low bandwidth problem

[David Kempe]

Hey,
I can't find reference to this anywhere in the archives - please point me in
the right direction if it has been covered before...

I am trying to backup about 1 gb of data over a 56K modem.
Now I have copied a tar ball of that and uploaded it to the backup server
and extracted the data ok so theoretically there should be an out of date
mirror of the data in the target dir for rdiff-backup. When I run
rdiff-backup -v6 /home/PUBLIC/ backupserver.com::/var/backupdisk/location/
it seems to recopy every file again, which is not what I want over a 56K
modem :)

I tried getting rdiff-backup to do this:

 rdiff-backup -v6 /home/PUBLIC/
backupserver.com::/var/backupdisk/location/backup/
then killing it and copying the rdiff-backup-data stuff to
/var/backupdisk/location/ and starting the backup again as above.
however that seemed to not require forcing, (--force) but just copied the
files over again.
I guess I really need to know;
does rdiff-backup overwrite the files that already exist even if it they are
there already?

If it will always do that, how do i get round the problem of low bandwidth -
I can get a mirror of the data on hdd or cd, and the diffs will be fine over
a modem, its just that the first backup is a bit large.

thanks,

David Kempe