I have a 8 node elk cluster, 3 data dedicated nodes, 3 master dedicated node and 2 http(kibana) nodes. Currently the indexes are daily created with date stamp. It contains around 21293408 docs on daily average. The indexes are 15 ~ 25 GB. Also currently i have no of shard equals to 1 and replica is 1. I am trying to achieve FT, so in case of two data node failure it can recover smoothly. What will be the no of shards and replica do i need to have ?
Already referred the links.
[Link 1](https://www.elastic.co/elasticon/conf/2016/sf/quantitative-cluster-sizing 2)
Its not giving me a formula or something so that i can achieve FT.