I have been having issues with the KV Store under 6.2.0 and 6.2.1, mostly in my search head cluster. The first issue I have is that the KV store doesn't always get stopped by a splunk restart, resulting in the mongod process being left running and the KV port bound. This prevents splunk from restarting, which has resulted in a couple of cluster failures/issues. I see an existing unanswered question about this one (http://answers.splunk.com/answers/191451/splunk-62-mongod-does-not-seem-t).
The error in the subject line i am only seeing on one of three search head cluster members. Has anyone seen this before and even better, what do I do to resolve it?