多主一從，也稱為多源復制，數據流向：
- 主庫1 -> 從庫s
- 主庫2 -> 從庫s
- 主庫n -> 從庫s
應用場景
- 數據匯總，可將多個主數據庫同步匯總到一個從數據庫中，方便數據統計分析。
- 讀寫分離，從庫只用於查詢，提高數據庫整體性能。
部署環境
注：使用docker部署mysql實例，方便快速搭建演示環境。但本文重點是講解主從配置，因此簡略描述docker環境構建mysql容器實例。
- 數據庫：MySQL 5.7.x （相比5.5，5.6而言，5.7同步性能更好，支持多源復制，可實現多主一從，主從庫版本應保證一致）
- 操作系統：CentOS 7.x
- 容器：Docker 17.09.0-ce
- 鏡像：mysql:5.7
- 主庫300：IP=192.168.10.212; PORT=4300; server-id=300; database=test3; table=user
- 主庫400：IP=192.168.10.212; PORT=4400; server-id=400; database=test4; table=user
- 主庫500：IP=192.168.10.212; PORT=4500; server-id=500; database=test5; table=user
- 從庫10345：IP=192.168.10.212; PORT=4345; server-id=10345; database=test3,test4,test5; table=user
配置約束
- 主從庫必須保證網絡暢通可訪問
- 主庫必須開啟binlog日志
- 主從庫的server-id必須不同
事前准備
- 關閉selinux
setenforce 0
vim /etc/sysconfig/selinux
SELINUX=disabled
# 若不關閉，使用docker啟動mysql5.7鏡像容器時啟動不起來，查看日志會有如下錯誤顯示：
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!
- 安裝並啟動docker
yum install epel-release
yum -y install docker
systemctl start docker.service
- 創建目錄
mkdir -p /datavol/mysql-300/{mysql,conf}
mkdir -p /datavol/mysql-400/{mysql,conf}
mkdir -p /datavol/mysql-500/{mysql,conf}
mkdir -p /datavol/mysql-10345/{mysql,conf}
【主庫300】操作及配置
配置my.cnf
把該文件放到主庫所在配置文件路徑下：/datavol/mysql-300/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 #數據存儲目錄
##########################
# log bin
##########################
server-id = 300 #必須唯一
log_bin = mysql-bin #開啟及設置二進制日志文件名稱
binlog_format = MIXED
sync_binlog = 1
expire_logs_days =7 #二進制日志自動刪除/過期的天數。默認值為0，表示不自動刪除。
#binlog_cache_size = 128m
#max_binlog_cache_size = 512m
#max_binlog_size = 256M
binlog-do-db = test3 #要同步的數據庫
binlog-ignore-db = mysql #不需要同步的數據庫
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
安裝啟動
[root@localhost ~]# docker run -d -p 4300:3306 --name=mysql-300 -v /datavol/mysql-300/conf:/etc/mysql/conf.d -v /datavol/mysql-300/mysql:/var/lib/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, 0.0.0.0:4300->3306/tcp mysql-300
[root@localhost ~]# docker exec -it mysql-300 /bin/bash
root@5691bac538e6:/# mysql -u root -p
Enter password:
注：若不熟悉docker，可使用傳統方式安裝mysql，效果相同。
創建授權用戶
連接mysql主數據庫，鍵入命令mysql -u root -p，輸入密碼后登錄數據庫。創建用戶用於從庫同步復制，授予復制、同步訪問的權限
mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)
mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
log_bin是否開啟
mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin | ON |
+---------------+-------+
1 row in set
查看master狀態
mysql> show master status \G
*************************** 1. row ***************************
File: mysql-bin.000003
Position: 438
Binlog_Do_DB: test3
Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys
【主庫400】配置及操作
配置my.cnf
把該文件放到主庫所在配置文件路徑下：/datavol/mysql-400/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 #數據存儲目錄
##########################
# log bin
##########################
server-id = 400 #必須唯一
log_bin = mysql-bin #開啟及設置二進制日志文件名稱
binlog_format = MIXED
sync_binlog = 1
expire_logs_days =7 #二進制日志自動刪除/過期的天數。默認值為0，表示不自動刪除。
#binlog_cache_size = 128m
#max_binlog_cache_size = 512m
#max_binlog_size = 256M
binlog-do-db = test4 #要同步的數據庫
binlog-ignore-db = mysql #不需要同步的數據庫
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
安裝啟動
[root@localhost ~]# docker run -d -p 4400:3306 --name=mysql-400 -v /datavol/mysql-400/conf:/etc/mysql/conf.d -v /datavol/mysql-400/mysql:/var/lib/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, 0.0.0.0:4400->3306/tcp mysql-400
[root@localhost ~]# docker exec -it mysql-400 /bin/bash
root@19e93b6d93ca:/# mysql -u root -p
Enter password:
創建授權用戶
創建用戶用於從庫同步復制，授予復制、同步訪問的權限
mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)
mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
log_bin是否開啟
mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin | ON |
+---------------+-------+
