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....
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