1) Have a look in the log of Elasticsearch [engineDir]/elasticsearch/logs to see what Elasticsearch is doing. You may need to give Elasticsearch some more memory in [engineDir]/elasticsearch/config/jvm.options.
2) You are able to reindex all Business Data in the Engine Cockpit:
3) You can configure the Elasticsearch data directory in
ivy.yaml with the configuration key
4) It depends on your operating system. See https://www.elastic.co/guide/en/elasticsearch/reference/current/file-descriptors.html. If you are using CentOS you may need to do the following.
shell> vim /etc/security/limits.conf
* soft nofile 65536
* hard nofile 65536
* soft nproc 2048
* hard nproc 4096
* represents all Linux user names