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

[Alberto Luaces]

Hello,

while converting an old Attic repository, and after the first Borg
backup, I noticed that the size of the whole repository was almost
doubled.

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.

I am not particularly worried about this, since I will eventually
prune the old backups, but I wanted to know if I am right, in order to
account enough space for future upgrades of other Attic repositories I
have.

Thanks!

-- 
  Alberto