I’ve had a problem with mysql failing to start with error 35 in the log file:
InnoDB: Unable to lock ./ibdata1, error: 35
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
What to do? Google and you get a lot of Linux people saying that the answer is to reboot the box. Hmm. Well you don’t have to.
What causes the error is mysqld crashing, usually when system resources are exhausted. Rebooting will, indeed, unlock ibdata1 but so will killing the process that locks it. Yet the server isn’t running, so how can this be? Well actually part of it is – just not the part the service manager sees.
Run “ps -auxww | grep mysql” and you’ll find a few more. Send them a kill, wait for it to work and then restart. Obviously you can only do this and expect it to work if you’ve sorted out the resource problem.