Symphony.

So, my host's MYSQL server is down (as are all my Symphony clients' sites), so right now I'm left to ponder if there would be a way to test for the primary mysql server, then go to a secondary if the connection fails. I'm guessing this would have to be put into the core rather than an extension. Thoughts?

It would have to be part of the core since Extensions rely on being instantiated by the core. /lib/core/class.symphony.php is where the database object is created (and connection established). Perhaps you could do something in there.

However, you're going to have a problem when it comes to keeping both DB's sync'd.

yeah, the syncing...

Really all that I needed to fix my problem was to have another mysql server ready and waiting with a backup of the DB. On the relatively rare occasion of the server going down, it probably would be sufficient to just edit the config.php file to point to the backup DB manually, then deal with managing DB edits/syncing later. Without handling the syncing automatically, I guess it would be kind of risky to automatically reassign the DB.

I think I was just feeling helpess without my mysql.

If you're going to go to that end it would make sense to mirror the entire site to cover all of your hosts failures. Or, find a better host.