An active-passive configuration is a High Availability configuration that involves two or more nodes and a single Adaptive Server. The node that primarily hosts the Adaptive Server is called the primary nodes; the set of nodes that can potentially host the Adaptive Server are called the secondary nodes.
When the Adaptive Server or any of the resources it depends on, such as disk or the node itself crashes, the Adaptive Server, along with all required resources, is relocated and restarted on a secondary node. This movement from the primary node to the secondary node is called failover.
After failover, the node hosting Adaptive Server is considered the primary node until the system administrator performs planned failover, or until the Adaptive Server on the new primary node fails, causing another failover.
After failover all existing client connections are lost. The
clients must re-establish their connections and resubmit any uncommitted
transactions as soon as the Adaptive Server is started on the secondary
node. The client connection failover can
be done automatically by using HA connections and self-referencing the hafailover entry
in the interfaces file. See “Configuring the interfaces file on the client side” for information.
You can configure the active-passive setup with multiple secondary nodes so that Adaptive Server can survive multiple failures. With a multi-node setup, Adaptive Server is available to service requests from clients as long as at least one of the primary and secondary nodes is available to host the Adaptive Server and its resources. See “Working with a multi node cluster” for more information.
