If you have this error:

InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process

It means you have have running several mysql instances.

Fix.

killall mysqld
kill -9 `ps -aux | grep mysql | awk ‘{print $2}’ or maybe:
pgrep -u mysql | xargs kill -9

service mysqld start