mysql.sock.lock with nothing in it was left behind after the reboot
When we attempted to start mysql we saw the following:
ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists
# service mysql start
Starting MySQL... ERROR! The server quit without updating PID file (/opt/CA/MySql/data/<hostname>.pid).
When looking at the /opt/CA/MySql/data/<hostname>.err file we saw the following
Server socket created on IP: '::'.
[ERROR] Unix socket lock file is empty /opt/CA/MySql/data/mysql.sock.lock.
[ERROR] Unable to setup unix socket lock file.