I'll be the first to admit that this is an area that I don't know a whole lot about.
I'm looking at the multiple dbs plugin and I realize that it uses a primary and a secondary database server. Or at least it's able to do so. Does it do this so it will fallback to the secondary if the first one is not responsive? When the first one comes back, does the data sync up between the two?
Is there any way we can do this and have the secondary server as a perminate resource, never to have anything deleted out of there so there always a record? (That thought is what got me thinking about this.)
We just use a single database setup and run daily backups to a backup server located elsewhere.