OpenSwitch has a connection monitor (CMON) thread that monitors Adaptive Server and asynchronously notifies threads as soon as connectivity to the remote server is lost.
At the first successful connection attempt to a remote server, OpenSwitch starts a new CMON thread to monitor the state of the remote server. This thread runs as long as the remote server it is monitoring remains online. At the first indication of a remote server failure, the CMON thread notifies all client threads currently connected to the failed server that they (or a server specified by the coordination module) should connect to the next available server in the pool. The busy clients are issued a deadlock error (1205) message and switched immediately to the next server while the idle clients are switched when they attempt to execute their next commands. This failover detection process is always localized to a single connection, and connections are never automatically switched by OpenSwitch without either a switch request or a server down event. If you want all client connections to fail over to the secondary data server at the same time, you can use a coordination module to coordinate the various connections. See the OpenSwitch Coordination Module Reference Manual for complete instructions on creating and using coordination modules.
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