I think it would be a nice feature or app, which allows to automatically save a copy of files on external storage.
On trusted federation instant you could go ahead and sync all user data of all on both servers installed apps, so that the user could login to the other instance and would get the same experience.
A use case would be private Nextcloud servers. One in my place and one in a different place at a friend. Because of the high chance that something on private instances fails. It would double the accessibility and would give a nice backup option for a case, where one location just fails, like fire.
Interesting idea. Some challenges I see:
As soon as one of your users log in to the backup server you could have sync conflicts? How to handle this? Or do you think about a strict one way sync?
Both instances would be accessible with a different URL, so all external links will break.
Having a “backup-all” option is nice. But not sure if keeping a complete second Nextcloud server in sync is the right way. E.g. for my server I do a nightly backup of the database and the data folder which makes it easy to restore the server if something fails.
I think it would be nice that a user has the possibility to backup all his files (including apps). Really nice would be a full backup so that the user can import his data to a new server if he migrates his account.
On a server basis, I don’t really see the need as there are many tested backup programs available.
Nextcloud is a file sync and share solution! Not a backup solution!
There are plenty of great backup solutions out there. In fact I recommend you make regular backups of your nextcloud data and database.
It would be just amazing if Nextcloud could do scheduled encrypted backups of itself to selected federated servers. I don’t think anyone would ever login directly to the backup, rather it would be available as a restore option when installing a new instance.
I agree that Nextcloud is not a backup solution in itself, but a truly federated backup feature would add the benefit of resilience for all.
Most of us have loads of spare disk space that we would be happy to share with our friends.
Perhaps someone can share a backup-script that puts the backup on a webdav-resource (which can be another Nextcloud setup). On Linux you can use davfs to mount webdav resources and then run your backup script.
I do not have a lot of experince with it myself but Duplicity can do backups to webdav