I have two servers, each with a physical IP address on a physical network interface:
Server A: 192.168.0.1 (eth0) - PRIMARY Server B: 192.168.0.2 (eth0) - BACKUP
I want to run an application on server A as primary, and the same application on server B as standby. The application is stateless, so I don't need to sync data between the two. The system that sends requests to the application expects to send them to a single IP address. So I need to configure a third IP address:
...that will be bound to Server A. In the event of a fault with the application on Server A, an alarm will be raised, and in response to this I want to execute
ifdown eth0:1 on Server A, and
ifup eth0:1 on Server B, shifting the virtual IP over to the other server, so that it will begin to process requests without having to reconfigure the systems that send the requests.
My question is, how do I configure this on RHEL 4? It's tricky to search for info about this on Google as I'm not entirely sure what this type of config would be called, and "Virtual IP RHEL" just gives a very wide range of topics.