Re: [Duplicity-talk] How to use duplicity for local backup

[MRob]

On 2020-04-25 10:18, edgar.soldin--- via Duplicity-talk wrote:
> hi MRob,
>
> On 24.04.2020 19:50, MRob via Duplicity-talk wrote:
> > Hello, I want to ask opinion about backup tactic please.
> >
> > I found a backup system that using only rsync to a local server. A few 
> > scripts run on the server that create tree of historical directrories 
> > that are filled with hard links to the main rsync target. I never saw 
> > this but my understand of the benefit:
> > * saving space for historical backups because they only use inodes
> > * simple scheme to use rsync and ln
>
> off-topic but interestingly there is a popular backup strategy like 
> that.
>
> on the backend (where the backups are stored)
> - create mirror/snapshot of the last backup folder (eg. using file
> systems like btrfs, zfs or using 'rsync --link-dest=...' below)
> on the backend or locally
> - run rsync and synchronize the new backend folder
> repeat

The system Im looking at isn't that. It uses:

1. rsync from server to local backup server
2. "cp -l" for making incrementals

> > * But am I correct, to understand if a file *change* then the 
> > historical data is lost so its a shortcoming of the scheme.
>
> not necessarily as rsync by default creates a new file if it detected
> changes in the old one, hence your old hardlinks won't be touched in
> that case

However with "cp -l" can I assume changes are lost?

> > Is this scheme popular?
>
> relatively. i for one use it in some places.
>
> > Is it useful in comparison to local-rsync variation of duplicity?
>
> not comparable to what duplicity does. duplicity creates final volumes
> of backup data that are merely dumped on some backend.
>
> > For example, lower CPU needed because not creating archive files and 
> > encrypting them.
>
> as said. completely different approach. you need eg. a backend that
> you trust your unencrypted data with.

Yes it is local system, trusted. In such case is duplicity not the right 
Tool?

> > Can duplicity have gpg turn off when it is not necessary?
>
> yes. but then you may as well check out thy myriad of backup solutions
> out there. one might be a better fit for you.

The point of my thread. Looking for advice here, please.

Maybe I change "cp -l" to "rsync --list-dest" it will be more CPU and 
space efficent than duplicity without gpg?