Upgrade mysql (5.1) to mysql55 on CENTOS6

To upgrade from mysql (default ver 5.1) to mysql55 (IUS ver 5.5):

Replace residual mysql component to mysql55:

[root@localhost ~]# yum replace mysql-libs --replace-with mysql55

Install server and client:

[root@localhost ~]# yum install mysql55-server mysql55

Start server upon reboot:

[root@localhost ~]# chkconfig mysqld on 

Start server service:

[root@localhost ~]# service mysqld start

Change root password:

[root@localhost ~]# mysqladmin -u root password