MySQL5.7主从从配置
主从从，也称为级联主从，数据流向：A(主)->B(从)->C(从从)，主从从级联复制。
应用场景
- 在主从配置的基础上，再增加一个从库，进一步提高数据安全，容灾备份。
- 读写分离，从库只用于查询，提高数据库整体性能。
- 从从库，用于备份，等同在线实时增量备份。
部署环境
注：使用docker部署mysql实例，方便快速搭建演示环境。但本文重点是讲解主从配置，因此简略描述docker环境构建mysql容器实例。
- 数据库：MySQL 5.7.x （相比5.5，5.6而言，5.7同步性能更好，支持多源复制，可实现多主一从，主从库版本应保证一致）
- 操作系统：CentOS 7.x
- 容器：Docker 17.09.0-ce
- 镜像：mysql:5.7
- 主库：IP=192.168.10.212; PORT=4200; server-id=200; database=test; table=user
- 从库：IP=192.168.10.212; PORT=4211; server-id=210; database=test; table=user
- 从从库：IP=192.168.10.212; PORT=4211; server-id=211; database=test; table=userk
配置约束
- 主从库必须保证网络畅通可访问
- 主库必须开启binlog日志
- 主从库的server-id必须不同
事前准备
- 关闭selinux
setenforce 0
vim /etc/sysconfig/selinux
SELINUX=disabled
# 若不关闭，使用docker启动mysql5.7镜像容器时启动不起来，查看日志会有如下错误显示： ERROR: mysqld failed while attempting to check config command was: "mysqld --verbose --help" mysqld: Can't read dir of '/etc/mysql/conf.d/' (Errcode: 13 - Permission denied) mysqld: [ERROR] Fatal error in defaults handling. Program aborted! ERROR: mysqld failed while attempting to check config command was: "mysqld --verbose --help" mysqld: Can't read dir of '/etc/mysql/conf.d/' (Errcode: 13 - Permission denied) mysqld: [ERROR] Fatal error in defaults handling. Program aborted! - 安装并启动docker
yum install epel-release
yum -y install docker
systemctl start docker.service
- 创建目录
mkdir -p /datavol/mysql-200/{mysql,conf}
mkdir -p /datavol/mysql-210/{mysql,conf}
mkdir -p /datavol/mysql-211/{mysql,conf}
【主库】操作及配置
把该文件放到主库所在配置文件路径下：/datavol/mysql-200/conf
配置my.cnf
[client] port = 3306 default-character-set = utf8mb4 [mysql] port = 3306 default-character-set = utf8mb4 [mysqld] ########################## # summary ########################## #bind-address = 0.0.0.0 #port = 3306 #datadir=/datavol/mysql/data #数据存储目录 ########################## # log bin ########################## server-id = 200 #必须唯一 log_bin = mysql-bin #开启及设置二进制日志文件名称 binlog_format = MIXED sync_binlog = 1 expire_logs_days =7 #二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。 #binlog_cache_size = 128m #max_binlog_cache_size = 512m #max_binlog_size = 256M binlog-do-db = test #要同步的数据库 binlog-ignore-db = mysql #不需要同步的数据库 binlog_ignore_db = information_schema binlog_ignore_db = performation_schema binlog_ignore_db = sys ########################## # character set ########################## character-set-server = utf8mb4 collation-server = utf8mb4_unicode_ci 安装启动主库
[root@localhost ~]# docker run -d -p 4200:3306 --name=mysql-200 -v /datavol/mysql-200/conf:/etc/mysql/conf.d -v /datavol/mysql-200:/datavol/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7 5691bac538e646db00273e3cad5b350dbe6cce0bd176346b7eefd9a6f9e3a9ad [root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 5691bac538e6 mysql:5.7 "docker-entrypoint..." 44 seconds ago Up 43 seconds 33060/tcp, 0.0.0.0:4200->3306/tcp mysql-200 [root@localhost ~]# docker exec -it mysql-200 /bin/bash root@5691bac538e6:/# mysql -u root -p Enter password: 注：若不熟悉docker，可使用传统方式安装mysql，效果相同。
创建授权用户
连接mysql主数据库，键入命令mysql -u root -p，输入密码后登录数据库。创建用户用于从库同步复制，授予复制、同步访问的权限
mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456'; Query OK, 0 rows affected (0.01 sec) mysql> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%'; Query OK, 0 rows affected (0.00 sec) log_bin是否开启
mysql> show variables like 'log_bin'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | ON | +---------------+-------+ 1 row in set 查看master状态
mysql> show master status;
+------------------+----------+--------------+--------------------------------------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------------+----------+--------------+--------------------------------------------------+-------------------+ | mysql-bin.000001 | 154 | test | mysql,information_schema,performation_schema,sys | | +------------------+----------+--------------+--------------------------------------------------+-------------------+ 1 row in set 【从库】配置及操作
配置my.cnf
把该文件放到主库所在配置文件路径下：/datavol/mysql-210/conf/
