by Ken Task.
I think you are taking the wrong approach to this archive server instance. Why aren't you cloning production server to an archive server (site migration really) every year?
Then once the archive server is up and can be accessed, in production server, reset all courses (moosh has a command for that) removing users with role ID 5 (students) from each course. That command could be put into a looping bash shell script that resets only the course ID's in a text document that contains nothing but the course ID's.
I take it that this archive server is for the purpose of records retention ... correct?
How long is that? 5 years? Then you have to have enough space on a server to host 5 archive instances. tld below means top level domain ... like 'mygreat.edu'
Archive instances are named thusly - archive2020-21.tld, archive2021-22.tld, archive2022-23.tld.
Student roles can view but cannot participate. Teacher roles can view but cannot edit. Basically the archive sites are read only.
Me thinks you are having to 'work to work' too much and you will forever have the issue with dup accounts if not restoring to a fresh moodle instance of same version as production.
Maybe you need to ask someone who runs an Edu site about your same size! ![smile]( "smile")
My 2 cents!
'SoS', Ken