Adaptive Server provides a list of failover addresses to “HA-aware” clients when they connect. This allows high-availability-aware clients or applications to fail over multiple times, whenever the instance to which it is connected becomes unavailable. If the instance has not sent a failover list to the client, the client uses the HAFAILOVER entry information in the interfaces file.
This example allows an HA-aware client to fail over if there is a network failure during login before the instance sends the extended high-availability list:
ase1 query tcp ether blade1 19786ase2 query tcp ether blade2 19786 mycluster query tcp ether blade1 19786 query tcp ether blade2 19786 hafailover mycluster
The HAFAILOVER entry should use the cluster alias as the server name since a client application tries each query line until it establishes a connection to an instance in the cluster. See the Clusters Users Guide for information on how to enable extended high-availability in a cluster environment.
Extended failover requires Open Client 15.0 ESD #3 or later. The client libraries in the Cluster Edition contain ESD #8.
Open Client uses the CS_PROP_EXTENDEDFAILOVER property for extended failover. See the Client-Library/C Reference Manual.
