We have a cluster with 6 warm data nodes per AZ in EC2, for a total of 18 nodes spread in 3 AZs.
As they were getting full, we added 1 more node to each AZ, and enabled auto-balancing in the cluster.
I expected some of the shards in the 6 nodes in AZ a would move to the new node in AZ a, but instead, I see that some shards from nodes in AZ b are moving to the new node in AZ a.
As moving data across AZs in EC2 incurs in extra costs, I would like to avoid this. Is there an attribute I can set in the nodes to avoid them from rebalancing shards to nodes in other AZs?
Some more info:
- We are currently using ES 6.8
- We have this configuration already set in the data nodes:
cluster.routing.allocation.awareness.attributes' => 'aws_availability_zone'