[ Thanks to Lee Schlesinger for this link. ]
Today, businesses require high availability (HA) and zero
downtime for many IT services. Redundancy and failover mechanisms
are essential parts of the HA infrastructure. CentOS 6 provides a
reliable, flexible, and powerful clustering solution that lets you
use multiple servers to avoid downtime.CentOS’s sophisticated HA suite provides all the packages you
need for reliable and secure internode communication, including
fencing of failed nodes. It can handle allocating complex resources
and services across multiple nodes, and ensure that if a service
fails, end users don’t see the failure because the service is
either restarted or reallocated to a different node, according to a
predefined scenario.