大纲
一、主从复制复制原理
二、主从复制的作用及复制类型
三、MySQL5.5异步复制的实现
四、MySQL5.5半同步复制的实现
一、主从复制原理
工作原理
1、当Master接收到了一个写请求，处理写请求，将结果保存至磁盘中，并且会将此操作记录到二进制日志文件中
2、Slave会从Master的二进制日志中读取其中的事件保存至本地的中继日志中
3、Slave会启动一个线程来逐条读取中继日志中的事件并应用于本地的
二、主从复制的作用及复制类型
复制的作用
辅助实现备份
提供类似高可用的机制
异地容灾
scale out：分摊负载，如实现读写分离
复制类型
基于语句(statement)复制优点是基于语句的复制的二进制日志可以很好的进行压缩，而且日志的数据量也较小，缺点是基于语句的复制必须是串行化。
基于行复制(Row-Based Replication)，在二进制日志中记录下实际数据的改变,优点就是可以对任何语句都能正确工作，一些语句的效率更高,缺点就是二进制日志会很大，不能使用mysqlbinlog来查看二进制日志.
混合类型(mixed)的复制,默认采用基于语句的复制，一旦发现基于语句的无法精确的复制时，就会采用基于行的复制.
三、MySQL5.5异步复制的实现
系统环境
CentOS5.8 x86_64
软件包
mysql-5.5.28-linux2.6-x86_64.tar.gz(二进制安装包)
1、Master安装并配置MySQL
数据目录底层最好是个逻辑卷，我这里就不再演示逻辑卷的创建了，我的博文中有，此处没有使用逻辑卷 准备数据目录并添加mysql用户 [root@Master ~]# mkdir -pv /mydata/data mkdir: created directory `/mydata‘ mkdir: created directory `/mydata/data‘ [root@Master ~]# groupadd -g 3306 mysql [root@Master ~]# useradd -u 3306 -g mysql -M -s /sbin/nologin -d /mydata/data/ mysql [root@Master ~]# chown -R mysql.mysql /mydata/data/ 解压并初始化mysql [root@Master ~]# cd /tmp/ [root@Master tmp]# tar xf mysql-5.5.28-linux2.6-x86_64.tar.gz -C /usr/local/ [root@Master tmp]# cd /usr/local/ [root@Master local]# ln -sv mysql-5.5.28-linux2.6-x86_64 mysql create symbolic link `mysql‘ to `mysql-5.5.28-linux2.6-x86_64‘ [root@Master local]# cd mysql [root@Master mysql]# chown -R root.mysql ./* [root@Master mysql]# ll total 132 drwxr-xr-x 2 root mysql 4096 Jan 15 15:18 bin -rw-r--r-- 1 root mysql 17987 Aug 29 2012 COPYING drwxr-xr-x 4 root mysql 4096 Jan 10 12:01 data drwxr-xr-x 2 root mysql 4096 Jan 15 15:17 docs drwxr-xr-x 3 root mysql 4096 Jan 15 15:18 include -rw-r--r-- 1 root mysql 7604 Aug 29 2012 INSTALL-BINARY drwxr-xr-x 3 root mysql 4096 Jan 15 15:18 lib drwxr-xr-x 4 root mysql 4096 Jan 10 12:02 man drwxr-xr-x 10 root mysql 4096 Jan 15 15:18 mysql-test -rw-r--r-- 1 root mysql 2552 Aug 29 2012 README drwxr-xr-x 2 root mysql 4096 Jan 15 15:18 scripts drwxr-xr-x 27 root mysql 4096 Jan 15 15:18 share drwxr-xr-x 4 root mysql 4096 Jan 15 15:18 sql-bench drwxr-xr-x 2 root mysql 4096 Jan 15 15:18 support-files [root@Master mysql]# scripts/mysql_install_db --user=mysql --datadir=/mydata/data/ Installing MySQL system tables... OK Filling help tables... OK To start mysqld at boot time you have to copy support-files/mysql.server to the right place for your system PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER ! To do so, start the server, then issue the following commands: ./bin/mysqladmin -u root password ‘new-password‘ ./bin/mysqladmin -u root -h Master password ‘new-password‘ Alternatively you can run: ./bin/mysql_secure_installation which will also give you the option of removing the test databases and anonymous user created by default. This is strongly recommended for production servers. See the manual for more instructions. You can start the MySQL daemon with: cd . ; ./bin/mysqld_safe & You can test the MySQL daemon with mysql-test-run.pl cd ./mysql-test ; perl mysql-test-run.pl Please report any problems with the ./bin/mysqlbug script! 