"Cloudron also keeps track of the backups in it's database. The Backup Cleaner checks if entries in the database exist in the storage backend and removes stale entries from the database automatically."

the previous expectation was to remove all on disk which are not in DB, which didn't work. Does it now?

The button isn't mentioned:
https://docs.cloudron.io/backups/#retention-clean-up

Will the task also remove backups from the app-specific backup listings too, or just the overall Cloudron backups? Hopefully app backups too.

Yes, app backups also.

Will it recognize backups if switching between two backup sources at all?

Unfortunately, no. Note that the cleanup itself only happens when you click "cleanup backups" or the nightly cron job. If you somehow avoid the "race" with the cron job, you should be OK...

I think one general issue with Cloudron backup system is that it doesn't have multiple destinations. We don't keep track of previous backup settings (intentionally, for security purposes) but this means that we cannot cleanup old backups properly and cannot restore/clone etc as we ll. I think we will add this soonish. After all the 3-2-1 methodology wants to have 2 backups in different locations which is currently not easily possible.

• Will the task also remove backups from the app-specific backup listings too, or just the overall Cloudron backups? Hopefully app backups too.
• Will it recognize backups if switching between two backup sources at all? For example, let's say I had a backup source #1, then switched to backup source #2 which in-turn removes backups from the list since they are no longer present in backup source #2, but then I switch it back later to backup source #1... will it recognize the backups stored in backup source #1 again? I wonder if this should be extended in a way to not only remove on cleanup task, but recognize on any backup location changes. It's probably a very fringe scenario, but I'm thinking maybe a scenario where one has a backup source used regularly but then maybe once a month or something does a full system backup to another location and flips it back again afterwards.

The bigger feature request of deleting backups from Cloudron itself, I am a bit hesitant. If there is a security issue and some admin's credentials got compromised, I don't want an attacker to be able to delete backups. That will clean out everything, too dangerous.

Right now I am in a situation where I migrated servers and as such the backup method changed just prior, meaning the old backups in my display of backups performed are no longer valid as they do not exist, and I'm unsure how to clear them.

I don't think the retention policy is an cleaning those up either but I suspect because I remember you saying at one point that it keeps previous versions and such as backups for a longer period. Hoping that'll go away on it's own then even if it can't actually delete the files from anywhere since the files no longer exist from 3 weeks back for example.