Under CDR tools, Configure Automatic Purge option, 180 is the max value. From reading the help page, the high/low watermark applys to the min number of records and not max number. So, is 180 days the most records you can have with 5.x without using a CDR billing server?
I don't see a way to disable automatic purge like in older windows based versions.
In 5.x and 6.x the max size of the CAR DB is already pre-allocated so it cannot grow as it could on windows versions, so records need to be purged to accomplish this and not go above the DB size limit
if this helps, please rate