1 row in set
查看master狀態
mysql> show master status \G;
*************************** 1. row ***************************
File: mysql-bin.000003
Position: 438
Binlog_Do_DB: test4
Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys
【主庫500】配置及操作
配置my.cnf
把該文件放到主庫所在配置文件路徑下：/datavol/mysql-500/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 #數據存儲目錄
##########################
# log bin
##########################
server-id = 500 #必須唯一
log_bin = mysql-bin #開啟及設置二進制日志文件名稱
binlog_format = MIXED
sync_binlog = 1
expire_logs_days =7 #二進制日志自動刪除/過期的天數。默認值為0，表示不自動刪除。
#binlog_cache_size = 128m
#max_binlog_cache_size = 512m
#max_binlog_size = 256M
binlog-do-db = test5 #要同步的數據庫
binlog-ignore-db = mysql #不需要同步的數據庫
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
安裝啟動
[root@localhost ~]# docker run -d -p 4500:3306 --name=mysql-500 -v /datavol/mysql-500/conf:/etc/mysql/conf.d -v /datavol/mysql-500/mysql:/var/lib/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, 0.0.0.0:4500->3306/tcp mysql-500
[root@localhost ~]# docker exec -it mysql-500 /bin/bash
root@19e93b6d93ca:/# mysql -u root -p
Enter password:
創建授權用戶
創建用戶用於從庫同步復制，授予復制、同步訪問的權限
mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)
mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
log_bin是否開啟
mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin | ON |
+---------------+-------+
1 row in set
查看master狀態
mysql> show master status \G
*************************** 1. row ***************************
File: mysql-bin.000003
Position: 438
Binlog_Do_DB: test5
Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys
【從庫10345】配置及操作
配置my.cnf
把該文件放到主庫所在配置文件路徑下：/datavol/mysql-10345/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 #數據存儲目錄
##########################
# log bin
##########################
server-id = 10345
master_info_repository = table
relay_log_info_repository = table
##########################
# character set
##########################
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
安裝啟動
[root@localhost ~]# docker run -d -p 4345:3306 --name=mysql-10345 -v /datavol/mysql-10345/conf:/etc/mysql/conf.d -v /datavol/mysql-10345/mysql:/var/lib/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, 0.0.0.0:4345->3306/tcp mysql-10345
[root@localhost ~]# docker exec -it mysql-10345 /bin/bash
root@19e93b6d93ca:/# mysql -u root -p
Enter password:
設置【主庫】信息
登錄【從庫10345】，進入mysql命令行。
mysql> stop slave;
Query OK, 0 rows affected
mysql> CHANGE MASTER TO
MASTER_HOST='192.168.10.212',
MASTER_PORT=4300,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=438
for channel '300';
Query OK, 0 rows affected
mysql> CHANGE MASTER TO
MASTER_HOST='192.168.10.212',
MASTER_PORT=4400,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=438
for channel '400';
Query OK, 0 rows affected
mysql> CHANGE MASTER TO
MASTER_HOST='192.168.10.212',
MASTER_PORT=4500,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=438
for channel '500';
Query OK, 0 rows affected
mysql> start slave;
Query OK, 0 rows affected
stop slave; //停止同步
start slave; //開始同步
//必須和【主庫】的信息匹配。
CHANGE MASTER TO
MASTER_HOST='192.168.10.212', //主庫IP
MASTER_PORT=4300, //主庫端口
MASTER_USER='slave', //訪問主庫且有同步復制權限的用戶
MASTER_PASSWORD='123456', //登錄密碼
//【關鍵處】從主庫的該log_bin文件開始讀取同步信息，主庫show master status返回結果
MASTER_LOG_FILE='mysql-bin.000003',
//【關鍵處】從文件中指定位置開始讀取，主庫show master status返回結果
MASTER_LOG_POS=438
**for channel '300'; //定義通道名稱 **
查看同步狀態
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: 4300
Connect_Retry: 60
Master_Log_File: mysql-bin.000003
Read_Master_Log_Pos: 1860
Relay_Log_File: 0ad84f013600-relay-bin-300.000002
Relay_Log_Pos: 1742
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: 1860
Relay_Log_Space: 1960
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: 300
