Types of Redundancy

I think it is very important to discuss on types of redundancy. There are 3 types of redundancy – Active-Passive, Active-Active and N+1.
Active-Passive :- There are two nodes, One active and other passive. Load keeps on coming to active node. Both nodes monitor each others health (for e.g. using heartbeat). When active fails, passive takes over. Generally an elastic IP is assigned to active which is switched and given to passive when active fails. Very common in database redundancy.

Active-Active :- In this mode, we have both active nodes and a load balancer to balance traffic between either. When one fails other takes over as sole node.

N+1 :- This is a hybrid between above two. We have N machines which are active and 1 passive. When any of the active fails, passive replaces that active.


:+1: :white_check_mark: