An application is highly available if it survives any single software or hardware failure in the system. Failures that are caused by bugs or data corruption within the application itself are excluded. The following apply to highly available applications:
Recovery is transparent from the applications that use a resource.
Resource access is fully preserved across node failure.
Applications cannot detect that the hosting node has been moved to another node.
Failure of a single node is completely transparent to programs on remaining nodes that use the files, devices, and disk volumes attached to this node.