Hi, I need our site to be in a read-only state for when it is in maintenance. The tactic would be as follows:
Put the site in read only mode.
Populate a different folder with the new code.
Upgrade the database and mv the folders so that the new code and DB get live
This is fairly atomic, but not totally, because it will take at least a few seconds to do the last step. So, we need our site to be at least in read-only mode for that time and let users know gracefully. There is a thread started here: https://groups.google.com/forum/#!msg/silverstripe-dev/GD_vcU1SaRI/OU3vNwV0-3YJ
But it seems like it hasn't been followed up on. It seems like a fairly generic problem.