Master_UUID: 4efae154-ebd4-11e8-bf7d-0242ac110007
Master_Info_File: mysql.slave_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: 300
Master_TLS_Version:
*************************** 2. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.10.212
Master_User: slave
Master_Port: 4400
Connect_Retry: 60
Master_Log_File: mysql-bin.000003
Read_Master_Log_Pos: 2461
Relay_Log_File: 0ad84f013600-relay-bin-400.000002
Relay_Log_Pos: 1187
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: 2461
Relay_Log_Space: 1405
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: 400
Master_UUID: 8fb0aa81-ebd4-11e8-ac5b-0242ac110009
Master_Info_File: mysql.slave_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: 400
Master_TLS_Version:
*************************** 3. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.10.212
Master_User: slave
Master_Port: 4500
Connect_Retry: 60
Master_Log_File: mysql-bin.000003
Read_Master_Log_Pos: 2151
Relay_Log_File: 0ad84f013600-relay-bin-500.000002
Relay_Log_Pos: 626
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: 2151
Relay_Log_Space: 844
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: 500
Master_UUID: b87704d2-ebd5-11e8-a90c-0242ac11000a
Master_Info_File: mysql.slave_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: 500
Master_TLS_Version:
3 rows in set (0.00 sec)
可以看見設置三個的主從同步通道的所有狀態信息。
只有【Slave_IO_Running】和【Slave_SQL_Running】都是Yes，則同步是正常的。
如果是No或者Connecting都不行，可查看mysql-error.log，以排查問題。
mysql> show variables like 'log_error%';
+---------------------+--------+
| Variable_name | Value |
+---------------------+--------+
| log_error | stderr |
| log_error_verbosity | 3 |
+---------------------+--------+
2 rows in set
配置完成，則【從庫10345】開始自動同步。
若需要單獨啟動或停止某個同步通道，可使用如下命令：
start slave for channel '300'; //啟動名稱為300的同步通道
stop slave for channel '300'; //停止名稱為300的同步通道
驗證數據同步
建庫
使用root賬號登錄【主庫300】，創建test3數據庫
mysql> CREATE DATABASE test3;
Query OK, 1 row affected (0.00 sec)
mysql> USE test3;
Database changed
建表
在【主庫300】中創建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【主庫300】中向user表插入一條數據：
mysql> use test3;
Database changed
mysql> INSERT INTO user (id, name, age) VALUES (300, 'Tom', 18);
Database changed
mysql> SELECT * FROM user;
+-----+------+-----+
| id | name | age |
+-----+------+-----+
| 300 | Tom | 18 |
+-----+------+-----+
1 row in set (0.00 sec)
在【從庫10345】中查詢user表數據：
mysql> use test3;
Database changed
mysql> SELECT * FROM user;
+-----+------+-----+
| id | name | age |
+-----+------+-----+
| 300 | Tom | 18 |
+-----+------+-----+
1 row in set (0.00 sec)
新增記錄同步成功。
更新
在【主庫300】中修改剛才插入的數據：
mysql> UPDATE user SET name='Peter' where id=300;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from user;
+-----+-------+-----+
| id | name | age |
+-----+-------+-----+
| 300 | Peter | 18 |
+-----+-------+-----+
1 row in set (0.00 sec)
在【從庫10345】中查詢user表數據：
mysql> select * from user;
+-----+-------+-----+
| id | name | age |
+-----+-------+-----+
| 300 | Peter | 18 |
+-----+-------+-----+
1 row in set (0.00 sec)
更新記錄同步成功。
刪除
在【主庫300】中刪除剛才更新的數據：
mysql> DELETE FROM user WHERE id=300;
Query OK, 1 row affected (0.00 sec)
mysql> select * from user;
Empty set (0.00 sec)
在【從庫10345】中查詢user表數據：
mysql> select * from user;
Empty set (0.00 sec)
刪除記錄同步成功。
注：【主庫400】、【主庫500】的驗證操作與上述類似。
補充：
- 如果【主服務器】重啟mysql服務，【從服務器】會等待與【主服務器】重連。當主服務器恢復正常后，從服務器會自動重新連接上主服務器，並正常同步數據。
- 如果某段時間內，【從數據庫】服務器異常導致同步中斷（可能是同步點位置不匹配），可以嘗試以下恢復方法：進入【主數據庫】服務器（正常），在bin-log中找到【從數據庫】出錯前的position，然后在【從數據庫】上執行change master，將master_log_file和master_log_pos重新指定后，開始同步。
- 若是不需要同步，登錄從庫執行：stop slave;
- 若需要單獨啟動或停止某個同步通道，可使用如下命令：
start slave for channel '300'; //啟動名稱為300的同步通道
stop slave for channel '300'; //停止名稱為300的同步通道 - 通常多主一從，主庫之間盡量不使用相同的databaseName，避免沖突。