I have successfully to pointing XOOPS to write to sql database on another host. Its not hard, just to change the mainfile.php and add permission to cpanel.

I would like to have XOOPS write to two identical sql databases the same time and when one database is down, the process will continue. Another thing I want to know is if the database will auto sync each other once a downned database is recovered.

xoops doesn't have this kind of functionality yet. If you have control of the db servers you do replication there and transparent to the applications. Not something a cheap hosted server will let you do. If the application was doing the work it would really slow the site down anyway.

I wouldn't suggest doing MySQL connections across an insecure internet. I only recently tried a cpanel system and was suprised it even had the option to open MySQL to the world or any off network device. (Maybe between accounts at the same ISP/net??) Unless it is over an encrypted VPN or isolated network it doesn't sound like a good idea.