[root@localhost ~]# vi /etc/my.cnf 添加：

[mysqld_multi]
mysqld = /usr/bin/mysqld_safe
mysqladmin = /usr/bin/mysqladmin

[mysqld2]
socket = /tmp/mysql.sock2
port = 3307
pid-file = /tmp/localhost.pid2
datadir = /mnt/data/mysqld2
[root@localhost ~]# mkdir -p /mnt/data/mysqld2
[root@localhost ~]# chown mysql:mysql /mnt/data/mysqld2

[root@localhost ~]# mysql_install_db --datadir /mnt/data/mysqld2 --user=mysql

启动实例：
[root@localhost ~]# mysqld_multi start 2

[root@localhost ~]# lsof -i:3306
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 27794 mysql 10u IPv4 42678 0t0 TCP *:mysql (LISTEN)
[root@localhost ~]# lsof -i:3307
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 27928 mysql 10u IPv4 42930 0t0 TCP *:opsession-prxy (LISTEN)
登陆第二个实例：
[root@localhost ~]# mysql -uroot -h127.0.0.1 -P3307 -p 通过-P指定端口号