From the IIQ documentation:   InsightIQ begins deleting older data from the datastore when the datastore becomes 92% full. If InsightIQ is unable to delete data from the datastore, and the datastore continues to grow, InsightIQ will stop monitoring clusters when the InsightIQ datastore becomes 98% full. If this happens, you must manually delete data from the datastore before InsightIQ can continue monitoring clusters. InsightIQ is unable to automatically delete the following types of data from the datastore, and you must delete these types of data manually.  Cheers Rob 
Hi InsightIQ stops when there are less that 10% free disk space on the cluster. Is there a way to tell InsightIQ to continue running?  Thanks and kind regards Henrik Ravn
InsightIQ stopping when low on free disk