If a Teradata Database system is Interrupted, it does not allow sessions to start. All tables on that system are automatically placed in Interrupted state when a Teradata system is placed in Interrupted state.
From Interrupted state, a Teradata system or table can automatically enter a Restore state. Unity periodically attempts to recover a Teradata system or table in the Interrupted state. It can also enter a Restore state if the dispatchers for that system are restarted. To change an Interrupted state to the Restore state, use SYSTEM RECOVER command.
To change to an Unrecoverable state, use SYSTEM DEACTIVATE command.