[lug] directory/image/cd file space usage differences

[D. Stimits]

I won't guarantee my answer, but I strongly suggest you're looking at
filesystem overhead, and block size differences. The trick is if the
file itself is the right size. With really big files, you'll probably
see a bigger effect. This seems to be especially true for journalled
filesystems that might have special schemes.

D. Stimits, stimits at idcomm.com

"qqq1one @yahoo.com" wrote:
> 
> Recently I noticed that I get a slightly lower value
> returned by du when I run it on an image vs the cd the
> image is burned onto vs the directory the image was
> produced from.  What accounts for this?  Example
> below.
> 
> > du -hs burn
> 295M    burn
> 
> > mkisofs -r -o cd_image burn
> <output looks OK>
> 
> > du -hs cd_image
> 293M    cd_image
> 
> > cdrecord -v dev=0,4,0 -blank=fast -data cd_image
> <output looks OK>
> 
> > mount /dev/cdrom
> 
> > du -hs /mnt/cdrom
> 294M    /mnt/cdrom
> 
> > mkdir ~/burn2
> 
> > cp -a /mnt/cdrom1/* burn2
> 
> > du -hs burn2
> 295M    burn2
> 
> > diff -rq /mnt/cdrom1 burn2
> <no differences reported>
> 
> > diff -rq burn burn2
> <no differences reported>
> 
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