Oracle OpenStack for Oracle Linux High Availability Guide

A High Availability (HA) cluster is a set of servers (nodes) managed by clusterware to work together for minimizing application downtime as much as possible. Clusterware enables servers to communicate with each other, so that they appear to function as a collective unit. In an active-passive HA cluster, there is one active server running the application, and one or more nodes standing by. If any problem were to occur on the active node that prevents it from running the application, the clusterware is able to detect this problem and start the protected applications on one of the standby nodes. running the application, and one or more nodes standing by. If any problem were to occur on the active node that prevents it from running the application, the clusterware is able to detect this problem and start the protected applications on one of the standby nodes.