复制配置文件与服务启动脚本 [root@Master mysql]# cp support-files/my-large.cnf /etc/my.cnf [root@Master mysql]# cp support-files/mysql.server /etc/rc.d/init.d/mysqld [root@Master mysql]# chkconfig --add mysqld 修改配置文件增加或修改如下行 [root@Master mysql]# vim /etc/my.cnf [mysqld] datadir = /mydata/data innodb_file_per_table = 1 log-bin=master-bin log-bin-index=master-bin.index 增加PATH环境变量 [root@Master mysql]# echo ‘export PATH=$PATH:/usr/local/mysql/bin‘ > /etc/profile.d/mysql.sh [root@Master mysql]# . /etc/profile.d/mysql.sh 启动服务并创建复制用户 [root@Master mysql]# service mysqld start Starting MySQL.... [ OK ] [root@Master mysql]# mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 1 Server version: 5.5.28-log MySQL Community Server (GPL) Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the buffer. mysql> GRANT REPLICATION SLAVE ON *.* TO ‘repuser‘@‘172.16.%.%‘ IDENTIFIED BY ‘repuser‘; Query OK, 0 rows affected (0.34 sec) mysql> FLUSH PRIVILEGES; Query OK, 0 rows affected (0.02 sec) mysql> \q Bye 将mysql的二进制包和配置文件拷贝至从节点 [root@Master mysql]# scp /tmp/mysql-5.5.28-linux2.6-x86_64.tar.gz Slave:/tmp mysql-5.5.28-linux2.6-x86_64.tar.gz 100% 178MB 7.4MB/s 00:24 [root@Master mysql]# scp /etc/my.cnf Slave:/etc/ my.cnf 100% 4745 4.6KB/s 00:00
2、Slave安装并配置MySQL
准备数据目录并添加mysql用户 [root@Slave ~]# mkdir -pv /mydata/data mkdir: created directory `/mydata‘ mkdir: created directory `/mydata/data‘ [root@Slave ~]# groupadd -g 3306 mysql [root@Slave ~]# useradd -u 3306 -g mysql -M -s /sbin/nologin -d /mydata/data/ mysql [root@Slave ~]# chown -R mysql.mysql /mydata/data/ 解压并初始化mysql [root@Slave ~]# cd /tmp/ [root@Slave tmp]# tar xf mysql-5.5.28-linux2.6-x86_64.tar.gz -C /usr/local/ [root@Slave tmp]# cd /usr/local/ [root@Slave local]# ln -sv mysql-5.5.28-linux2.6-x86_64 mysql create symbolic link `mysql‘ to `mysql-5.5.28-linux2.6-x86_64‘ [root@Slave local]# cd mysql [root@Slave mysql]# chown -R root.mysql ./* [root@Slave mysql]# ll total 132 drwxr-xr-x 2 root mysql 4096 Jan 15 15:45 bin -rw-r--r-- 1 root mysql 17987 Aug 29 2012 COPYING drwxr-xr-x 4 root mysql 4096 Jan 10 11:15 data drwxr-xr-x 2 root mysql 4096 Jan 15 15:45 docs drwxr-xr-x 3 root mysql 4096 Jan 15 15:46 include -rw-r--r-- 1 root mysql 7604 Aug 29 2012 INSTALL-BINARY drwxr-xr-x 3 root mysql 4096 Jan 15 15:46 lib drwxr-xr-x 4 root mysql 4096 Jan 10 11:16 man drwxr-xr-x 10 root mysql 4096 Jan 15 15:46 mysql-test -rw-r--r-- 1 root mysql 2552 Aug 29 2012 README drwxr-xr-x 2 root mysql 4096 Jan 15 15:46 scripts drwxr-xr-x 27 root mysql 4096 Jan 15 15:46 share drwxr-xr-x 4 root mysql 4096 Jan 15 15:46 sql-bench drwxr-xr-x 2 root mysql 4096 Jan 15 15:46 support-files [root@Slave mysql]# scripts/mysql_install_db --user=mysql --datadir=/mydata/data/ Installing MySQL system tables... OK Filling help tables... OK To start mysqld at boot time you have to copy support-files/mysql.server to the right place for your system PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER ! To do so, start the server, then issue the following commands: ./bin/mysqladmin -u root password ‘new-password‘ ./bin/mysqladmin -u root -h Slave password ‘new-password‘ Alternatively you can run: ./bin/mysql_secure_installation which will also give you the option of removing the test databases and anonymous user created by default. This is strongly recommended for production servers. See the manual for more instructions. You can start the MySQL daemon with: cd . ; ./bin/mysqld_safe & You can test the MySQL daemon with mysql-test-run.pl cd ./mysql-test ; perl mysql-test-run.pl Please report any problems with the ./bin/mysqlbug script! 