Re: [BackupPC-devel] [BackupPC-users] improving the deduplication ratio

[Tino S. <bac...@ti...>]

On Wed, Apr 16, 2008 at 02:52:34PM +0200, Ludovic Drolez wrote:

> > > And what about a mix of the two ?
> > > - keep hard links for files less than the chunk size (filenames begin
> > > with an 'f' as before)
> > > - for files bigger than the chunk size, create a regular file which
> > > contains references to the chunks in the cpool (the files could begin
> > > with an 'r' for example).
> > 
> > The main problem is that you cannot tell anymore whether a file(chunk)
> > in the pool is still needed or not. You'd need to look into every backup
> > and check if there's still a reference to that chunk.
> 
> then, instead of the 'r' file containing the references to the chunks,
> simply create a 'r' directory, which will contain hard links to the
> chunks, so that cpool chunks are still referenced as before !

While it would work (and I thought about that myself), I'm not keen on
having even more directories in the BackupPC file system. We're talking
about hundreds of thousands of *additional* files here, if the chunk
size is, say 64k. The File::Rsync stuff would need rewriting though (but
I'm no developer, I'm just guessing).

Tino.

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