Is it possible to implement such functionality?
It will be similar to “Backup retention: Keep All Backup” but it is not quite that. Backup only each new file in the folder and its changes, but Duplicati should ignore its removal from the folder, but only commit deletion. Thus, files previously backed up but deleted from the original folder are never deleted from the backup, only new and changed old ones are added. After such a backup, you can safely delete files that are not needed at the moment but already saved, and you always know that they are in the archive and will not be deleted from there when deleting files from the folder. In short, Duplicati should only accumulate and replace modified files and to be able to restore all files at once with one command.
- In the “Photos” folder there are 100 photos that are backed up by the above method.
- 90 photos are deleted, 10 photos are changed (Duplicati ignored the deletion of the photos and saved the changed 10 photos in the archive, replacing the old ones in the archive).
- A new 100 photos are added to the Photos folder (Duplicati added them to the archive).
- All photos from the Photos folder are deleted and it becomes empty. (Duplicati ignores deletion but all 200 photos in the archive).
- When restoring, the “Photos” folder in the archive is indicated and all 200 photos are restored with one command to the original “Photos” folder.