There might be unwanted events reporting data base and filling it. Run below query on mangement studio to see top events reported and
stop them reporting by configuring the ePO server settings.
select threateventid, count(threateventid)as threateventcount, threatname, threattype from epoevents
group by threateventid, threatname, threattype
order by threateventcount desc
Most probably, the informational events may be filling the space.
If yes then will suggest you to check the Event IDs from Event filtering (Menu=>Configuration=>Server setttings=>Event filtering).