Use the dmcluster service script, found in /opt/teradata/client/nn.nn/datamover/failover/, to run commands on the failover cluster. Whendmcluster config completes the configuration of the cluster, the following occurs:
- Services are stopped and restarted in active mode on the primary servers
- Secondary components are stopped
- Active components on primary servers are monitored at regular intervals by the monitoring service through an SSH connection making sure services are running
If the active Data Mover daemon, REST service, repository, ActiveMQ, or all agents used by the primary daemon are unavailable, the following occurs:
- A failover sequence is initiated
- The failover sequence stops the Data Mover daemon, REST, agents, ActiveMQ, and bundled DSA (if applicable) on the primary servers and starts these components on the secondary server
When the failover sequence completes, the monitoring service shifts to the secondary monitoring server and begins monitoring the now-active secondary components. If the monitoring service finds a running Data Mover component or process on the secondary server, it automatically stops to prevent two services from being active at the same time.
When the Data Mover cluster is actively running on the secondary servers, the high availability service is limited with the following changes:
- The Data Mover repositories are no longer kept in synchronization, the synchronization service is disabled and the sync monitoring service is not in use.
- No additional failover occurs when the main components are unavailable. The cluster must be manually switched back to bring the cluster back to the original active state.
The dmFailover.log file on the monitor servers provide more information on the failover sequence.