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    SubjectRe: Should raw I/O be added to the kernel?
    Date
    Followup to:  <199901211735.RAA04836@dax.scot.redhat.com>
    By author: "Stephen C. Tweedie" <sct@redhat.com>
    In newsgroup: linux.dev.kernel
    >
    > Yes you can. The way these applications work is to write all of the
    > data for a commit, and to wait for it to complete before finally writing
    > a commit record. That way, provided the OS does not acknowledge the
    > write before it actually reaches the disk, the application can guarantee
    > enough about the write ordering to be sure about data consistency. Raw
    > IO, O_SYNC and fsync() provide enough support for the application to get
    > this right, but fsync() does not provide guaranteed IO error
    > notification so is not sufficient in the presence of errors.
    >

    Actually, it is better than that: as long as the commit record cannot
    pass the data records, you can roll back to a consistent state.

    -hpa
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