Mounting an extern HD for borgbackup; Part II

For my further problem with the integration of an external HD under Nextcloud aio I start this thread.
Purely it is before Part. I.
With the help of szaimen I successfully managed to restore a backup. This gave me a clean connection between ncaio and the backup on an external HD.
And because that went so well, I thought about how to improve security by switching two HDs for backups.

So the current HD was removed with umount /dev/sdb1
and the new one mounted with mount /dev/sdb1 /mnt/backup.
Since then I have to read in the log text - even if the original HD is mounted regularly again with control by df -Th:

“Performing backup…Did not find borg.config file in the mastercontainer volume. Cannot create a backup as this is wrong.”

I could now reinstall nextcloud AIO from the borg-backup again. But an answer from you can improve my understanding.

New test from me:
The server was shut down without stopping the container with halt -h. When I restarted, there was no error message even in the nxtcloud and AIO interface. But the previous backups are not recognized.

Hi, you might want to copy the config file from /mnt/backup/borg/config into the mastercontainer volume and name it borg.config which should fix this.

@szaimen, Please tell me the location where the copy should go. I have too little overview of the construction of the master container.
On the one hand, Nextcloud AIO offers a wonderful opportunity for everyday users, but specific things are a little bit tricky.

You might try

sudo cp /mnt/backup/borg/config /var/lib/docker/volumes/nextcloud_aio_mastercontainer/_data/data/borg.config
sudo chmod 777 /var/lib/docker/volumes/nextcloud_aio_mastercontainer/_data/data/borg.config

I think the credentials are not right. How to take them from the existing backup?

This thread reminds me of