For high availability setups, Business Continuity Manager has two sequencers. Only one sequencer is active at a time, serving lock requests to endpoints and processing incoming SQL statements. The active sequencer tracks the state of all systems and tables.
The other sequencer is on standby and takes over if the active sequencer fails.
For managed routing sessions, all incoming requests must go through the active sequencer to determine the state of the objects the sequencer is accessing.