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    SubjectRe: Compact Flash Question
    Tomasz Chmielewski wrote:
    >
    > How does it work, then?
    > How can it do wear levelling over the whole CF if some (or most) area
    > of CF is already used by our precious data/metadata?
    > It would have to know the areas where no data is stored, but it
    > contradicts the CF <-> filesystem separation.
    It don't necessarily need to know. It can swap two used blocks, one
    often-used and one
    rarely-used. That way the rarely-used block is rewriten over the
    previously busy
    block, and the busy block is moved to the rarely used area that isn't worn.
    This implies an extra write whenever a busy block is moved. Don't know if
    anybody do this, but the technique is simple enough.

    CF-filesystem separation is necessary, for they can't know in advance what
    filesystem or partitioning scheme will be used. (I have ext3 on CF, for
    example...)

    Helge Hafting




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