unityadmin> sequencer failover; W Warning: SEQUENCER FAILOVER can cause client connection errors (but transactions will be completed). W READ CAREFULLY! This command should only be executed when you have confirmed the active sequencer on the other unity server has been shutdown or is known to be DOWN. W Do NOT use this command if the WAN between the two unity servers is down, (because the other unity server might still be up and processing connections). W Have you: W 1. Confirmed the other ACTIVE sequencer is DOWN, or other unity server is DOWN? W Or... 2. Halted all systems for a planned failover? Takeover has succeeded. This sequencer is now ACTIVE. unityadmin>
After the connectivity to the failed data center is restored, before allowing the Unity servers to reconnect to each other, make sure the old recovery log on the formerly active Unity sequencer is deleted.
If the connectivity to the failed data center is restored before the sequencer in that data center is reset, it may trigger a split-brain shutdown. Both sequencers must be shut down so an operator can choose an active sequencer. This helps to avoid missed transactions in the recovery log of the now active sequencer. The sequencer roles can be switched later during a planned outage.
Following the failover of the Unity sequencer, the endpoints on the standby Unity server start listening on their primary and standby IP addresses. Clients can then reconnect through this Unity server.