ext3 real disk occupation of a file
Eric Sandeen
sandeen at redhat.com
Tue Aug 18 14:45:47 UTC 2009
Youness HAFFANE wrote:
>
> Hi,
>
> I'm trying to understand why extra blocks are added when you create a
> file in the ext3 fs:
>
> for example, let's create a file of 1111 blocks (4096 bytes for each block)
>
> $ dd if=/dev/zero of=foo bs=4096 count=1111
>
> the real occupation disk is then:
>
> $ du -B 4096 foo
> 1114
>
> instead of 1111
>
> So where the 3 extra blocks come from?
from the indirect blocks. This is how ext2/3 keep track of the layout
of the file.
see http://e2fsprogs.sourceforge.net/ext2intro.html
and in particular the diagram:
http://e2fsprogs.sourceforge.net/ext2-inode.gif
in that paper.
-Eric
> Thanks for help!
>
> youness
>
> --
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