A Safe Failover Procedure
To safely migrate clients to a standby server without stopping the cluster, follow these steps:
1. If it is not already running, start the standby server using the start-tc-server script. The standby server must already be configured in the Terracotta configuration file.
2. Ensure that the standby server is ready for failover (PASSIVE-STANDBY status). In the Terracotta Management Console (TMC), the status light will be cyan.
3. Shut down the active server using the stop-tc-server script.
NOTE: If the script detects that the mirror server in STANDBY state isn't reachable, it issues a warning and fails to shut down the active server. If failover is not a concern, you can override this behavior with the --force flag.
Clients will connect to the new active server.
4. Restart any clients that fail to reconnect to the new active server within the configured reconnection window.
The previously active server can now rejoin the cluster as a standby server. If restartable mode had been enabled, its data is first removed and then the current data is read in from the now active server.