Too much info, huh! Overload!
Every journey begins with a small step.
So, start small ... and focus.
Do check resources on destination server - check again after restoring a few courses.
On one of the servers you will be taking backups from ...
Check it's space resource.
In that moode you can set backup preferences for autobackups.
Then set autobackups to run ... but point the backups to go to a designated directory outside of moodledata ... you have to manually create that designated directory. Guess here: /var/www/coursebackups/
Let the auto backup run ... the next day, check /var/www/coursebackups/ ... did all of the courses get backed up?
Now to stage 2 - xfer those to destination server.
How about I stop there ... when you post that Stage 1 has been completed ... will detail Stage 2 - xfer to destination server.
Stage 3 will be restore of those courses.
'SoS', Ken