复制服务启动脚本 [root@Slave mysql]# cp support-files/mysql.server /etc/rc.d/init.d/mysqld [root@Slave mysql]# chkconfig --add mysqld 修改配置文件做如下修改 [root@Slave mysql]# vim /etc/my.cnf [mysqld] 这两行要注释掉，从节点不开启二进制日志功能 #log-bin=Slave-bin #log-bin-index=Slave-bin.index 修改server_id，不能与主节点重复，要全局唯一 server-id = 11 增加中继日志功能 relay-log = relay-log relay-log-index = relay-log.index 使从节点只读 read-only = ON 增加PATH环境变量并使之生效 [root@Slave mysql]# echo ‘export PATH=$PATH:/usr/local/mysql/bin‘ > /etc/profile.d/mysql.sh [root@Slave mysql]# . /etc/profile.d/mysql.sh 启动服务 [root@Slave ~]# service mysqld start Starting MySQL.... [ OK ]
3、启动Slave上的复制功能
首次在Master上查看当前二进制日志所处的position [root@Master mysql]# mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 3 Server version: 5.5.28-log MySQL Community Server (GPL) Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the buffer. mysql> SHOW MASTER STATUS; +-------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +-------------------+----------+--------------+------------------+ | master-bin.000001 | 337 | | | +-------------------+----------+--------------+------------------+ 1 row in set (0.00 sec) mysql> SHOW BINLOG EVENTS IN ‘master-bin.000001‘; +-------------------+-----+-------------+-----------+-------------+----------------------------------------------------------------------------------+ | Log_name | Pos | Event_type | Server_id | End_log_pos | Info | +-------------------+-----+-------------+-----------+-------------+----------------------------------------------------------------------------------+ | master-bin.000001 | 4 | Format_desc | 1 | 107 | Server ver: 5.5.28-log, Binlog ver: 4 | | master-bin.000001 | 107 | Query | 1 | 262 | GRANT REPLICATION SLAVE ON *.* TO ‘repuser‘@‘172.16.%.%‘ IDENTIFIED BY ‘repuser‘ | | master-bin.000001 | 262 | Query | 1 | 337 | FLUSH PRIVILEGES | +-------------------+-----+-------------+-----------+-------------+----------------------------------------------------------------------------------+ 3 rows in set (0.02 sec) mysql> \q Bye 再在Slave上启动复制功能 [root@Slave mysql]# mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 2 Server version: 5.5.28 MySQL Community Server (GPL) Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the buffer. mysql> CHANGE MASTER TO MASTER_HOST=‘172.16.1.101‘,MASTER_PORT=3306,MASTER_USER=‘repuser‘,MASTER_PASSWORD=‘repuser‘,MASTER_LOG_FILE=‘master-bin.000001‘,MASTER_LOG_POS=337; Query OK, 0 rows affected (0.18 sec) mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Master_Host: 172.16.1.101 Master_User: repuser Master_Port: 3306 Connect_Retry: 60 Master_Log_File: master-bin.000001 Read_Master_Log_Pos: 337 Relay_Log_File: relay-log.000001 Relay_Log_Pos: 4 Relay_Master_Log_File: master-bin.000001 Slave_IO_Running: No Slave_SQL_Running: No Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 337 Relay_Log_Space: 107 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: NULL Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 