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    SubjectRe: New filesystem for Linux
    >>> And possibly some broken drives may also return you something that
    >>> they think is good data but really is not (shouldn't happen since
    >>> both disks and cables should be protected by checksums, but hey...
    >>> you can never be absolutely sure especially on very big storages).
    >
    > It happens because
    > - There is limited if any protection on the PCI bus generally
    > - Many PC systems don't have ECC memory, ECC cache
    > - PATA does not CRC protect the command block so if you do enough PATA
    > I/O (eg you are a US national lab ..) you *will* eventually get a bit
    > flip that gives you the wrong sector with no error data. SATA fixes that
    > one.
    > - Murphy is out to get you..

    Should IDE driver read back parameters after writing them before issuing
    the command? That should fix this problem. (except when command is written
    badly)

    > Not seen that, although they do move stuff aorund in their internal
    > block management of bad blocks. I've also seen hardware errors that lead
    > to data being messed up silently.

    I have seen one WD drive bought in 2003 having error in its firmware in
    cache-coherency code --- if you read and write 256 sectors to the same
    places with some pattern repeatedly (with direct IO), it will discard a
    write. It happens only with 256-sector writes, maybe some part of firmware
    treats 256 as 0. Maybe I create testcase sometimes.

    Mikulas

    > Alan
    >
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