For a strange reason, after a reboot the Watchdog module does not recognize the mysql process (even if it is started and it is working) and tries to restart it. Actually a new mysql process is started thus blocking mysql, the following lines appear in the mysql log file: InnoDB: Unable to lock ./ibdata1, error: 11 InnoDB: Check that you do not already have another mysqld process InnoDB: using the same InnoDB data or log files. After this point, mysql stops to accept connections. I don't understand why, but it is a weird behaviour of the mysql script which usually does not start another service instance. The sequence of operations is: 1) start mysql at boot, it works perfectly 2) watchdog checks mysql, does not recognize its presence and tries to restart it 3) mysql start a new instance that block connections any idea?