Www-data is running the server in completly overload

Hey folks,
everyday, since 14 days now, my NC instance ist running into an overload for 30min. There is nothing in the nc log and anywhere else…
I watched via top which process is causing the overload and it looks like that the www-data user is doing something with mysql, and mysql then explodes the Ram plus 190% of the CPU…but still then nothing in the mysql error.logs…
Does anyone have a tip whereelse I can find some information?

you increase log level using config parameter


regular load could result from cron job - maybe you want to start there.

i increased the loglevel, but theres nothing to worry about. and no message about some cronjob issues…
any glue where i can dig deeper in the cron jobs?