How to create a superset of an existing back-up repository without re-uploading data?



Hello all - this is my first post here although I’ve been following the forum for a few weeks. I’ve been evaluating Duplicacy on Mac OS X and have decided to adopt it as part of my back-up strategy. With that in mind I’d like to configure it to back up more data, and would like to do this without up-loading the existing data again, if possible.

To make this more concrete, my evaluation has been based on backing up a repository /Users/A to Amazon S3 storage. I’d now like to back up a new repository /Users to the same storage. What’s the best sequence of steps to achieve this so that the existing data for /Users/A (which is probably 90% of /Users anyway) can be re-used as part of the new repository? I have a feeling that Duplicacy’s de-duplication features should make this very easy…

Thanks in advance - Ian


You are correct, this is where duplicacy excels.

Create another repository under /Users with different repository ID but provide the same storage url.

That’s pretty much it. See Init command details for more details.

Relevant quotes from there:

The init command first connects to the storage specified by the storage URL. If the storage has been already been initialized before, it will download the storage configuration (stored in the file named config ) and ignore the options provided in the command line.

The snapshot id is an id used to distinguish different repositories connected to the same storage. Each repository must have a unique snapshot id.


One thing you may want is to ignore the other duplicacy repository files in /Users/A/.duplicacy, by adding that into the filters file.

You would do this so that you don’t backup the duplicacy configuration and cache folder.


@TheBestPessimist, see, this is one of many reasons why we need Honoring com_apple_backup_excludeItem on MacOS

Had this been implemented duplicacy would have marked its folder with the correct metadata and not only skip it itself, but also prevent Time Machine from wasting resources backing up caches – it pays to be a good MacOS citizen :slight_smile:


@saspus, @TheBestPessimist: thank you both for your replies - very helpful.