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    SubjectRe: XFS: how to NOT null files on fsck?
    Date
    In article <20040712225338.GD23623@taniwha.stupidest.org> you wrote:
    > To be quite honest I've never seen nulls in files that a days old, and
    > I have scripts which checksum (md5) my files (hundreds of gigabytes)
    > which would notice this, so knowing how to reproduce it would be nice.

    I can say, that nulls in files are most common at the end of (sys)log files
    filing up to the next block boundary. I always asumed this is due to the
    fact that the filesize in the metadata was not written but the last
    half-finished block was already linked in the inode structure.

    I have never seen null filled data or config files other than that, but I
    do not have busy servers crashing often on me.

    > Log was being appended, system crashed, you get nulls at the end when
    > rebootd, the logger opens the file append and starts writing stuff,
    > the nulls end up in the middle. Arguably this is expected.

    Yes, and it is normally easy to spot, since the messages after the nulls are
    boot messages.

    > see the nulls. I'm pretty sure for you the nulls are not really
    > on-disk, looking at the raw device you won't see them. They nulls are
    > returns for unwritten extents just as nulls are returned for holes in
    > sparse files.

    ls -s compared with ls -l should make that visible?

    Greetings
    Bernd
    --
    eckes privat - http://www.eckes.org/
    Project Freefire - http://www.freefire.org/
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