In one of my servers, from time to time, Mysql crashes. ISPConfig system should restart it, but doesn't. (I have not disabled any of the rescue items in UI (mysql, httpd, etc.) Any idea / suggestion?
The built-in rescue system is not that great, and we'll likely remove it in the future. It generally works, but on some systems, it's not reliably restarting services like in your case. I recommend using e.g. monit instead.