一个机器上安装多个mysql实例，除了将每个实例在不同的目录下编译安装，为每个实例指定不同的端口，socket，配置文件，安装目录等。还可以使用mysqld_multi方式。

mysqld_multi是mysql设计的专门用来管理不同端口，不同socket的mysql实例的工具。它可以同时启动，停止多个mysql实例，也可以查看这些实例的状态。

mysqld_multi会去配置文件my.cnf(或者是—defaults-file参数指定的配置文件)中检查每一个以[mysqldN]为开头的一组配置(N这里是数字)。这个N是mysqld_multi用来区分每一个mysql实例用的。用法如下：

mysqld_multi start|stop|reload|reportN1, N2, N3,… //reload等价于stop和start。

mysqld_multi需要的信息记录在配置文件my.cnf中的[mysqld_multi]组下。

注意，为了能用mysqld_multi统计管理所有的mysql实例，该管理账号必须存在于所有的mysql实例上，而且密码也一致。

以下是我做的测试以及安装步骤：

1、 编写配置文件my.cnf，如下：

[root@CentOSMysql1 etc]# catmy.cnf

[mysqld_multi]

mysqld=mysqld_safe

#表示用mysqld_safe来启动mysql

mysqladmin=/usr/local/mysql/bin/mysqladmin

#指定mysqladmin工具的路径

log=/usr/local/mysql/mysqld_multi.log

#指定mysqld_multi的日志文件

user=root

pass=123456

#指定使用mysqld_multi工具的用户和密码

[mysqld3307]

#指定实例编号为3307的一些配置参数

datadir=/opt/data3307

port=3307

socket=/tmp/mysql.sock3307

[mysqld3308]

#指定实例编号为3308的一些配置参数

datadir=/opt/data3308

port=3308

socket=/tmp/mysql.sock3308

[mysqld56]

#指定实例编号为56的一些配置参数

basedir=/usr/local/mysql56/

datadir=/opt/data56

socket=/tmp/mysql.sock56

port=3310

2、 准备安装之前工作

(1)查看是否有mysql用户和mysql组

[root@CentOSMysql1 etc]# catgroup |grep mysql

[root@CentOSMysql1 etc]#groupadd mysql

[root@CentOSMysql1 mysql]# cat/etc/passwd|grep mysql

[root@CentOSMysql1 etc]#useradd -g mysql mysql

(2)下载mysql的安装文件。这里我下载的都是linux generic类型的

[root@CentOStest1 opt]# wgethttp://downloads.mysql.com/archives/get/file/mysql-5.6.19-linux-glibc2.5-x86_64.tar.gz

[root@CentOStest1opt]# wget http://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-5.7.17-linux-glibc2.5-x86_64.tar.gz

(3)解压这些安装包

[root@CentOSMysql1 opt]# tar-zxf mysql-5.6.34-linux-glibc2.5-x86_64.tar.gz

[root@CentOSMysql1 opt]# tar-zxf mysql-5.7.16-linux-glibc2.5-x86_64.tar.gz

3、 安装编号为3307的mysql实例，这里我计算用mysql5.7的版本。

[root@CentOSMysql1 opt]#mv mysql-5.7.16-linux-glibc2.5-x86_64 /usr/local

[root@CentOSMysql1 opt]#cd /usr/local/

[root@CentOSMysql1 local]#ln –s mysql-5.7.16-linux-glibc2.5-x86_64mysql

[root@CentOSMysql1 local]# cdmysql

[root@CentOSMysql1 mysql]# chown -R mysql:mysql .

[root@CentOSMysql1 mysql]# bin/mysqld--initialize --user=mysql --datadir=/opt/data3307

//这条命令执行成功之后，会在结尾打印出临时密码，如下：

2017-12-21T02:08:32.598340Z 0[Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use--explicit_defaults_for_timestamp server option (see documentation for moredetails).

2017-12-21T02:08:33.002195Z 0[Warning] InnoDB: New log files created, LSN=45790

2017-12-21T02:08:33.090315Z 0[Warning] InnoDB: Creating foreign key constraint system tables.

2017-12-21T02:08:33.179548Z 0[Warning] No existing UUID has been found, so we assume that this is the firsttime that this server has been started. Generating a new UUID:d898cae9-e5f3-11e7-9e66-000c299323ae.

2017-12-21T02:08:33.181477Z 0[Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed'cannot be opened.

