BackUp with "inverse" increments

[Helmut Jarausch]

Hi,

I'd like to mirror my root file system (e.g.) to a different disk. The  
mirror should always be most recent.
In addition, I'd like to be able to restore my file system to the state  
of one or more backups before
without storing full size snapshots.

The --backup-dir option does most of the work, but what happens if the  
old backup doesn't contain a file
which is part of the current source. How can I restore the old version  
including deletion of files
which didn't exist in the old version?

Many thanks for some hints or pointers,
Helmut