On Wed, Sep 1, 2010 at 2:36 AM, Stefan Monnier <[email protected]> wrote: >
> AFAIK the SD cards don't support any kind of "tagged command queuing", > so after writing the first sector in a sequence, the card is supposed to > be in a state where the write is completed (even if power goes out at this > particular moment), so I wonder how they handle this while at the same > time being able to wait for the next write to see if it happens to be > to the next sector. > SD cards support a bulk data transfer or "multiple block write" operation. In this case, it is up to the OS file system driver, device driver and/or SD host controller to buffer contiguous writes, and then stream the buffer to the SD card with a multiple block write operation. For the most efficient writes, you would want your multiple block writes to be aligned with and the size of the erase block in the underlying NAND -- something that the application committing data would need to be aware of.
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