Do you know any good mysql mailing list?
http://www.google.co.nz/search?q=mysql+mailing+list
I have question what is the different between /var/lib/mysql/mysql.sock /var/lib/mysql/mysqld.sock
I have very little knowledge of mysql, but my understanding is it's just a naming convention. CentOS uses mysql.sock for its mysqld service, and some other distributions use mysqld.sock.
It's just another method applications use to connect to mysql.
look at /etc/my.cnf to see where yours is configured to be.