Currently we believe our system is configured to retain logs for the approximate 5.9 years but when we do searches we can only go back approximately 8 moths which appears to drop off to 8 months every week. Here is the configuration;
Review the daily ingestion rate (indexed data/day) for each of the indexes with configuration frozenTimePeriodInSecs = 188697600 (2,184 DAYS) and calculate the storage required for your desired retention. Then compare that with your available disk capacity. Its likely that you don't have enough storage to store data for 5.9years and hence they are ageing out.