一台数据库服务器为什么运行多个实例？
有一台MySQL数据库服务器硬件利用率往往在30%左右，那剩余的70%岂不是浪费了，这时就可以考虑运行多个MySQL服务，你可以做主从架构，读写分离，数据库隔离，容纳更多的并发链接，充分利用硬件资源，让服务器性能发挥最大化。
1、编译安装MySQL5.5
# yum install -y cmake gcc gcc-c++ make cmake ncurses ncurses-devel # groupadd mysql # useradd -g mysql -s /sbin/nologin mysql # tar zxvf mysql-5.5.31.tar.gz # cd mysql-5.5.31 # cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql5.5 -DSYSCONFDIR=/usr/local/mysql5.5/etc -DMYSQL_DATADIR=/usr/local/mysql5.5/data # make && make install # mkdir /usr/local/mysql5.5/etc # cp support-files/my-medium.cnf /usr/local/mysql5.5/etc/my.cnf # chown -R mysql.mysql /usr/local/mysql5.5/ # echo ‘PATH=$PATH:/usr/local/mysql5.5/bin' >> /etc/profile # source /etc/profile
3、初始化数据库实例
# mkdir /usr/local/mysql5.5/data3306 #创建数据库数据目录 # mkdir /usr/local/mysql5.5/data3307 # /usr/local/mysql5.5/scripts/mysql_install_db --basedir=/usr/local/mysql5.5/ --datadir=/usr/local/mysql5.5/data3306/ --user=mysql # /usr/local/mysql5.5/scripts/mysql_install_db --basedir=/usr/local/mysql5.5/ --datadir=/usr/local/mysql5.5/data3307/ --user=mysql
2、配置多实例信息并使用mysqld_multi工具集中管理
# cd /usr/local/mysql5.5/etc/ # vi my.cnf [mysqld_multi] mysqld = /usr/local/mysql5.5/bin/mysqld_safe mysqladmin = /usr/local/mysql5.5/bin/mysqladmin user = root #登陆数据库用户 password = 123 #登陆数据库密码，用于关闭数据库，两台数据库密码设置一样 [mysqld1] user = mysql port = 3306 socket = /tmp/mysql3306.sock pid-file = /usr/local/mysql5.5/data3306/mysql.pid basedir = /usr/local/mysql5.5 datadir = /usr/local/mysql5.5/data3306 log_error = /var/log/mysql/3306_error.log [mysqld2] user = mysql port = 3307 socket = /tmp/mysql3307.sock pid-file = /usr/local/mysql5.5/data3307/mysql.pid basedir = /usr/local/mysql5.5 datadir = /usr/local/mysql5.5/data3307 log_error = /var/log/mysql/3307_error.log
3、启动实例1,2
# 单个实例启动或关闭 # mysqld_multi --defaults-file=/usr/local/mysql5.5/etc/my.cnf start/stop 1 # mysqld_multi --defaults-file=/usr/local/mysql5.5/etc/my.cnf start/stop 2 # 双实例同时启动或关闭 # mysqld_multi --defaults-file=/usr/local/mysql5.5/etc/my.cnf start/stop 1,2 # 查看MySQL是否启动 # mysqld_multi --defaults-file=./my.cnf report 1,2 Reporting MySQL servers MySQL server from group: mysqld1 is running MySQL server from group: mysqld2 is running # netstat -antp |grep mysql tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 20896/mysqld tcp 0 0 0.0.0.0:3307 0.0.0.0:* LISTEN 21499/mysqld # 加入开机启动 echo "/usr/local/mysql5.5/mysqld_multi --defaults-file=/usr/local/mysql5.5/etc/my.cnf start 1,2" >> /etc/rc.local
注：如果不想用mysqld_multi工具，可以独立实例配置文件，自己启动或关闭，如下：
# /usr/local/mysql5.5/bin/mysqld_safe --defaults-extra-file=/usr/local/mysql5.5/etc/my3306.cnf --datadir=/usr/local/mysql5.5/data3306/ --user=mysql & # mysqladmin -uroot -p123 -S/tmp/mysql3306.sock shutdown
4、本地登录
# 首次登录先设置密码 # mysql -S /tmp/mysql3306.sock -P 3307 -uroot -p #直接回车进入 mysql> set password=password('123'); # mysql -S /tmp/mysql3307.sock -P 3307 -uroot -p mysql> set password=password('123');
5、远程登录（先开启远程访问权限）
mysql> grant all on *.* to'root'@'%' identified by '123'; # mysql -h 192.168.1.10 -P 3306 -uroot -p123 # mysql -h 192.168.1.10 -P 3307 -uroot -p123
