Reamon has correctly pointed out. The storage file size will increase if there are any client queues getting filled and not getting cleared up.
Check all the client queues via MWS and if you find any explicit destroy clients which are no longer required then clear the queues and destroy the clients.
Somtimes some client are required but the subscription trigger is switched OFF, in this case switch ON the subscription trigger.
Sometimes everything looks fine but trigger does not work/subscribe, in that case you might want to check out latest broker fixes.
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