Noise on new DS1522+

Hello guys,
I just installed DS1522+ with two 12TB WD RED plus. After two days there are still vibrations from running hdds. Is there any solution to fix it? I move there around 20k+ photos … so maybe still indexing? hibernation is on but I thing is still running. I moved from the old 213j with 2x3 WD red and that was really quiet. Thnx for your help.