Each of my index is 12 shards. I was running a 6R6P cluster(2 shards per partition).
I recently scaled it down to 1R1P configuration.
During the scale down, I reduced the replicacount to 0. After this, the cluster remained green for ~5-6 mins and then suddenly turned Red with unassinedinfo
"unassigned_info": {
"allocation_status": "fetching_shard_data",
"details": "node_left[FtEWJRnCSUGc5U0m6ASKDg]",
"reason": "NODE_LEFT"
},
The unassigned shard index[8] is missing all segment files and is completly empty. How could the cluster be green when the only available copy of the shard was empty?
Could I be running into this : https://github.com/elastic/elasticsearch/issues/21719
I'm working with ES5.6