We are using a good monitoring tool named Zabbix, but today I have a serious problem. The size of the ibdata1 (InnoDB) is 16Gb and my hard disk is only 20GB. MySQL is stopped, and I'm unable to restart it.
I have resized my disk, and I have used Acronis Director to resize my /var partition to allow MySQL to restart.
The only problem is that I must find a solution to decrease the size of ibdata1. If you made some googling, there is no really a solution.