2017-12-21T02:08:33.184759Z 1[Note] A temporary password is generated for root@localhost: L;0/g:XaweYi

[root@CentOSMysql1mysql]# bin/mysql_ssl_rsa_setup--datadir=/opt/data3307

到这里，编号为3307的实例初步安装完毕，还剩下一个步骤就是修改临时密码。改密码之前需要把其所在mysql服务启动起来，这里我们用mysqld_multi启动，先查看下状态，如下：

[root@CentOSMysql1bin]# mysqld_multireport

-bash: mysqld_multi: commandnot found

解决方法为将mysqld_multi工具所在的路径添加到环境变量中去：

[root@CentOSMysql1 bin]# vi/etc/profile

//在文件尾部添加以下语句

PATH=/usr/local/mysql/bin:$PATH

"/etc/profile" 79L,1828C written

[root@CentOSMysql1 bin]#source /etc/profile

环境变量生效之后重试

[root@CentOSMysql1 mysql]#mysqld_multi report

Reporting MySQL servers

MySQL server from group:mysqld3307 is not running

MySQL server from group:mysqld3308 is not running

MySQL server from group:mysqld56 is not running

[root@CentOSMysql1 mysql]#mysqld_multi start 3307

[root@CentOSMysql1 mysql]#mysqld_multi report

Reporting MySQL servers

MySQL server from group:mysqld3307 is running

MySQL server from group: mysqld3308is not running

MySQL server from group:mysqld56 is not running

可以看到编号3307的mysql实例已经启动，然后修改root密码。因为my.cnf里面配置了root用户的密码是123456，所以现在我们将root的密码改为“123456”:

[root@CentOSMysql1mysql]# mysql -uroot -p -S /tmp/mysql.sock3307

Enter password:

//这里输出刚才安装时出现的临时密码。

mysql> set password=password("123456");

到这里，编号为3307的实例安装完毕。

4、 安装编号为3308的mysql实例，这里仍用mysql5.7的版本，但是端口号以及datadir要根据my.cnf中的来。

[root@CentOSMysql1 mysql]#bin/mysqld --initialize --user=mysql --datadir=/opt/data3308

2017-12-21T02:36:31.294011Z 0[Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use--explicit_defaults_for_timestamp server option (see documentation for moredetails).

2017-12-21T02:36:31.779696Z 0[Warning] InnoDB: New log files created, LSN=45790

2017-12-21T02:36:31.881428Z 0[Warning] InnoDB: Creating foreign key constraint system tables.

2017-12-21T02:36:31.948774Z 0[Warning] No existing UUID has been found, so we assume that this is the firsttime that this server has been started. Generating a new UUID: c138a63c-e5f7-11e7-8f7a-000c299323ae.

2017-12-21T02:36:31.950062Z 0[Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed'cannot be opened.

2017-12-21T02:36:31.953758Z 1[Note] A temporary password is generated for root@localhost: whKyXCtxz9;g

//临时密码同样在尾处生成。

[root@CentOSMysql1 mysql]#bin/mysql_ssl_rsa_setup--datadir=/opt/data3308

拉起编号3308的mysql实例服务

[root@CentOSMysql1 mysql]#mysqld_multi start 3308

修改编号3308的mysql实例中root用户的密码为“123456”。

[root@CentOSMysql1 mysql]#mysql -uroot -p -S /tmp/mysql.sock3308

Enter password:

//这里输出刚才安装时出现的临时密码。

mysql> setpassword=password("123456");

到这里，编号为3308的实例安装完毕。

5、 安装编号为56的mysql实例，这里使用mysql5.6的版本，由安装目录，端口号以及datadir根据my.cnf中的来。

[root@CentOSMysql1 opt]#mv mysql-5.6.34-linux-glibc2.5-x86_64/usr/local

[root@CentOSMysql1 opt]#cd/usr/local/

[root@CentOSMysql1 local]#ln–s mysql-5.6.34-linux-glibc2.5-x86_64 mysql56

[root@CentOSMysql1 local]# cdmysql56

[root@CentOSMysql1 mysql56]#chown -R mysql:mysql .

[root@CentOSMysql1 mysql56]#scripts/mysql_install_db --user=mysql--datadir=/opt/data56

这一步和mysql5.7有些不一样，不会生成临时密码。Mysql5.6的临时密码默认是空。

[root@CentOSMysql1 local]#mysqld_multi start 56

拉起编号56的mysql实例服务

[root@CentOSMysql1 local]#mysql -uroot -p -S /tmp/mysql.sock56

修改编号56的mysql实例中root用户的密码为“123456”。

mysql> setpassword="123456";

ERROR 1372 (HY000): Passwordhash should be a 41-digit hexadecimal number

mysql> setpassword=password("123456");

到这里，编号为56的实例安装完毕。

6、 最后，试试用mysqld_multi统一起停所有的mysql实例

[root@CentOSMysql1 ~]#mysqld_multi report

Reporting MySQL servers

MySQL server from group:mysqld3307 is running

MySQL server from group:mysqld3308 is running

MySQL server from group:mysqld56 is running

[root@CentOSMysql1 ~]#mysqld_multi report

Reporting MySQL servers

MySQL server from group:mysqld3307 is running

MySQL server from group:mysqld3308 is running

MySQL server from group:mysqld56 is running

[root@CentOSMysql1 ~]#mysqld_multi stop

[root@CentOSMysql1 ~]#mysqld_multi report

Reporting MySQL servers

MySQL server from group:mysqld3307 is not running

MySQL server from group:mysqld3308 is not running

MySQL server from group:mysqld56 is not running

[root@CentOSMysql1 ~]#mysqld_multi start

[root@CentOSMysql1 ~]#mysqld_multi report

Reporting MySQL servers

MySQL server from group:mysqld3307 is running

MySQL server from group:mysqld3308 is running

MySQL server from group:mysqld56 is running