参考
http://imysql.com/tag/gtid
http://mysqllover.com/?p=594
Mysql 基于GTID的主从复制及切换
一、主从复制配置
两个mysql服务的my.cnf 中相关内容配置
[mysqld]
#从复制数据库表设置
replicate-wild-ignore-table = mysql.%,information_schema.%,innodb.%,innodb_log.%,performance_schema.%,test.%,tmp.% #复制时忽略数据库及表
#my.cnf 开启gtid
log_slave_updates # 表示即可以当从也可以当主
gtid_mode = on
enforce-gtid-consistency = true
10.123.2.128 my.cnf
[mysqld]
server_id=10128 # 所有 mysql服务保持各不相同
10.123.2.165 my.cnf
[mysqld]
server_id=10165 # 所有 mysql服务保持各不相同
# 验证gtid已开启
mysql> SHOW VARIABLES like ‘%gtid%‘;
+--------------------------+-----------+
| Variable_name | Value |
+--------------------------+-----------+
| enforce_gtid_consistency | ON |
| gtid_executed | |
| gtid_mode | ON |
| gtid_next | AUTOMATIC |
| gtid_owned | |
| gtid_purged | |
+--------------------------+-----------+
# 查看当前mysql服务的uuid,gtid的主从同步,绝大多数功能基于server_uuid
mysql> SHOW VARIABLES like ‘%server_uuid%‘;
ip: 10.235.2.128
server_uuid: aad2226a-6ed3-11e4-9ae0-080027cdcda2
ip: 10.235.2.165
server_uuid: 68a061ee-b013-11e4-845a-080027a36fd3
分别在10.235.2.128、10.235.2.165两个 mysql服务中添加 zabbix_repl用户同步权限
mysql> grant Replication client,replication slave on *.* to ‘zabbix_repl‘@‘%‘ identified by ‘123456‘;flush privileges;
10.235.2.165 的mysql服务中设置主mysql信息,其中的master_auto_position=1 参数会自动判断从主的什么位置同步数据
mysql> stop slave;
mysql> change master to MASTER_HOST=‘10.235.2.128‘,master_user=‘zabbix_repl‘,master_password=‘123456‘,MASTER_PORT = 3306,MASTER_CONNECT_RETRY = 60,master_auto_position=1;
mysql> start slave;
mysql> show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 10.235.2.128
Master_User: zabbix_repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 551
Relay_Log_File: relay-log.000002
Relay_Log_Pos: 761
Relay_Master_Log_File: mysql-bin.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
...
...
...
Master_Server_Id: 10128
Master_UUID: aad2226a-6ed3-11e4-9ae0-080027cdcda2 # 主数据库的server_uuid
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 the slave I/O thread to update it
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: aad2226a-6ed3-11e4-9ae0-080027cdcda2:1-2 # 记录了relay日志从Master获取了binlog日志的位置的gtid,由master_uuid:事务id组成
Executed_Gtid_Set: 68a061ee-b013-11e4-845a-080027a36fd3:1-3, # 本机binlog执行位置的gtid,由 server_uuid:事务id 组成
aad2226a-6ed3-11e4-9ae0-080027cdcda2:1-2 # 主服务上binlog执行位置的gtid,由 master_uuid:事务id 组成
Auto_Position: 1
在10.235.2.128的主mysql中添加数据测试
mysql> create database test2;
mysql> show master status \G
*************************** 1. row ***************************
File: mysql-bin.000001
Position: 1014
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set: aad2226a-6ed3-11e4-9ae0-080027cdcda2:1-4
再次查看10.235.2.165从mysql同步状态,同步正常
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| innodb |
| innodb_log |
| mysql |
| performance_schema |
| test |
| test2 | # 新添加的测试库
| testdb1 |
| tmp |
+--------------------+
mysql> show slave status \G
*************************** 1. row ***************************
...
...
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
...
...
Master_UUID: aad2226a-6ed3-11e4-9ae0-080027cdcda2
...
...
