
*) when using a backup server then make the backup server engine type
independent from the primary type and dependent on the backup server
hostname.  There is a problem with this in that you may not be able to
automatically backup an msql database to a mysql database and vice versa
if the feature sets for the two engines remain different and you use
features in your applications that are only available with one of the
engines.

*) save update queries for a backup server that is unavailable and send
them to it when it becomes available




