更新时间:2022-09-18 08:12:05
1. 背景
* MySQL Replication默认都是异步(asynchronous),当主库在执行完一些事务后,是不会管备库的进度的。如果备库不幸落后,而更不幸的是主库此时又出现Crash(例如宕机),这时备库中的数据就是不完整的。简而言之,在主库发生故障的时候,我们无法使用备库来继续提供数据一致的服务了。
* Semi sync Replication在一定程度上保证提交的事务已经传给了至少一个备库。
* Semi sync Replication仅仅保证事务的已经传递到备库上,但是并不确保已经在备库上执行完成。
* Semi sync Replication主库等待超时(rpl_semi_sync_master_timeout)后,会自动降级为默认的异步(asynchronous)。
* MySQL 5.5版本开始支持Semi sync Replication
2. 环境
* master 服务器环境
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mysql> system cat /etc/redhat-release CentOS release 6.8 (Final) mysql> system ifconfig eth0 | sed -rn '2s#^.*addr:(.*) Bca.*$#\1#gp'
172.18.0.1 mysql> show variables like 'version' ;
+ ---------------+------------+
| Variable_name | Value | + ---------------+------------+
| version | 5.6.36-log | + ---------------+------------+
1 row in set (0.00 sec)
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* master 服务器环境
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mysql> system cat /etc/redhat-release CentOS release 6.8 (Final) mysql> system ifconfig eth0 | sed -rn '2s#^.*addr:(.*) Bca.*$#\1#gp'
172.18.4.1 mysql> show variables like 'version' ;
+ ---------------+------------+
| Variable_name | Value | + ---------------+------------+
| version | 5.6.36-log | + ---------------+------------+
1 row in set (0.00 sec)
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* master服务器my.cnf配置文件
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[mysqld] ########basic settings######## # 主从server-id一定要设置不同 server- id = 110
port = 3306 user = mysql bind_address = 0.0.0.0 character_set_server=utf8mb4 skip_name_resolve = 1 datadir = /data/mysql_data
log_error = error.log #######replication settings######## master_info_repository = TABLE relay_log_info_repository = TABLE # MySQL复制是基于binlog日志的 log_bin = bin.log sync_binlog = 1 log_slave_updates # MySQL binlog格式搭建主从时必须设置为row binlog_format = row relay_log = relay.log relay_log_recovery = 1 slave_skip_errors = ddl_exist_errors ######semi sync replication settings######## # 设置插件目录路径 plugin_dir= /usr/local/mysql/lib/plugin
# 加载插件 plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
# 开启master semi sync replication loose_rpl_semi_sync_master_enabled = 1 # 开启slave semi sync replication loose_rpl_semi_sync_slave_enabled = 1 # 等待5秒无ack应答自动切换为异步模式 loose_rpl_semi_sync_master_timeout = 5000 |
* slave服务器my.cnf配置文件
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[mysqld] ########basic settings######## server- id = 210
port = 3306 user = mysql bind_address = 0.0.0.0 character_set_server=utf8mb4 skip_name_resolve = 1 datadir = /data/mysql_data
log_error = error.log # slave上开启只读,避免应用误写导致主从数据不一致 read_only = on #######replication settings######## master_info_repository = TABLE relay_log_info_repository = TABLE log_bin = bin.log sync_binlog = 1 log_slave_updates binlog_format = row relay_log = relay.log relay_log_recovery = 1 binlog_gtid_simple_recovery = 1 slave_skip_errors = ddl_exist_errors ######semi sync replication settings######## plugin_dir= /usr/local/mysql/lib/plugin
plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
loose_rpl_semi_sync_master_enabled = 1 loose_rpl_semi_sync_slave_enabled = 1 loose_rpl_semi_sync_master_timeout = 5000 |
3. 搭建基于半同步主从
* Master 创建复制所使用的用户 [ 此处ip设置为slave服务IP或者% ]
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grant replication slave on *.* to 'rpl' @ '172.18.4.1' identified by '123' ;
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* master服务器上查看binlog文件名和日志位置
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mysql> show master status; + ------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | + ------------+----------+--------------+------------------+-------------------+
| bin.000003 | 1187 | | | | + ------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
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* slave服务器上设置master信息
未开启slave服务时,Slave_IO_Running与Slave_SQL_Running状态成No
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mysql> show slave status; # 未开启复制功能时,slave状态是空的 Empty set (0.00 sec)
