Elasticsearch cluster status is Red with unassigned shards

Hi Team,

We use ES 6.4.3 and we see below cluster status

{"cluster_name":"elasticsearch","status":"red","timed_out":false,"number_of_nodes":5,"number_of_data_nodes":2,"active_primary_shards":3150,"active_shards":3161,"relocating_shards":0,"initializing_shards":8,"unassigned_shards":4647,"delayed_unassigned_shards":0,"number_of_pending_tasks":8,"number_of_in_flight_fetch":0,"task_max_waiting_in_queue_millis":45338,"active_shards_percent_as_number":40.44268167860798}

And we see that "unsassigned_shards" is getting reduced over time. However, it is taking too long time. How can we increase the speed of assigning shards?
Will the cluster status turn Green once all unassigned shards are allocated?

Hi!

How did you get to that situation? Upgrading? Restarting? How did you do it?

Maybe this setting helps you:

curl -XPUT localhost:9200/_cluster/settings -d '{
"persistent" : {
"cluster.routing.allocation.node_concurrent_recoveries" : "1"
}
}'

The default value for that setting is '2'.

Hi
I got to this situation by restarting. How will cluster.routing.allocation.node_concurrent_recoveries" : "1" help me? It improves recovery speed?