Does Duplicati support selective sync?

Say I have a source folder A containing 1TB+ files on one of my computers, and I have made a full backup of this folder with Duplicati to a remote storage location B. I have another computer where I restored certain files I needed from B into folder C. Now I add some new files to C and want to sync them to B. I’m trying to let B act like a central storage for all my files that I want to backup so that I can retrieve only the files I need on different devices from it, and also upload new or changed files to it. I think to achieve this a full index of all the files should be downloaded and kept synced in each location, instead of the actual files. This is similar to Resilio Sync’s selective sync. But I don’t necessarily need the files to be synced instantly and I really like the idea of Duplicati’s encrypted block storage. Is it possible to do so with Duplicati?

That’s the catch. The index is the local database. This is kept in sync with the backup, but not with other databases on other computers (though you can try – it seems quite risky to do), so the manual cautions:

Creating a new backup job

Never store multiple backups in the same remote location. Backup data files from multiple backup jobs will interfere with each other and will result in failed backup operations. Always create a new remote folder for each backup job that you set up.

Overview

Duplicati is not:

  • A file synchronization program.

If you take a risk and see if you can arrange timings so that no Duplicati is active when you sync latest database between computers using some other tool, in theory when a Duplicati actually gets used, the destination and databases will match, so it should be happy. If conflict arises, the backup may get lost.

You might do better with a sync program, and you can still get versioned backups using Duplicati from either computer. Similarly-named but unrelated program Duplicacy may be able to do your wish better:

Multiple clients to same Backblaze storage is supported, and is exactly what Duplicati says not to do…

EDIT:

Duplicati Direct restore from backup files is the usual way for, say, disaster recovery restore to another computer. It builds a partial temporary database tailored to the restore. One-way full-DB sync probably would be faster than rebuilding the database from backup files constantly, but complex multidirectional sync with backups and restores from many computers seems like it could potentially be very chaotic…

Duplicati is not a sync program. It can restore to a different computer, but you need to plan which is the backup creator and which is the non-creator restore recipient. Backups of different file versions coming from different computers having the same file path will result in the backup holding the latest to backup, assuming you can keep the databases and schedule coordinated between all, and not destroy backups.