Newbie question: Problem with forgetting/pruning changing subfolders

[Nev]

A clarifying point on terminology:

And restic seems to create a different brach for each snapshot with a different subfolder.

Yes, restic isn’t doing any “branching” at backup time; all sounds fine there. But when it’s time to forget, restic’s auto-grouping isn’t doing what you desire. So manually tell it how you want the snapshots grouped. And run it first with the --dry-run flag to be sure it’ll do what you want.

In the thread referenced above by @arkadi, @fd0 had the pertinent advice:

@fd0

Please be aware that the retention policies applied by restic forget will group snapshots according to the list of directories they contain, so right now you will end up with two groups (for the two lists of dirs). If you don’t want that, you need to tell restic to only group by hostname using --group-by host (the default is --group-by host,paths).