Re: [rdiff-backup-users] Re: Remote encrypted backup with slow connection.

[Dominic Raferd]

Piotr Karbowski wrote:
> On Mon, Sep 21, 2009 at 2:02 PM, Matthew Miller <address@hidden> wrote:
>   
> > On Mon, Sep 21, 2009 at 01:58:11PM +0200, Piotr Karbowski wrote:
> >     
> > > local rdiff-backup dir with remote server but how? If I will use for
> > > example rsync it still need to check whole files for changes (read,
> > > download it) and upload only new. I hope you will understand what I
> > > need and help me.
> > >       
> > rsync won't check whole files unless you give the -c flag. Otherwise, it
> > just compares metadata. I don't know if that's also the case with
> > rdiff-backup, but I assume so.
> >     
>
> So I need to know how rdiff default compares data, if by size and
> mod-time, it will not be so painful but still it will download changed
> files to generate diff.
Rdiff-backup is designed to be ultra-efficient at this activity. It only 
sends the changes in a file over the wire, not the whole file. To do 
this it uses the librsync library which is effectively the same as 
rsync. You can read more about the technique at 
http://en.wikipedia.org/wiki/Rsync. rdiff-backup does not use file times 
to determine whether to do backups. It can backup very large files with 
small changes very quickly.

Dominic