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    SubjectRe: ATA 4 KiB sector issues.
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    On Wed, Mar 10, 2010 at 12:46 AM, Arnd Bergmann <arnd@arndb.de> wrote:
    > On Monday 08 March 2010 04:48:35 Tejun Heo wrote:
    >> Unfortunately, while Windows can assume that newer releases won't
    >> share the hard drive with older releases including Windows XP, Linux
    >> distros can't do that.  There will be many installations where a
    >> modern Linux distros share a hard drive with older releases of
    >> Windows.  At this point, I can't see a silver bullet solution.
    >>
    >> Partitioners maybe should only align partitions which will be used by
    >> Linux and default to the traditional layout for others while allowing
    >> explicit override.  I think Windows XP wouldn't have problem with
    >> differently aligned partitions as long as it doesn't actually use them
    >> but haven't tested it.
    >
    > Any idea if XP can cope with partition tables that use a 32-sector, 128-head
    > geometry rather than the default 63-sector, 255-head one? That seems to
    > be what some flash memory cards are using and it would make any cylinder
    > aligned partition also 4096-byte aligned, at the cost of moving the
    > 1024-cylinder boundary from 7.88 GiB to 2 GiB.
    >
    > Do we know of anything that requires 63s/255h?

    63s/255h is more or less "standard" now.

    Alignment issues can be solved by picking a good multiple of
    _heads_ or _cylinders_:

    For first partition, pick the start at 8th head:

    cyl 0 head 1 sector 1: LBA sector 63) - bad
    cyl 0 head 8 sector 1: LBA sector 8*63) - good (4k aligned)

    For any other partition, pick start cylinder which is a multiple of 8:

    cyl 8*x head 0 sector 1: LBA sector 8*x*255*63 - good (4k aligned)

    This will actually work well for *any* geometry, not only for 63s/255h.
    --
    vda
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