Hot Spares with Virtualmin

I’ve been trying to come up with some way to create a “hot spare” setup where I have a machine that has backups of a server that’s running in another data center that can be popped into production should the main machine go down. From what I understand, the only sure fire way is to rsync server backups to the remote server and restore them. Is this true? I just can’t think of any other way. Also, how should DNS work for a hot spare setup? Should I have just one nameserver entry (IE just that somehow links to both servers’ DNS server, or should I have it setup so that each one has a nameserver entry? (IE and

Thanks in advance

there is some talk about it here:

I tried but haven’t gotten it to work yet
Also trying with the cluster modules to no avail yet