mysql> change master to master_host= '172.18.0.1' ,master_user= 'rpl' ,master_password= '123' ,master_log_file= 'bin.000003' ,master_log_pos=1187;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State:
Master_Host: 172.18.0.1
Master_User: rpl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: bin.000003
Read_Master_Log_Pos: 1187
Relay_Log_File: relay.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: bin.000003
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: 1187
Relay_Log_Space: 120
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
Master_UUID:
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State:
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
1 row in set (0.00 sec)
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* 开启slave服务,并查看状态
正常开启slave服务后,Slave_IO_Running与Slave_SQL_Running状态成Yes
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mysql> start slave; Query OK, 0 rows affected (0.01 sec)
mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event
Master_Host: 172.18.0.1
Master_User: rpl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: bin.000003
Read_Master_Log_Pos: 1187
Relay_Log_File: relay.000002
Relay_Log_Pos: 277
Relay_Master_Log_File: 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: 1187
Relay_Log_Space: 440
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: 110
Master_UUID: 08ea3ca7-6dd4-11e7-a45c-00163e0432c5
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:
Executed_Gtid_Set:
Auto_Position: 0
1 row in set (0.00 sec)
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* Master上查看Slave连接信息
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mysql> show slave hosts; + -----------+------+------+-----------+--------------------------------------+
| Server_id | Host | Port | Master_id | Slave_UUID | + -----------+------+------+-----------+--------------------------------------+
| 210 | | 3306 | 110 | d6ceba69-6dd4-11e7-a462-00163e028c02 | + -----------+------+------+-----------+--------------------------------------+
1 row in set (0.00 sec)
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* Master上操作创建数据库与表,并插入数据
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mysql> create database mytest character set utf8mb4;
Query OK, 1 row affected (0.01 sec) mysql> use mytest; mysql> create table users(
-> id BIGINT NOT NULL AUTO_INCREMENT,
-> name VARCHAR (255) NOT NULL ,
-> sex ENUM( 'M' , 'F' ) NOT NULL DEFAULT 'M' ,
-> age INT SIGNED NOT NULL DEFAULT '0' ,
-> PRIMARY KEY (id)
-> )ENGINE=INNODB DEFAULT CHARSET=utf8mb4;
Query OK, 0 rows affected (0.03 sec)
mysql> insert into users values ( null , 'tom' , 'M' , 24), ( null , 'jak' , 'F' , 32), ( null , 'sea' , 'M' , 35), ( null , 'lisea' , 'M' , 29);
Query OK, 4 rows affected (0.01 sec)
Records: 4 Duplicates: 0 Warnings: 0 mysql> select * from users;
+ ----+-------+-----+-----+
| id | name | sex | age |
+ ----+-------+-----+-----+
| 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | sea | M | 35 | | 4 | lisea | M | 29 | + ----+-------+-----+-----+
4 rows in set (0.00 sec)
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* Slave上查看
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mysql> show databases; + --------------------+
| Database |
+ --------------------+
| information_schema | | mysql | | mytest | | performance_schema | | test | + --------------------+
5 rows in set (0.00 sec)
mysql> use mytest; Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables; + ------------------+
| Tables_in_mytest | + ------------------+
| users | + ------------------+
1 row in set (0.00 sec)
mysql> select * from users;
+ ----+-------+-----+-----+
| id | name | sex | age |
+ ----+-------+-----+-----+
| 1 | tom | M | 24 | | 2 | jak | F | 32 | | 3 | sea | M | 35 | | 4 | lisea | M | 29 | + ----+-------+-----+-----+
4 rows in set (0.00 sec)
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4. Master/Slave传输过程
5. 总结
以需求驱动技术,技术本身没有优略之分,只有业务之分。
本文转自asd1123509133 51CTO博客,原文链接:http://blog.51cto.com/lisea/1949707,如需转载请自行联系原作者