I have a cluster of 3 nodes where each node has all roles (master, data, ingest).
I use logstash which pushes the data to elasticsearch.
When is the ack sent to logstash? After the data has been replicated or just when it was saved to the ingest node?
Let's say I have node A,B,C. Logstash is sending a bulk index request to A. Is it possible that data is lost, if A crashes after sending the ack to logstash but before the data is replicated to B or C?