
    – sawdust
    Dec 3, 2019 at 4:44
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    I think you forgot the rest of the quote... "The SD card spec has NO entry for wear leveling. That is completely dependent on the SD manufacturer to handle that if they so choose. We have seen that some likely do, while others very much do not (beware the super cheap knock-off SD cards)."... I think it's a bit of a stretch to state that no SD cards (etc...) have this capability.
    – Attie
    Dec 3, 2019 at 11:16
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    ... PS: I acknowledge that SD Cards have no equivalent to the TRIM command that SATA / SAS / NVMe SSDs have, but this is an additional hint from the OS / filesystem to the storage device... it's not "Wear Levelling", or proof of presence / absence thereof. It isn't required that SSDs support TRIM.
    – Attie
    Dec 3, 2019 at 11:20

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