Difference between migration and failover

Migration is a planned, controlled event that Adaptive Server requests. Failover is an unplanned event that occurs after an Adaptive Server crash or network disconnect.

Applications are not aware of—and you do not need to write code for—migration. However, you must specifically code applications for failover support.

Migration restores the full session context on the new instance. Failover does not; it is up to the application to restore its own context.