By default, you can use isql to connect to an Adaptive Server instance in a shared-disk cluster environment. However, to connect to an Adaptive Server instance in a shared-disk cluster and turn on high-availability failover or extended high-availability failover for the client, you must start isql using the -Q option.
Although isql -Q can use the extended
high-availability capabilities, it is not transparent: when an instance
fails, isql receives an error and you must resubmit
the batch or transaction.
See the Utility Guide.