ha-cluster The OpenAIS Standards Based Cluster Framework is an OSI Certified implementation of the Service Availability Forum Application Interface Specification (AIS). The Application Interface Specification is a software API and policies which are used to develop applications that maintain service during faults. Restarting and failover of applications is also provided for those deploying applications which may not be modified. The OpenAIS software is built to operate as plugins to the Corosync Cluster Engine.