I have a brilliantly designed app_offline.htm file that I'd like to display on my site periodically when I'm doing things like backing up the DB. On a server with a real file system, this wouldn't be a problem: I'd just copy app_offline.htm to the my app's root, and IIS will work its magic and redirect all requests to this file.
However, I'm using Azure, so there's no real file system and there's no easy way move files around from one location to another.
How I can I make app_offline.htm play nicely with Azure?
Actually there is a real file system, as each VM instance runs on Windows 2008 Server (SP2 or R2 SP1). To see this for yourself, enable Remote Desktop for your deployment and connect to a running instance.
Knowing this, you should be able to set up a mechanism to perform a file-copy of your app_offline.htm to your app root based on some type of administrative command. You'll just need to make sure each of your web role instances perform this action.