MySQL数据库的集中化运维，可以通过在一台服务器上，部署运行多个MySQL服务进程，通过不同的socket监听不同的服务端口来提供各自的服务。各个实例之间是相互独立的，每个实例的datadir, port, socket, pid都是不同的。
1.有效利用服务器资源，当单个服务器资源有剩余时，可以充分利用剩余的资源提供更多的服务。
2.资源互相抢占问题，当某个服务实例服务并发很高时或者开启慢查询时，会消耗更多的内存、CPU、磁盘IO资源，导致服务器上的其他实例提供服务的质量下降。
[root@dl_235 tools]# cat /etc/redhat-release
CentOS Linux release 7.8.2003 (Core)
首先安装mysql，此处不做介绍，正常安装即可：
#创建多实例数据目录及日志文件[如果不创建日志文件后面会报错]
mkdir -vp /home/deploy/mysql_data{1..8}/data
touch /home/deploy/mysql_data{1..8}/mysql.log
#修改 MySQL 多实例数据目录所属用户与所属组
chown mysql.mysql -R /home/deploy/mysql_data{1..8}
#配置 MySQL 配置文件 /etc/my.cnf
[mysqld_multi] mysqld = /home/deploy/mysql/bin/mysqld_safe mysqladmin = /home/deploy/mysql/bin/mysqladmin log = /tmp/mysql_multi.log user = mysql #sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION [mysqld1] event_scheduler=0 datadir = /home/deploy/mysql_data1/data socket = /home/deploy/mysql_data1/mysql.sock pid-file = /home/deploy/mysql_data1/mysql.pid log-error = /home/deploy/mysql_data1/mysql.log port = 3301 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 21 [mysqld2] event_scheduler=0 datadir = /home/deploy/mysql_data2/data socket = /home/deploy/mysql_data2/mysql.sock pid-file = /home/deploy/mysql_data2/mysql.pid log-error = /home/deploy/mysql_data2/mysql.log port = 3302 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 22 [mysqld3] event_scheduler=0 datadir = /home/deploy/mysql_data3/data socket = /home/deploy/mysql_data3/mysql.sock pid-file = /home/deploy/mysql_data3/mysql.pid log-error = /home/deploy/mysql_data3/mysql.log port = 3303 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 23 [mysqld4] event_scheduler=0 datadir = /home/deploy/mysql_data4/data socket = /home/deploy/mysql_data4/mysql.sock pid-file = /home/deploy/mysql_data4/mysql.pid log-error = /home/deploy/mysql_data4/mysql.log port = 3304 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 24 [mysqld5] event_scheduler=0 datadir = /home/deploy/mysql_data5/data socket = /home/deploy/mysql_data5/mysql.sock pid-file = /home/deploy/mysql_data5/mysql.pid log-error = /home/deploy/mysql_data5/mysql.log port = 3305 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 25 [mysqld6] event_scheduler=0 datadir = /home/deploy/mysql_data6/data socket = /home/deploy/mysql_data6/mysql.sock pid-file = /home/deploy/mysql_data6/mysql.pid log-error = /home/deploy/mysql_data6/mysql.log port = 3306 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 26 [mysqld7] event_scheduler=0 datadir = /home/deploy/mysql_data7/data socket = /home/deploy/mysql_data7/mysql.sock pid-file = /home/deploy/mysql_data7/mysql.pid log-error = /home/deploy/mysql_data7/mysql.log port = 3307 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 27 [mysqld8] event_scheduler=0 datadir = /home/deploy/mysql_data8/data socket = /home/deploy/mysql_data8/mysql.sock pid-file = /home/deploy/mysql_data8/mysql.pid log-error = /home/deploy/mysql_data8/mysql.log port = 3308 user = mysql innodb_buffer_pool_size = 32M skip-name-resolve = 0 server-id = 28#初始化各个实例,--initialize-insecure为不设置密码
/home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data1/data /home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data2/data /home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data3/data /home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data4/data /home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data5/data /home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data6/data /home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data7/data /home/deploy/mysql/bin/mysqld --defaults-file=/etc/my.cnf --initialize-insecure --user=mysql --basedir=/home/deploy/mysql --datadir=/home/deploy/mysql_data8/data#复制脚本及修改脚本
#复制多实例脚本到服务管理目录下 [ /etc/init.d/ ] cp /home/deploy/mysql/support-files/mysqld_multi.server /etc/init.d/mysqld_multi #添加脚本执行权限 chmod +x /etc/init.d/mysqld_multi #注意修改mysqld_multi脚本目录，这里修改为 basedir=/home/deploy//mysql bindir=/home/deploy/mysql/bin #添加进service服务管理 chkconfig --add mysqld_multi
#查个多实例状态
[root@dl_235 deploy]# /etc/init.d/mysqld_multi report Reporting MySQL servers MySQL server from group: mysqld1 is not running MySQL server from group: mysqld2 is not running MySQL server from group: mysqld3 is not running MySQL server from group: mysqld4 is not running MySQL server from group: mysqld5 is not running MySQL server from group: mysqld6 is not running MySQL server from group: mysqld7 is not running MySQL server from group: mysqld8 is not running#启动多实例并查看状态和端口
[root@dl_235 ~]# /etc/init.d/mysqld_multi start
[root@dl_235 ~]# /etc/init.d/mysqld_multi report
Reporting MySQL servers
MySQL server from group: mysqld1 is running
MySQL server from group: mysqld2 is running
MySQL server from group: mysqld3 is running
MySQL server from group: mysqld4 is running
MySQL server from group: mysqld5 is running
MySQL server from group: mysqld6 is running
MySQL server from group: mysqld7 is running
MySQL server from group: mysqld8 is running
[root@dl_235 ~]# ss -lntup|grep 33
tcp LISTEN 0 128 [::]:3301 [::]:* users:(("mysqld",pid=91390,fd=35))
tcp LISTEN 0 128 [::]:3302 [::]:* users:(("mysqld",pid=83518,fd=40))
tcp LISTEN 0 128 [::]:3303 [::]:* users:(("mysqld",pid=91551,fd=20))
tcp LISTEN 0 128 [::]:3304 [::]:* users:(("mysqld",pid=83540,fd=37))
tcp LISTEN 0 128 [::]:3305 [::]:* users:(("mysqld",pid=83565,fd=28))
tcp LISTEN 0 128 [::]:3306 [::]:* users:(("mysqld",pid=83543,fd=31))
tcp LISTEN 0 128 [::]:3307 [::]:* users:(("mysqld",pid=91553,fd=34))
tcp LISTEN 0 128 [::]:3308 [::]:* users:(("mysqld",pid=83581,fd=37))
[root@dl_235 ~]# mysql -uroot -p -S /home/deploy/mysql_data1/mysql.sock Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 5 Server version: 5.7.22-log Source distribution Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>