I currently have Splunk on a central server and 3 other servers forwarding events to it. All the servers have been switched to a free license, however on the central server I'm getting a warning of "This pool contains slave(s) with 1 warnings". I didn't think it was possible to even set up slaves with a free license so I have no clue how to fix this problem, also doesn't help that Splunk won't tell you which server/slave is having the problems. I double checked all the server to verify that they were running with a free license and none were configured to be slaves. So any ideas of how to fix this problem?
The reason that your getting this error message warning of "This pool contains slave(s) with 1 warnings" is because you are using the same license on two servers. Splunk is aware that your trial license is in use on two indexing servers. Disabling the installation that is a duplicate and that will fix your problem.
I'm not sure which release your on but you can check which is the slave and master by going under Manager » Licensing.