- Author: Damon Yuan
- Date: 2020-07-21
Say you have a elasticsearch cluster and you want to ensure the highest availability with minimum replicas and shards with fixed node number, how is the relationship between them?
- nodes -> x
- replicas -> y
- shards -> z
If we want to ensure the availability when one of the nodes is down, where min(x) = 2 , then min(y) = 2 and min(z) = 1.
|--- node 1 ---|--- node 2 ---|
|--------------|--------------|
|-- replica 1--|-- replica 2--|
If we want to ensure the availability when two of the nodes are down, where min(x) = 3, then min(y) = 3 and min(z) = 1.