Freeradius 3.0 with mySQL Database on Qnap-Server

Hi everyboday, I have an issue with Freeradius running on a raspberry pi. The mySQL database is on a qnap TS559pro+. Everything runs fine, but the Harddisks of the QNAP will go to Sleep-Mode after an hour. The issue is, that my Cisco Switch sends out requests to the radius and gets a reject reply because the database on the Qnap needs some time to restart the Harddisks. How can i configre the delay-time for the RADIUS until he sends out the reject reply to the Switch? Spartacus