I plan to do some maintenance to the server, including updating the server and the server OS, as well as updating Discourse to 2.8.0 from 2.7.x. So I want to set it in to read-only mode for the duration of that process.
I saw the method is oddly in the Backups settings as described:
Firstly, I presume read-only mode does not affect an upgrade process?
Also, it is really weird that Enable read-only is in the Backup settings, and even more weird that it requires restoring to be enabled in order to set the site in to read-only mode. There are other reasons for wanting to set a site in to read-only mode.