1.9. Highly Available Applications

Each application has a primary node and up to seven additional nodes that you can use as a backup node, according to the failover policy you define. The primary node is the node on which the application runs when Linux FailSafe is in normal state. When a failure of any highly available resources or highly available application is detected by Linux FailSafe software, all highly available resources in the affected resource group on the failed node are failed over to a different node and the highly available applications on the failed node are stopped. When these operations are complete, the highly available applications are started on the backup node.

All information about highly available applications, including the primary node, components of the resource group, and failover policy for the application and monitoring, is specified when you configure your Linux FailSafe system with the Cluster Manager GUI or with the Cluster Manager CLI. Information on configuring the system is provided in Chapter 5. Monitoring scripts detect the failure of a highly available application.

The Linux FailSafe software provides a framework for making applications highly available services. By writing scripts and configuring the system in accordance with those scripts, you can turn client/server applications into highly available applications. For information, see the Linux FailSafe Programmer's Guide.