F5 Load balancer Pool member failover

one virtual server , it has a pool consisting of 2 members ( 2 identical database severs )

the target is : i need when one user is working on one server ( load balancing balanced him to it ) and then this server went down due to monitor on F5 , i need the same session to continue on the second server without the user feel anything .

how can i achieve that ? the servers are configured to sync session with each others & ready for such scenario , but what do i need to enable to my F5 configuration for this target ? i'm using Round Robin as LB method & persistence is by source ip or by cookies