hi team !! I have set-up 2 clusters with a load balancer !!!! If one server goes down, the other server also goes down? how can we handle this ?

I assume you meant 2 nodes in a single cluster (and not two separate clusters). You need an odd number of nodes to form a stable cluster. So you’d need at least 3 nodes, to make sure that the cluster can tolerate a 1 node failure.