[client] port = 3306 default-character-set = utf8mb4 [mysql] port = 3306 default-character-set = utf8mb4 [mysqld] ########################## # summary ########################## #bind-address = 0.0.0.0 #port = 3306 #datadir=/datavol/mysql/data #数据存储目录 ########################## # log bin ########################## server-id = 210 #必须唯一 log_bin = mysql-bin #开启及设置二进制日志文件名称 binlog_format = MIXED sync_binlog = 1 expire_logs_days =7 #二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。 log_slave_updates = 1 #【关键点】从主服务器接收到的更新同时要写入二进制日志 #binlog_cache_size = 128m #max_binlog_cache_size = 512m #max_binlog_size = 256M binlog-do-db = test #要同步的数据库 binlog-ignore-db = mysql #不需要同步的数据库 binlog_ignore_db = information_schema binlog_ignore_db = performation_schema binlog_ignore_db = sys ########################## # character set ########################## character-set-server = utf8mb4 collation-server = utf8mb4_unicode_ci **log_slave_updates = 1 ** #【关键点】从主服务器接收到的更新同时要写入二进制日志
启动前确认slave账号在备库服务器上，是否能够正常连接主库，检查权限。
命令：mysql -h 主库ip -u slave -p；输入密码确认登录情况；
安装启动从库
[root@localhost ~]# docker run -d -p 4210:3306 --name=mysql-210 -v /datavol/mysql-210/conf:/etc/mysql/conf.d -v /datavol/mysql-210:/datavol/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7 19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7 [root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 19e93b6d93ca mysql:5.7 "docker-entrypoint..." 4 seconds ago Up 3 seconds 33060/tcp, 0.0.0.0:4210->3306/tcp mysql-210 [root@localhost ~]# docker exec -it mysql-210 /bin/bash root@19e93b6d93ca:/# mysql -u root -p Enter password: 设置主库200信息
登录【从数据库】，进入mysql命令行。
mysql> stop slave;
Query OK, 0 rows affected
mysql> CHANGE MASTER TO
MASTER_HOST='192.168.10.212',
MASTER_PORT=4200,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000001',
MASTER_LOG_POS=154;
Query OK, 0 rows affected
mysql> start slave;
Query OK, 0 rows affected
stop slave; //停止同步
start slave; //开始同步
//必须和【主数据库】的信息匹配。
CHANGE MASTER TO
MASTER_HOST='192.168.10.212', //主库IP
MASTER_PORT=4200, //主库端口
MASTER_USER='slave', //访问主库且有同步复制权限的用户
MASTER_PASSWORD='123456', //登录密码
//【关键处】从主库的该log_bin文件开始读取同步信息，主库show master status返回结果
MASTER_LOG_FILE='mysql-bin.000001',
//【关键处】从文件中指定位置开始读取，主库show master status返回结果
MASTER_LOG_POS=154;
查看同步状态
mysql> show slave status \G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.10.212 Master_User: slave Master_Port: 4200 Connect_Retry: 60 Master_Log_File: mysql-bin.000003 Read_Master_Log_Pos: 617 Relay_Log_File: 5f0d9861bcb1-relay-bin.000002 Relay_Log_Pos: 320 Relay_Master_Log_File: mysql-bin.000003 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: 617 Relay_Log_Space: 534 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: 200 Master_UUID: b6df98cf-e71f-11e8-9987-0242ac110007 Master_Info_File: /var/lib/mysql/master.info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) 只有【Slave_IO_Running】和【Slave_SQL_Running】都是Yes，则同步是正常的。
如果是No或者Connecting都不行，可查看mysql-error.log，以排查问题。
mysql> show variables like 'log_error%'; +---------------------+--------+ | Variable_name | Value | +---------------------+--------+ | log_error | stderr | | log_error_verbosity | 3 | +---------------------+--------+ 2 rows in set 配置完成，则主从数据库开始自动同步。此外，【从库】相当于【从从库】的主库，也需要设置账号及同步权限。
创建授权用户
创建用户用于从库同步复制，授予复制、同步访问的权限
mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456'; Query OK, 0 rows affected (0.01 sec) mysql> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%'; Query OK, 0 rows affected (0.00 sec) log_bin是否开启
mysql> show variables like 'log_bin'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | ON | +---------------+-------+ 1 row in set 查看master状态
mysql> show master status;
+------------------+----------+--------------+--------------------------------------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------------+----------+--------------+--------------------------------------------------+-------------------+ | mysql-bin.000003 | 617 | test | mysql,information_schema,performation_schema,sys | | +------------------+----------+--------------+--------------------------------------------------+-------------------+ 1 row in set 【从从库】配置及操作
