Read-only server mode

Hello, as the new admin/grunt/bofh for xwiki.com, i'll have soon to perform some administrative stuff on a running xwiki installation. During past experiences with such database intensive applications, i found out that most of the downtimes can be avoided by simply putting the whole server in read-only mode. I've put up a topic with requirements and implementation notes here : http://www.xwiki.org/xwiki/bin/view/Dev/ReadOnlyServer let me know what are you thoughts. I'm specifically looking for the best idea to appropriately explain users they are running on a read-only server. Thanks in advance, Erwan