On Wed, Mar 22, 2006 at 02:15:58PM +0100, Marco Fretz wrote:
> hello
>
> thanks for your answer
>
> may you explain me the thing with the delta compression?
>
> i want to backup some files incremental over ssh with tar. is that
> possible? and is it possible to sudo the tar process on the remote
> machine?
As pointed out, this is possible. However, as an extra clarification:
Rsync is good at only sending the differences in files. This means rsync
(and, by extension, rdiff-backup) works very well on large files where
little changes.
This is the case for uncompressed tar files - they will differ only in
the files and headers that were actually changed since the last backup.
However, compressed (and, worse, encrypted) tar files are a different
story, as a changed header may cause a 'cascade' effect, changing lots
of bits. In this case, using rsync will amount to a very expensive way
of copying the whole file.
So, if you want to go with rsync-a-tar-file, make sure it is not
compressed or encrypted beforehand. (Though running the rsync protocol
itself over an encrypted link is very, very good idea.)
Joachim
