Configure fail-over to hot spare Ubuntu server
I have an application server running on Ubuntu that is accessed via a public URL that is widely known and used by all of my users to get to our service. I have a second, twin server (with its own, unique TCP/IP address, obviously) that is a hot spare for the production server.
What is the best way to fail over from the main server to the hot spare? I cannot wait for DNS servers around the world to update their caches. Should I bring down the main server (which is probably down anyway, or why would I be failing over to the spare), reconfigure the spare with the TCP/IP address on the broken main server, and then reboot the spare?
It seems like there should be a more elegant way.