Pushing hard-linked backups

[Matt McCutchen]

On Wed, 2007-11-21 at 14:55 -0500, Eric S. Johansson wrote: 
> Matt McCutchen wrote:
> > On Sun, 2007-11-18 at 17:45 -0500, Eric S. Johansson wrote:
> >> Using some of the techniques you show here, it would be possible to trigger the 
> >> backup process and push the data from the laptop.
> > 
> > Yes, push backups can be done quite elegantly by pushing the new data to
> > a directory and triggering the backup software to pick it up from there
> > with an --rsync-path or post-xfer exec script.  I helped a user set up a
> > push-backup system before (it used rsnapshot and an rsync daemon) and
> > would be happy to help you set one up if you need it.
> 
> I would appreciate that.  Let's try and document the process so that others can 
> benefit from our experience.

OK.  The essential idea is that the laptop pushes its data to a
directory on the backup machine and then triggers the backup machine to
incorporate the data into a hard-linked backup, but you have lots of
flexibility in how to implement this.  If you give me some more
information about your requirements, I can suggest an appropriate setup.
Specifically:

- Are you backing up just your own laptop, or should the setup
accommodate multiple machines?

- Is it a priority to keep the client script simple?

- Does the backup server need to be robust against malicious clients?

- Should the data be encrypted as it passes over the network?

The important decisions are whether to use ssh, a daemon, or some
combination thereof; how to manage the hard-linked backups (I recommend
rsnapshot); and what (if any) security measures to put in place on the
backup server.

Matt