I wish Duplicati would add a retention policy that would allow users to set a maximum amount (size) of backups before deleting them. For example, the UI mockup would look something like this:
So if I have a 2TB drive to backup to, then Duplicati would fill it to the brim and only start deleting old versions once it is full.
If I backup to Backblaze B2 (with no size limits), then I could set a custom limit (say, 1000GB or 1.5TB, etc.) below the retention dropdown. Leaving it blank would allow Duplicati to follow the “Keep All Backups” retention policy (since it can’t calculate the total size of B2.)