配置my.cnf
把该文件放到主库所在配置文件路径下：/datavol/mysql-211/conf/
[client]
port = 3306 default-character-set = utf8mb4 [mysql] port = 3306 default-character-set = utf8mb4 [mysqld] ########################## # summary ########################## #bind-address = 0.0.0.0 #port = 3306 #datadir=/datavol/mysql/data #数据存储目录 ########################## # log bin ########################## server-id = 211 ########################## # character set ########################## character-set-server = utf8mb4 collation-server = utf8mb4_unicode_ci 安装启动从从库
[root@localhost ~]# docker run -d -p 4211:3306 --name=mysql-211 -v /datavol/mysql-211/conf:/etc/mysql/conf.d -v /datavol/mysql-211:/datavol/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7 19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7 [root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 19e93b6d93ca mysql:5.7 "docker-entrypoint..." 4 seconds ago Up 3 seconds 33060/tcp, 0.0.0.0:4211->3306/tcp mysql-211 [root@localhost ~]# docker exec -it mysql-211 /bin/bash root@19e93b6d93ca:/# mysql -u root -p Enter password: 设置从库210信息
登录【从数据库】，进入mysql命令行。
mysql> stop slave;
Query OK, 0 rows affected
mysql> CHANGE MASTER TO MASTER_HOST='192.168.10.212',
MASTER_PORT=4210,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=617;
Query OK, 0 rows affected
mysql> start slave;
Query OK, 0 rows affected
stop slave; //停止同步
start slave; //开始同步
//必须和【主数据库】的信息匹配。
CHANGE MASTER TO
MASTER_HOST='192.168.10.212', //主库IP
MASTER_PORT=4210, //主库端口(在这里是指从库)
MASTER_USER='slave', //访问主库且有同步复制权限的用户
MASTER_PASSWORD='123456', //登录密码
//【关键处】从主库的该log_bin文件开始读取同步信息，重启mysql服务后，主库show master status返回结果，
MASTER_LOG_FILE='mysql-bin.000003',
//【关键处】从文件中指定位置开始读取，重启mysql服务后，主库show master status返回结果，重新取值
MASTER_LOG_POS=617;
查看同步状态
mysql> show slave status \G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.10.212 Master_User: slave Master_Port: 4210 Connect_Retry: 60 Master_Log_File: mysql-bin.000003 Read_Master_Log_Pos: 617 Relay_Log_File: a3d52e314640-relay-bin.000002 Relay_Log_Pos: 783 Relay_Master_Log_File: mysql-bin.000003 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: 617 Relay_Log_Space: 997 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: 210 Master_UUID: 088c2c93-e720-11e8-8e80-0242ac110009 Master_Info_File: /var/lib/mysql/master.info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) 只有【Slave_IO_Running】和【Slave_SQL_Running】都是Yes，则同步是正常的。
如果是No或者Connecting都不行，可查看mysql-error.log，以排查问题。
mysql> show variables like 'log_error%'; +---------------------+--------+ | Variable_name | Value | +---------------------+--------+ | log_error | stderr | | log_error_verbosity | 3 | +---------------------+--------+ 2 rows in set 配置完成，则从从数据库开始自动同步。
验证数据同步
建库
使用root账号登录【主服务器】，创建test数据库
mysql> CREATE DATABASE test; Query OK, 1 row affected (0.00 sec) mysql> USE test; Database changed 建表
在【主库】中创建user表
CREATE TABLE `user` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `name` varchar(20) COLLATE utf8mb4_unicode_ci NOT NULL, `age` tinyint(3) unsigned NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci; 新增
在【主库】中向user表插入一条数据：
mysql> use test; Database changed mysql> INSERT INTO user (id, name, age) VALUES (1, '张三', 18); Database changed mysql> SELECT * FROM user; +----+------+-----+ | id | name | age | +----+------+-----+ | 1 | 张三 | 18 | +----+------+-----+ 1 row in set 在【从库】及【从从库】中查询user表数据：
mysql> use test; Database changed mysql> SELECT * FROM user; +----+------+-----+ | id | name | age | +----+------+-----+ | 1 | 张三 | 18 | +----+------+-----+ 1 row in set 新增记录同步成功。
更新
在【主库】中修改刚才插入的数据：
mysql> UPDATE user SET name='李四' where id=1; Database changed Rows matched: 1 Changed: 1 Warnings: 0 mysql> SELECT * FROM user; +----+------+-----+ | id | name | age | +----+------+-----+ | 1 | 李四 | 18 | +----+------+-----+ 1 row in set 在【从库】及【从从库】中查询user表数据：
