The number of slaves in the warning is incorrect. It is a bug. That is confusing. But, the violation of the pool itself is correct information.
Here is additional useful information to investigate indexing volume;
http://wiki.splunk.com/Community:TroubleshootingIndexedDataVolume
Also, Deployment Monitor app at the license master also should show historical indexed volume if it is enabled. Please keep in mind that the Deployment Monitor's all view should work properly only when the license master is a search head of all the license slaves. Otherwise, some dashboards information is not proper.
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