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    SubjectRe: ATA 4 KiB sector issues.
    On 03/08/2010 12:19 PM, Martin K. Petersen wrote:
    >>>>>> "hpa" == H Peter Anvin <> writes:
    > hpa> On the flipside, though, there really is very little net benefit to
    > hpa> 4K as opposed to 512 byte logical sectors: the additional protocol
    > hpa> overhead is relatively minimal, and as long as writes are aligned
    > hpa> full blocks, there shouldn't be any additional overhead on either
    > hpa> the OS or the drive side. On the plus side, you get full
    > hpa> compatibility with the existing software stack. The equation
    > hpa> really seems rather simple.
    > 4KB sectors are not a win for anybody except the drive vendors.

    Obviously. However, larger physical storage unit sizes -- 4K for
    spinning media, but frequently much larger for flash, for example -- is
    already in wide use, and having a huge mishmash of logical block sizes
    isn't going to work very well.

    > There is a push in the industry right now to keep the 512-byte logical
    > blocks forever. The first step would be to report misaligned accesses
    > or accesses that are not a multiple of the physical block size. Second
    > step would be to eventually reject any write that's not a properly
    > aligned multiple of the physical block size.

    I personally suspect that that is the way it is going to go, rather than
    trying to change the software ecosystem to a different logical block
    size. It has been tried in the past and failed, with the sole exception
    of CD-ROMs, pretty much.


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