[Borgbackup] deduplication understanding and best practice?

[tmhikaru at gmail.com]

On Tue, Feb 28, 2017 at 02:29:27PM +0100, Thomas Waldmann wrote:
> >>> i) make a "all in one" linux borg-repository in which I backup
> >>> several PC
> >>> in the aim of benefit of identical blocs deduplication of many PC
> >>
> >> Do this if you have time, but you want to save space (esp. if you have
> >> considerable duplication amongst the machines).
> > 
> > that's not easy to know before
> > but I understand
> > a single repository can save space (If we have considerable duplication
> > ) , but not time
> 
> It's not just "not saving time", it will need quite some additional time
> for chunks cache resync.
> 

Waldmann really isn't kidding here, regenerating the chunks cache can take
quite a lot of time, even on a powerful machine.  Be aware that using a borg
client on a weak cpu with a very large repository on the server will rely
entirely on the *client machine* to do all of the work - resyncing cache,
chunking and compressing the data that needs to be written, you name it.  I
tried this, it just doesn't work well.  If you run into problems where the
client takes a long time to resync one of your computers, or even worse gets
routinely stuck trying to, it'd probably be a good idea to make that
computer have its own repository.

Tim