I have a 5 node, 5.2 cluster currently split over 3 AZs. At the moment, there is no AWS AZ awareness configured. I have two large indices with 5 shards, 1 replica each.
I'm looking to enable awareness, e.g.:
node.attr.aws_zone: eu-west-1b cluster.routing.allocation.awareness.attributes: aws_zone
My question is, how will the shards re-distribute? Will the 5th node (in it's own AZ) get some shards from each index? Is it designed to handle a loss of just one AZ? ...and more of an architectural question, would I be better having just two AZs? Or change the number of nodes? I've always been of the mindset that you should have an odd number in a cluster which doesn't works so well in this scenario.