So, I'd like to start this off by making perfectly clear that I am very inexperienced with Linux (we have CentOS7) and Elasticsearch. I have inherited a complete ElasticSearch, Logstash and Kibana environment and have been asked to upgrade it and start using it for log monitoring.
The servers were 5.6.2-1 and I upgraded them to 5.6.8-1 before doing a rolling upgrade (took me some time figuring out how to do this with Linux) 6.2.2-1. I completed the upgrade using the rolling upgrade instructions on the website.
Now, when I restart the service
systemctl start elasticsearch.service, it shows that the service is started when I go to
systemctl status elasticsearch. If I wait a minute and type the same command it states the status is "failed". Referring to main ERROR Null object returned RollingFile in Appenders. Then "unable to locate appender "rolling " for logger config "root".
I'm not familiar with how to copy and paste the results of a command.
So there you have it. I've upgraded 2 of my three servers in the Elastic cluster and have Logstash and Kibana running on another server (3 Elasticsearch servers and a Logstash/Kibana server. 4 in total). I have suspended moving forward with upgrades until I get a little more insight into how to get the service running without stopping.
Any help would be greatly appreciated.