[Borgbackup] The size of a upgraded Attic repository is almost doubled

[Alberto Luaces]

On Mon, Aug 14, 2017, at 10:17 PM, Thomas Waldmann wrote:
> > while converting an old Attic repository, and after the first Borg
> > backup, I noticed that the size of the whole repository was almost
> > doubled.
> 
> That is expected, search the docs / faq for --chunker-params for an
> explanation.
> 
> > I suspect that what is happening is that Borg is simply storing the
> > old Attic backups, but since new ones use a different algorithm, they
> > cannot share data blocks, thus the increase in size.
> 
> Same algorithm, but different parameters.
> 
> > I am not particularly worried about this, since I will eventually
> > prune the old backups
> 
> Yes. And likely you will want to go that route.
> 
> >, but I wanted to know if I am right, in order to
> > account enough space for future upgrades of other Attic repositories I
> > have.
> 
> You can avoid the repo size doubling by using attic-compatible chunker
> params.
> 
> But that will have a negative impact on resource usage then (and long
> term), so maybe rather don't do that.
> 

Thanks Thomas for your advice; I will follow that route. 

-- 
  Alberto