I'm running a small ElasticSearch cluster (2 data nodes, 1 master node with no data) in which I inject logs with Logstash. I use Kibana 4.0.1.
I got daily indexes with 3 shards and 1 replica.
All was fine until yesterday when I changed an ElasticSearch parameter. I changed index.merge.scheduler.max_thread_count: 1, after having read https://www.elastic.co/guide/en/elasticsearch/guide/current/indexing-performance.html and because my servers use spinning hard disks.
I changed this parameter on my 3 servers and since, Kibana reports the error "Courier Fetch: 33 of 893 shards failed." when I want to see recent logs.
My problem is: I got no errors on my elasticsearch logs so I don't know which indexes fails and can't try to repair them.
Anybody knows how to solve this problem, or how to find which indexes are failing?
(by the way, I removed this new parameter on ES since I got this problem)