Another backup question

[Les Mikesell]

On Sun, 2006-03-12 at 06:43, Anne Wilson wrote:
> On Sunday 12 March 2006 10:53, Paul Smith wrote:
> > On 3/12/06, Anne Wilson <cannewilson at tiscali.co.uk> wrote:
> > > Part one - making a script to create the second generation backup onto
> > > diskB - is not a big problem.  What is a bigger problem is what to use
> > > for the second part.  Rsync does not seem to be the right tool for this. 
> > > I don't want all the older stuff copied back onto the workstation, I just
> > > want the new stuff added to the archive.  I'm mainly thinking of a photo
> > > archive.
> >
> > Rsync can be configure in order to copy only the new stuff: option -u.
> >
> Ah, yes.  That brings up another question.  I had always thought that rsync 
> was bi-directional - i.e. it synchronises the source and destination so that 
> they are identical.  Then someone said that it doesn't do that at all, it is 
> uni-directional.  It's a long time since I read the man page - I'll do that 
> today - but any help/guidance/experience would be appreciated.

Rsync only copies in one direction at a time.  You can use the
-u option to only copy newer files, then repeat the other
direction to move updates both ways, but it won't get
deletions and conflicting updates right.  There is a
program called unison that uses state files to track
changes on each system between runs to resolve the
differences.

-- 
  Les Mikesell
   lesmikesell at gmail.com