Retrieved_Gtid_Set: aad2226a-6ed3-11e4-9ae0-080027cdcda2:1-4
Executed_Gtid_Set: 68a061ee-b013-11e4-845a-080027a36fd3:1-3,
aad2226a-6ed3-11e4-9ae0-080027cdcda2:1-4
Auto_Position: 1
二、主从切换
在10.235.2.165主机
mysql> stop slave;
在10.235.2.128主机
mysql> stop slave;
mysql> change master to MASTER_HOST=‘10.235.2.165‘,master_user=‘zabbix_repl‘,master_password=‘123456‘,MASTER_PORT = 3306,MASTER_CONNECT_RETRY = 60,master_auto_position=1;
mysql> start slave;
mysql> show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 10.235.2.165
Master_User: zabbix_repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 1529
Relay_Log_File: relay-log.000002
Relay_Log_Pos: 888
Relay_Master_Log_File: mysql-bin.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
...
...
Master_UUID: 68a061ee-b013-11e4-845a-080027a36fd3
...
...
Retrieved_Gtid_Set: 68a061ee-b013-11e4-845a-080027a36fd3:1-3
Executed_Gtid_Set: 68a061ee-b013-11e4-845a-080027a36fd3:1-3 # 一般与master mysql 10.235.2.165mysql的gtid相同
Auto_Position: 1
mysql>
在10.235.2.165主机
mysql> show master status \G
*************************** 1. row ***************************
File: mysql-bin.000001
Position: 1529
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set: 68a061ee-b013-11e4-845a-080027a36fd3:1-3, # 10.235.2.165 mysql的gtid
aad2226a-6ed3-11e4-9ae0-080027cdcda2:1-4
在10.235.2.165测试删除数据
mysql> drop database test2;
Query OK, 0 rows affected (0.12 sec)
在10.235.2.128查看数据已经同步(已经没有数据库test2)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| innodb |
| innodb_log |
| mysql |
| performance_schema |
| test |
| testdb1 |
| tmp |
+--------------------+
到这里主机切换已经完成
三、主主复制
原理:
1、双方节点都得有创建具有复制权限的用户 # 参考一、主从复制 添加权限用户
2、双方都得启用中继日志和二进制日志
3、为保证具有自动增长功能的字段能正确生成ID,需要配置两个节点分别使用偶数或奇数ID号
4、都要把对方配置为自己的主节点 # 参考一、主从复制 change master to ...
在my.cnf添加下面相关配置
10.235.2.165 my.cnf配置
[mysqld]
auto-increment-offset = 1 #自增id为奇数
auto-increment-increment = 2 #自增id的增量
log_slave_updates # 表示即可以当从也可以当主
10.235.2.128 my.cnf配置
[mysqld]
auto-increment-offset = 2 #自增id为偶数
auto-increment-increment = 2 #自增id的增量
log_slave_updates # 表示即可以当从也可以当主
四、GTID主从复制遇到的异常情况
错误1:
当备库复制出错时,传统的跳过错误的方法是设置sql_slave_skip_counter,然后再START SLAVE。
但如果打开了GTID,就会设置失败:
mysql> set global sql_slave_skip_counter = 1;
ERROR 1858 (HY000): sql_slave_skip_counter can not be set when the server is running with @@GLOBAL.GTID_MODE = ON. Instead, for each transaction that you want to skip, generate an empty transaction with the same GTID as the transaction
提示的错误信息告诉我们,可以通过生成一个空事务来跳过错误的事务。
我们手动产生一个备库复制错误:
Last_SQL_Error: Error ‘Unknown table ‘test.t1” on query. Default database: ‘test’. Query: ‘DROP TABLE `t1` /* generated by server */’
查看binlog中,该DDL对应的GTID为7a07cd08-ac1b-11e2-9fcf-0010184e9e08:1131
在备库上执行:
mysql> STOP SLAVE;
Query OK, 0 rows affected (0.00 sec)
mysql> SET SESSION GTID_NEXT = ‘7a07cd08-ac1b-11e2-9fcf-0010184e9e08:1131‘;
Query OK, 0 rows affected (0.00 sec)
mysql> BEGIN; COMMIT;
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql> SET SESSION GTID_NEXT = AUTOMATIC;
Query OK, 0 rows affected (0.00 sec)
mysql> START SLAVE;
再查看show slave status,就会发现错误事务已经被跳过了。这种方法的原理很简单,空事务产生的GTID加入到GTID_EXECUTED中,这相当于告诉备库,这个GTID对应的事务已经执行了。