Release It!, 2nd Edition

Migratory Virtual IP Addresses

Suppose the server hosting a critical—but not natively clustered—application goes down. The cluster server on its failover node notices the lack of a regular heartbeat from the failed server. This cluster server then decides that the original server has failed. It starts up the application on the secondary server, including mounting any required filesystems. It also takes over the virtual IP address assigned to the clustered network interface.

Unfortunately, the term virtual IP is overloaded. Generally speaking, it means an IP address that is not strictly tied to an Ethernet MAC address. Cluster servers use it to migrate ownership of the address between the members of the cluster. Load balancers use virtual IPs ...