If an active system fails unexpectedly, Business Continuity Manager initiates the failover process based on the configured failover mode, and then re-routes the requests to the standby system.
The following failover modes are available in Business Continuity Manager:
| Failover Mode | Description |
|---|---|
| Immediate automatic failover | Business Continuity Manager re-routes all requests to the standby system. When the active system is restored, all requests are automatically routed to the active system. |
| Automatic failover with a delay | Business Continuity Manager waits for a specified time before initiating an automatic failover. This mode prevents brief network outages or Teradata system restarts from causing unnecessary failovers. During the waiting period, the client request is not processed, and the countdown timer waits to failover the system, however the client does not receive any disconnects or errors. If the active system returns to service before the countdown timer expires, the client request is run on the active system without any errors or loss of state. If the active system does not return to service before the countdown timer expires, Business Continuity Manager initiates the automatic failover. |
| Manual failover | An Operator initiates a manual failover to promote the standby system as the new active system. The client request to the active system is interrupted, and the client receives disconnect errors. The Operator promotes the standby system to the new active system, and the former active system becomes the new standby system. Business Continuity Manager routes the client requests to the standby system designated as the new active system. In this mode, the systems do not automatically revert to their previous roles. |
| Manual failover with a delay | Business Continuity Manager uses a countdown timer to automatically promote the standby system to the new active system after a specified time period (typically 12 hours or longer). This mode is recommended for environments without an active Operation team responding to the Business Continuity Manager alerts over an extended period, such as weekends or holidays. |