I'm having a problem with a mysql server. The CPU usage goes up to 100% when the mysql server does something in the background. This is keeping the server for 8-10 minutes in dead position. MySQL reaches the 150 limit and the apache can't serve the sites either.
This happens at 3.40PM and 3.40AM too. I looked the crontab and I didn't find anything that could causing this.
The log says nothing either. Just qmail server send/receive regular mails in that time.
This is a plesk server with CentOS 5. Only the php and the httpd server was updated in the last 3 years.
(The MySQL is 5.0.22-2.2.el5_1.1 version) Basically every packages and the kernel too are the old except those two rpm. The plesk old too and about 10 complete updates left in the admin window.
Of course this is an important server for that Company and it serves about 15 domains and of course no local administrator who maintains the server whatsoever.
Sometimes the usage goes to high in a random time once/twice a day but the 3.40AM/PM are happens every day.
An infected site causing this or was it compromised and somewhere is a hidden MySQL or php script running at that particular time?
Or is it just because of the old MySQL server with the old rpms? (bug)
Anyway if someone has an idea what to look for that would be much appreciated.
Is there a crontab in the MySQL server or task scheduler? I don't know much about MySQL.