mysql半同步复制<二>

在MySQL5.6发布之后添加GTID、多线程等新特性之后,回顾一下从MySQL5.5引入的半同步复制.半同步的原理主要是:数据库执行更改前,确认更改操作至少被写入一台Slave的中继日志.半同步主要是保证数据完整性防止数据丢失.

实验环境MySQL5.6.16

主:
mysql> grant replication client,replication slave on *.* to repl@'192.168.23.%' identified by 'XXXXX';flush privilege;
配置文件添加:
binlog-do-db=percona
查看主的状态:
mysql> show master status\G
*************************** 1. row ***************************
             File: mysql-bin.000048
         Position: 120
     Binlog_Do_DB: percona
 Binlog_Ignore_DB: 
Executed_Gtid_Set: 
1 row in set (0.00 sec)
从:
从服务器需要启用中继日志,在配置文件中添加:
relay-log=relay-bin   
relay-log-index=relay-bin.index
replicate-do-db=percona
查看从的状态:
mysql> show variables like '%relay%';
+---------------------------+-----------------------------+
| Variable_name             | Value                       |
+---------------------------+-----------------------------+
| max_relay_log_size        | 0                           |
| relay_log                 | relay-bin                   |
| relay_log_basename        | /mysql/data/relay-bin       |
| relay_log_index           | /mysql/data/relay-bin.index |
| relay_log_info_file       | relay-log.info              |
| relay_log_info_repository | FILE                        |
| relay_log_purge           | ON                          |
| relay_log_recovery        | OFF                         |
| relay_log_space_limit     | 0                           |
| sync_relay_log            | 10000                       |
| sync_relay_log_info       | 10000                       |
+---------------------------+-----------------------------+
11 rows in set (0.00 sec)

mysql> change master to master_host='M_IP',master_user='repl',master_password='XXXXX';
启用主从的半同步

主:
mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';
Query OK, 0 rows affected (0.23 sec)

mysql> set global rpl_semi_sync_master_enabled=on ;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'rpl_%';
+------------------------------------+----------+
| Variable_name                      | Value    |
+------------------------------------+----------+
| rpl_semi_sync_master_enabled       | ON       |
| rpl_semi_sync_master_timeout       | 10000    |
| rpl_semi_sync_master_trace_level   | 32       |
| rpl_semi_sync_master_wait_no_slave | ON       |
| rpl_stop_slave_timeout             | 31536000 |
+------------------------------------+----------+
5 rows in set (0.00 sec)
从:
mysql> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';
Query OK, 0 rows affected (0.23 sec)

mysql> set global rpl_semi_sync_slave_enabled=on ;
Query OK, 0 rows affected (0.01 sec)

mysql> show variables like 'rpl_semi%';
+---------------------------------+-------+
| Variable_name                   | Value |
+---------------------------------+-------+
| rpl_semi_sync_slave_enabled     | ON    |
| rpl_semi_sync_slave_trace_level | 32    |
+---------------------------------+-------+
2 rows in set (0.00 sec)
监控半同步
mysql> show status like 'rpl_semi%';
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 1     |
| Rpl_semi_sync_master_net_avg_wait_time     | 0     |
| Rpl_semi_sync_master_net_wait_time         | 0     |
| Rpl_semi_sync_master_net_waits             | 0     |
| Rpl_semi_sync_master_no_times              | 0     |
| Rpl_semi_sync_master_no_tx                 | 0     |
| Rpl_semi_sync_master_status                | ON    |
| Rpl_semi_sync_master_timefunc_failures     | 0     |
| Rpl_semi_sync_master_tx_avg_wait_time      | 0     |
| Rpl_semi_sync_master_tx_wait_time          | 0     |
| Rpl_semi_sync_master_tx_waits              | 0     |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     |
| Rpl_semi_sync_master_wait_sessions         | 0     |
| Rpl_semi_sync_master_yes_tx                | 0     |
+--------------------------------------------+-------+
14 rows in set (0.01 sec)

参数Rpl_semi_sync_master_clients代表半同步连接的Slave数量
参数Rpl_semi_sync_master_status表示半同步的复制状态,正常状态应该是ON.如果显示OFF,有可能是人为关闭,还有就是因为某些原因恢复到异步复制状态,比如发生超时.

查看Slave同步状态
mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: M_IP
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 10
              Master_Log_File: mysql-bin.000048
          Read_Master_Log_Pos: 120
               Relay_Log_File: relay-bin.000003
                Relay_Log_Pos: 283
        Relay_Master_Log_File: mysql-bin.000048
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: percona
          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: 120
              Relay_Log_Space: 613
              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: 2
                  Master_UUID: 69a73914-62ca-11e3-870f-080027dff846
             Master_Info_File: /mysql/data/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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