I am trying to understand the behaviour of ES 2.3.4 when replicas are set to 2.
The docs say that "index operations only succeed if a quorum (>replicas/2+1) of active shards are available."
I'm confused by what 'active' and 'available' mean in this context.
On my naive reading, it sounds like an index operation will fail unless all 3 shards are available (1 primary and 2 replicas) because 'quorum' means >replicas/2+1, which in my case means >2, which means 3 must be available.
If one node on my 5 node cluster fails, does that mean that I won't be able to index documents until all shards have 2 replicas available again? That's not really what I was hoping for - I was hoping that by having 2 replicas, I was insulated against a node failing, but it seems that a node failing means all indexing stops until the cluster is fully healed again?
I see that I can also set write consistency to 'one' - will that alter the behaviour of the system if one node fails?