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    SubjectRe: Reiser4. BEST FILESYSTEM EVER.
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    On Sat, 07 Apr 2007 16:11:46 +0200, Krzysztof Halasa said:
    >
    > Gzip - 3 files (zeros only, raw DV data from video camera, x86_64
    > kernel rpm file), 10 MB of data (10*1024*1024),
    > $ l -Ggh zeros dv bin
    > -rw-r--r-- 1 10M Apr 7 15:30 bin
    > -rw-r--r-- 1 10M Apr 7 15:31 dv
    > -rw-r--r-- 1 10M Apr 7 15:31 zeros

    > $ l -Ggh zeros.gz dv.gz bin.gz
    > -rw-r--r-- 1 10K Apr 7 15:31 zeros.gz
    > -rw-r--r-- 1 9.1M Apr 7 15:31 dv.gz
    > -rw-r--r-- 1 9.3M Apr 7 15:30 bin.gz
    >
    > ... and though the numbers may still sound impressive, space savings
    > are less than 10%.

    I am quite sure that the kernel RPM file is *already* compressed, at least
    somewhat. Otherwise, it's hard to explain this:

    -rw-r--r-- 1 529 263 17835757 Apr 5 00:19 kernel-2.6.20-1.3045.fc7.x86_64.rpm

    % du -s /lib/modules/2.6.20-1.3038.fc7/
    76436 /lib/modules/2.6.20-1.3038.fc7/

    and it can't all be slack space at ends of files:

    % find /lib/modules/2.6.20-1.3038.fc7/ -type f | wc -l
    1482

    Even on a 4K filesystem, the *max* wasted slack would be about 4M.

    And what do you know - if you tar.gz that /lib/modules:

    % tar czf /tmp/kern.tar.gz /lib/modules/2.6.20-1.3038.fc7/
    tar: Removing leading `/' from member names
    % ls -l /tmp/kern.tar.gz
    -rw-r--r-- 1 valdis valdis 15506359 2007-04-07 13:19 /tmp/kern.tar.gz

    The *compressed* tar is about 15M (remember the .rpm contained a 2M vmlinuz
    as well - that;s compressed too). So we're right up to the 17M of the .rpm,
    which indicates that the RPM is compressed at a factor close to tar.gz.

    I'd not be surprised to find out that your digital-video also contains
    at least some light compression - if it's mpeg or similar, that's already
    had some *heavy* compression done to it....
    [unhandled content-type:application/pgp-signature]
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