0 1 row in set (0.00 sec) mysql> START SLAVE; Query OK, 0 rows affected (0.49 sec) mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.16.1.101 Master_User: repuser Master_Port: 3306 Connect_Retry: 60 Master_Log_File: master-bin.000001 Read_Master_Log_Pos: 337 Relay_Log_File: relay-log.000002 Relay_Log_Pos: 254 Relay_Master_Log_File: master-bin.000001 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 337 Relay_Log_Space: 404 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 1 row in set (0.04 sec)
4、测试复制功能
首先在主节点上创建一个测试库 [root@Master mysql]# mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 5 Server version: 5.5.28-log MySQL Community Server (GPL) Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the buffer. mysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | test | +--------------------+ 4 rows in set (0.28 sec) mysql> CREATE DATABASE mydb; Query OK, 1 row affected (0.10 sec) mysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | mydb | | mysql | | performance_schema | | test | +--------------------+ 5 rows in set (0.01 sec) 再在从节点上查看是否有此库 [root@Slave mysql]# mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 6 Server version: 5.5.28 MySQL Community Server (GPL) Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the buffer. mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.16.1.101 Master_User: repuser Master_Port: 3306 Connect_Retry: 60 Master_Log_File: master-bin.000001 Read_Master_Log_Pos: 420 # 可以看到已经读取到420位置了 Relay_Log_File: relay-log.000002 Relay_Log_Pos: 337 Relay_Master_Log_File: master-bin.000001 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 420 # 同样执行到了420位置 Relay_Log_Space: 487 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 1 row in set (0.01 sec) mysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | mydb | | mysql | | performance_schema | | test | +--------------------+ 5 rows in set (0.00 sec) 可以看到主从复制效果已然实现 查看从节点的错误日志，发现复制相关的日志信息也会记录到错误日志中 [root@Slave mysql]# tail /mydata/data/Slave.err 160115 15:55:06 InnoDB: 1.1.8 started; log sequence number 0 160115 15:55:07 [Note] Server hostname (bind-address): ‘0.0.0.0‘; port: 3306 160115 15:55:07 [Note] - ‘0.0.0.0‘ resolves to ‘0.0.0.0‘; 160115 15:55:07 [Note] Server socket created on IP: ‘0.0.0.0‘. 160115 15:55:08 [Note] Event Scheduler: Loaded 0 events 160115 15:55:08 [Note] /usr/local/mysql/bin/mysqld: ready for connections. Version: ‘5.5.28‘ socket: ‘/tmp/mysql.sock‘ port: 3306 MySQL Community Server (GPL) 160115 16:05:15 [Note] ‘CHANGE MASTER TO executed‘. Previous state master_host=‘‘, master_port=‘3306‘, master_log_file=‘‘, master_log_pos=‘4‘. New state master_host=‘172.16.1.101‘, master_port=‘3306‘, master_log_file=‘master-bin.000001‘, master_log_pos=‘337‘. 160115 16:10:46 [Note] Slave I/O thread: connected to master ‘repuser@172.16.1.101:3306‘,replication started in log ‘master-bin.000001‘ at position 337 160115 16:10:46 [Note] Slave SQL thread initialized, starting replication in log ‘master-bin.000001‘ at position 337, relay log ‘./relay-log.000001‘ position: 4
四、MySQL5.5半同步复制的实现
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原文地址：http://soysauce93.blog.51cto.com/7589461/1735321