mysql> SELECT * FROM user;
+----+------+-----+
| id | name | age | +----+------+-----+ | 1 | 李四 | 18 | +----+------+-----+ 1 row in set 更新记录同步成功。
删除
在【主库】中删除刚才更新的数据：
mysql> DELETE FROM user WHERE id=1; Database changed mysql> SELECT * FROM user; Empty set 在【从库】及【从从库】中查询user表数据：
mysql> SELECT * FROM user; Empty set 删除记录同步成功。
补充：
- 如果【主服务器】重启mysql服务，【从服务器】会等待与【主服务器】重连。当主服务器恢复正常后，从服务器会自动重新连接上主服务器，并正常同步数据。
- 如果某段时间内，【从数据库】服务器异常导致同步中断（可能是同步点位置不匹配），可以尝试以下恢复方法：进入【主数据库】服务器（正常），在bin-log中找到【从数据库】出错前的position，然后在【从数据库】上执行change master，将master_log_file和master_log_pos重新指定后，开始同步。
- 以上为参考：
- 实际搭建环境为window服务器器，my.ini的配置如下：搭建主从负载前,主、备服务器，已建数据库efb，经过测试可以实现主从复制。
- master示例：
-
###### CLIENT SECTION ###### # The following options will be read by MySQL client applications. # Note that only client applications shipped by MySQL are guaranteed # to read this section. If you want your own MySQL client program to # honor these values, you need to specify it as an option during the # MySQL client library initialization. [client] port=3306 [mysql] default-character-set=utf8 ###### SERVER SECITON ###### # The following options will be read by the MySQL Server. Make sure that # you have installed the server correctly (see above) so it reads this # file. [mysqld] #skip-grant-tables # The TCP/IP Port the MySQL Server will listen on port = 3306 #Path to installation directory. All paths are usually resolved relative to this. basedir=D:\Program Files\mysql-5.7.26-winx64 #Path to the database root datadir=D:\Program Files\mysql-5.7.26-winx64\data # The default character set that will be used when a new schema or table is # created and no character set is defined character-set-server=utf8 # The maximum amount of concurrent sessions the MySQL server will # allow. One of these connections will be reserved for a user with # SUPER privileges to allow the administrator to login even if the # connection limit has been reached. max_connections=200 bind-address=0.0.0.0 # The default storage engine that will be used when create new tables when default-storage-engine=INNODB # Set the SQL mode to strict sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES # 慢查询时间 超过3秒则为慢查询 slow_query_log = 1 long_query_time = 3 slow-query-log-file = D:\Program Files\mysql-5.7.26-winx64\log\mysql-slow.log # 错误日志路径 log_error = D:\Program Files\mysql-5.7.26-winx64\log\mysql-error.log ###### 主从配置 MASTER-SLAVE ###### # 节点ID，确保唯一 server-id = 885 #开启mysql的binlog日志功能 log-bin = mysql-bin #控制数据库的binlog刷到磁盘上去 , 0 不控制，性能最好，1每次事物提交都会刷到日志文件中，性能最差，最安全 sync_binlog = 1 #binlog日志格式，mysql默认采用statement，建议使用mixed binlog_format = mixed #binlog过期清理时间 expire_logs_days = 30 #binlog每个日志文件大小 max_binlog_size = 1000m #binlog缓存大小 binlog_cache_size = 4m #最大binlog缓存大 max_binlog_cache_size= 512m #要同步的数据库 binlog-do-db = efb #不生成日志文件的数据库，多个忽略数据库可以用逗号拼接，或者 复制这句话，写多行 binlog-ignore-db=mysql binlog_ignore_db = information_schema binlog_ignore_db = performation_schema binlog_ignore_db = sys # 自增值的偏移量 auto-increment-offset = 1 # 自增值的自增量 auto-increment-increment = 1 #跳过从库错误 slave-skip-errors = all
slave示例：
[client] port = 3306 default-character-set=utf8 [mysql] port = 3306 default-character-set=utf8 [mysqld] port = 3306 character-set-server=utf8 basedir=D:\Program Files\mysql-5.7.26-winx64 datadir=D:\Program Files\mysql-5.7.26-winx64\data max_connections=200 default-storage-engine=INNODB sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES ###slave### server-id = 890 #必须唯一 log_bin = mysql-bin #开启及设置二进制日志文件名称 binlog_format = MIXED sync_binlog = 1 expire_logs_days =7 #二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。 log_slave_updates = 1 #【关键点】从主服务器接收到的更新同时要写入二进制日志 #binlog_cache_size = 128m #max_binlog_cache_size = 512m #max_binlog_size = 256M binlog-do-db = efb #要同步的数据库 binlog-ignore-db = mysql #不需要同步的数据库 binlog_ignore_db = information_schema binlog_ignore_db = performation_schema binlog_ignore_db = sys