High Availability Features of the Oracle SQL*Net

From the Oracle client perspective the model is simple, when the server crashes the client sees a broken connection. The client reconnects to the server, and resubmits the transaction. The Oracle SQL*Net provides features and capabilities to incorporate multiple instances running on different hosts under the same service. Hence, when the client reconnects, it is automatically connected through to the surviving instance. The reconnection is not automatic. The client typically incorporates the code to reconnect broken connections (to the same service as before).

With a node or instance failure, the surviving instance(s) must first recover the failed instances state. During this recovery time clients will see a lack of response from the instance. This recovery has nothing do with the Sun Cluster framework. Recovery is totally dependent on Oracle, the transaction volume, and recovery mechanism for OPS.