基于mysqld_multi实现MySQL 5.7.24多实例多进程配置
准备一台主机192.168.200.10
首先所有主机关闭防火墙与selinux
[root@localhost ~]# iptables -F
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# systemctl disable firewalld
[root@localhost ~]# setenforce 0
[root@localhost ~]# sed -i '/SELINUX/ s/enforcing/disabled/g' /etc/sysconfig/selinux
一、创建并初始化数据目录
几个实例要分开运行，必然要把数据库文件放到不同目录中，所以第一步是要建立各个实例的数据目录，这里假设我们要运行三个实例，端口分别是3306,3307,3308，为了方便维护，我们把数据文件夹也按照端口号来命名：
[root@localhost ~]# mkdir -p /data/mysql/{3306,3307,3308}
[root@localhost ~]# chown mysql:mysql /data/mysql/{3306,3307,3308}
[root@localhost ~]# ls -ld /data/mysql/{3306,3307,3308}
drwxr-xr-x 2 mysql mysql 6 12月 7 16:37 /data/mysql/3306
drwxr-xr-x 2 mysql mysql 6 12月 7 16:37 /data/mysql/3307
drwxr-xr-x 2 mysql mysql 6 12月 7 16:37 /data/mysql/3308
二、通过配置文件指定并初始化数据目录
[root@localhost ~]# cp /etc/my.cnf /data/mysql/3308.cnf
[root@localhost ~]# vim /data/mysql/3308.cnf
[mysqld]
port=3308
datadir=/data/mysql/3308/
socket=/tmp/mysql3308.sock
symbolic-links=0
[mysqld_safe]
log-error=/data/mysql/3308.log
pid-file=/usr/local/mysql/data/3308.pid
[client]
port=3308
socket=/tmp/mysql3308.sock
[root@localhost ~]# mysqld --defaults-file=/data/mysql/3308.cnf --initialize-insecure --user=mysql
[root@localhost ~]# vim /data/mysql/3306.cnf
[mysqld]
port=3306
datadir=/data/mysql/3306/
socket=/tmp/mysql3306.sock
symbolic-links=0
[mysqld_safe]
log-error=/data/mysql/3306.log
pid-file=/usr/local/mysql/data/3306.pid
[client]
port=3306
socket=/tmp/mysql3306.sock
[root@localhost ~]# vim /data/mysql/3307.cnf
[mysqld]
port=3307
datadir=/data/mysql/3307/
socket=/tmp/mysql3307.sock
symbolic-links=0
[mysqld_safe]
log-error=/data/mysql/3307.log
pid-file=/usr/local/mysql/data/3307.pid
[client]
port=3307
socket=/tmp/mysql3307.sock
[root@localhost ~]# mysqld --defaults-file=/data/mysql/3307.cnf --initialize-insecure --user=mysql
[root@localhost ~]# mysqld --defaults-file=/data/mysql/3306.cnf --initialize-insecure --user=mysql
二、配置my.cnf文件集中管理多个实例
[root@localhost ~]# cp /etc/my.cnf /etc/my.cnf.bak
[root@localhost ~]# vim /etc/my.cnf
[mysqld_multi]
mysqld=/usr/local/mysql/bin/mysqld_safe
mysqladmin=/usr/local/mysql/bin/mysqladmin
[mysqld1]
port=3306
socket=/tmp/mysql3306.sock
datadir=/data/mysql/3306/
skip-external-locking
log-bin=/data/mysql/3306/mysql-bin
server-id=3306
user=mysql
[mysqld2]
port=3307
socket=/tmp/mysql3307.sock
datadir=/data/mysql/3307/
skip-external-locking
log-bin=/data/mysql/3307/mysql-bin
server-id=3307
user=mysql
[mysqld3]
port=3308
socket=/tmp/mysql3308.sock
datadir=/data/mysql/3308/
skip-external-locking
log-bin=/data/mysql/3308/mysql-bin
server-id=3308
user=mysql
[mysql]
no-auto-rehash
mysqld_multi的配置文件和一般MySQL配置不同，没有[mysqld]段，取而代之的是[mysqld1]、[mysqld2]等配置段，每个配置段代表一个MySQL实例。
三、管理多个MySQL实例
1，启动多个MySQL实例
启动多个实例时需要一个启动脚本，这个脚本一般在/usr/local/mysql/support-files目录下的mysqld_multi.server文件
[root@localhost ~]# cp /usr/local/mysql/support-files/mysqld_multi.server /etc/init.d/mysqld_multi
启动多个MySQL实例
[root@localhost ~]# /etc/init.d/mysqld_multi start 1-3
启动三个MySQL实例，注意这里的数字和my.cnf中的[mysqldN]对应，1-3就是启动[mysqld1]、[mysqld2]、[mysqld3]配置段的MySQL实例。
[root@localhost ~]# netstat -lnpt | grep -E "3306|3307|3308"
tcp6 0 0 :::3306 :::* LISTEN 2744/mysqld
tcp6 0 0 :::3307 :::* LISTEN 65502/mysqld
tcp6 0 0 :::3308 :::* LISTEN 65499/mysqld
四、root账户管理
前面初始化数据库时用的是--initialize-insecure参数，所以我们初始化的数据库，root账户是没有密码的，要先改密码为123456：
mysqladmin -uroot password '123456' -S /tmp/mysql3306.sock
mysqladmin -uroot password '123456' -S /tmp/mysql3307.sock
mysqladmin -uroot password '123456' -S /tmp/mysql3308.sock
五、连接mysql多实例：
[root@localhost ~]# mysql -u root -p123456 -S /tmp/mysql3306.sock
[root@localhost ~]# mysql -u root -p123456 -S /tmp/mysql3307.sock
[root@localhost ~]# mysql -u root -p123456 -S /tmp/mysql3308.sock