MySQL配置多实例

首先对没有时间看mysql文档的朋友明确几个概念：

一、mysqld读取my.cnf的顺序：

第一搜，首先读取/etc/my.cnf，多实例这个配置文件不会存在。：-（

第二搜，$datadir/my.cnf，在data目录下寻找此配置文件。

第三搜，defaultfile=/path/my.cnf 通常写在命令行上，mysqld_safe defaultfile=/tmp/my.cnf &等执行。

第四搜，~/my.cnf 当前用户下的配置文件。

二、Mysql的启动方式：

mysqld多进程运行的必要条件，就是pid文件，datadir，socket，port是独立分开的。

单一版本实现多实例
#pwd

/usr/local/

#touch my_multi.cnf

#cat my_multi.cnf

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

[mysqld1]
socket = /tmp/mysql_3301.sock
port = 3301
pid-file = /usr/local/mysql_3301/data/mysql_3301.pid
datadir = /usr/local/mysql_3301/data/
log = /usr/local/mysql_3301/data/mysql_3301.log
user = mysql

[mysqld2]
socket = /tmp/mysql_3302.sock
port = 3302
pid-file = /usr/local/mysql_3302/data/mysql_3302.pid
datadir = /usr/local/mysql_3302/data/
log = /usr/local/mysql_3302/data/mysql_3302.log
user = mysql

启动mysqld 的两个实例

/usr/bin/mysqld_multi –config-file=./my_multi.cnf start 1,2

Starting mysqld daemon with databases from /usr/local/mysql_3301/data/

Starting mysqld daemon with databases from /usr/local/mysql_3302/data/

查看3301,3302端口是否被监听
# netstat -lt |grep 33

tcp 0 0 *:3301 *:* LISTEN

tcp 0 0 *:3302 *:* LISTEN

测试mysql是否可以连通

#pwd

/usr/local/

通过/tmp/mysql_3301.sock连接3001端口的mysqld
# bin/mysql -u root -S /tmp/mysql_3301.sock -e “SELECT @@VERSION;”

停止3001端口的mysqld
# /usr/bin/mysqld_multi –config-file=./my_multi.cnf stop 1

STOPPING server from pid file /usr/local/mysql_3301/data/mysql_3301.pid

091010 11:56:04 mysqld ended
再次连接,系统会提示错误
# bin/mysql -u root -S /tmp/mysql_3301.sock -e “SELECT @@VERSION;”

ERROR 2002 (HY000):

Can’t connect to local MySQL server through socket ‘/tmp/mysql_3301.sock’ (2)

相同的步骤测试3002端口的mysqld，输出与上面相同。
# /usr/bin/mysql -u root -S /tmp/mysql_3302.sock -e “SELECT @@VERSION;”

# /usr/bin/mysqld_multi –config-file=./my_multi.cnf stop 2

# /usr/bin/mysql -u root -S /tmp/mysql_3302.sock -e “SELECT @@VERSION;”

补充上两句：
[Nova@imdba.cn mysql]# cp ../mysql-5.0.67/support-files/my-large.cnf /etc/my.cnf

[Nova@imdba.cn mysql]# cp ../mysql-5.0.67/support-files/mysql.server /etc/rc.d/init.d/mysqld

[Nova@imdba.cn mysql]# chkconfig –add mysql

[Nova@imdba.cn mysql]# chkconfig –level mysql 345 on

[Nova@imdba.cn mysql]# chkconfig –list mysql