mysql主從複製及維護--單主、雙主

時間 2019-11-11

標籤 mysql 主從複製維護欄目 MySQL 简体版

原文原文鏈接

本文講述了MySQL單主、雙主模式的配置方法、注意事項、和維護的一些事項。node

1. 單主配置實例

1.1 總體流程：

master與slave時間同步
master開啓二進制記錄功能並受權一個特定的用戶對二進制文件有複製權限
slave開啓中繼日誌功能，執行同步語句，開啓同步功能。
- 注：版本號不一致時，master版本可比slave版本低

1.2 master端配置

編輯/etc/my.cnf，在mysqld配置段中添加如下內容（需重啓服務）mysql

server-id=1
log_bin=/data/mysql/logs/mysql-bin

啓動數據庫並作受權：sql

MariaDB [(none)]> GRANT REPLICATION SLAVE,REPLICATION CLIENT ON *.* TO 'node2'@'192.168.200.%' IDENTIFIED BY 'node2pass';
MariaDB [(none)]> FLUSH PRIVILEGES;

1.3 master端注意事項

/data/mysql/logs目錄需存在，且屬主、屬組爲運行mysql的用戶（因mysql需在該目錄建立、寫入文件）
mysql-bin可自行定義。
server-id後面的數值惟一，各節點之間不能重複。

1.4 slave端配置

編輯/etc/my.cnf，在mysqld配置段中添加如下內容（需重啓服務）數據庫

server-id=2
relay-log=/data/mysql/logs/relay-bin

啓動服務後設置主節點並啓動服務器

MariaDB [(none)]> change master to master_host='192.168.200.41',master_port=3306,master_user='node2',master_password='node2pass',master_log_file='mysql-bin.000003', master_log_pos =4;
MariaDB [(none)]> START SLAVE;
MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.200.41
                  Master_User: node2
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 927
               Relay_Log_File: relay-bin.000003
                Relay_Log_Pos: 604
        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: 927
              Relay_Log_Space: 1783
              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: 1

查看show slave status時，Slave_IO_Running和Slave_SQL_Running狀態爲yes時即成功。可在主節點建立庫或者表查看從節點是否也有。ide

1.5 slave端注意事項

/data/mysql/logs目錄需存在，且屬主、屬組爲運行mysql的用戶（因mysql需在該目錄建立、寫入文件）
relay-bin名字可自行定義。
server-id後面的數值惟一，不能重複。

change master時，若master_log_pos的位置不正確，可能會致使Slave I/O thread失敗。錯誤日誌以下：

180603 16:46:49 [Note] Slave I/O thread: connected to master 'node2@192.168.200.41:3306',replication started in log 'mysql-bin.000003' at position 760
180603 16:46:49 [ERROR] Error reading packet from server: binlog truncated in the middle of event; consider out of disk space on master; the first event 'mysql-bin.000003' at 760, the last event read from 'mysql-bin.000003' at 760, the last byte read from 'mysql-bin.000003' at 769. ( server_errno=1236)
180603 16:46:49 [ERROR] Slave I/O: Got fatal error 1236 from master when reading data from binary log: 'binlog truncated in the middle of event; consider out of disk space on master; the first event 'mysql-bin.000003' at 760, the last event read from 'mysql-bin.000003' at 760, the last byte read from 'mysql-bin.000003' at 769.', Error_code: 1236

解決方法：
經過show binary logs查看當前的二進制文件有哪些，再經過show binlog events in 'BINLOG FILE NAME'，找到正確的POS位置，並在change master時使用正確的POS位置。測試

MariaDB [(none)]> show binary logs;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |     30355 |
| mysql-bin.000002 |   1038814 |
| mysql-bin.000003 |       491 |
+------------------+-----------+
3 rows in set (0.00 sec)

MariaDB [(none)]> show binlog events in 'mysql-bin.000003';
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
| Log_name         | Pos | Event_type  | Server_id | End_log_pos | Info                                                                                             |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
| mysql-bin.000003 |   4 | Format_desc |         1 |         245 | Server ver: 5.5.56-MariaDB, Binlog ver: 4                                                        |
| mysql-bin.000003 | 245 | Query       |         1 |         416 | grant replication slave,replication client on *.* to lxk@'192.168.200.%' identified by 'lxkpass' |
| mysql-bin.000003 | 416 | Query       |         1 |         491 | flush privileges                                                                                 |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
3 rows in set (0.00 sec)

如上代碼：選擇Pos（開始位置）或者End_log_pos（結束位置）均可以。spa

2. 雙主配置實例

2.1 總體流程：

節點1與節點2時間同步
節點1與節點2開啓二進制日誌及中繼日誌功能並受權一個特定的用戶對二進制文件有複製權限
節點1與節點2執行同步語句，開啓同步功能。
注：
版本號不一致時，master版本可比slave版本低

2.2 配置文件：

節點1：編輯/etc/my.cnf，在mysqld配置段添加如下內容保存退出：命令行

log_bin=/data/mysql/logs/mysql-bin
relay_log=/data/mysql/logs/relay-log

注：要確保mysql對/data/mysql/logs目錄有讀寫權限
節點2：編輯/etc/my.cnf，在mysqld配置段添加如下內容保存退出：線程

log_bin=/data/mysql/logs/mysql-bin
relay_log=/data/mysql/logs/relay-log

注：要確保mysql對/data/mysql/logs目錄有讀寫權限

節點1 IP：192.168.200.41 節點2 IP：192.168.200.42

2.3 數據庫操做：

節點1與節點2都進行一樣的操做以受權一個用戶：

MariaDB [(none)]> grant replication slave,replication client on *.* to lxk@'192.168.200.%' identified by 'lxkpass';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

查看要複製的Pos位置：
節點1：

MariaDB [(none)]> show master status;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000003 |      491 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

MariaDB [(none)]> show binlog events in 'mysql-bin.000003';
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
| Log_name         | Pos | Event_type  | Server_id | End_log_pos | Info                                                                                             |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
| mysql-bin.000003 |   4 | Format_desc |         1 |         245 | Server ver: 5.5.56-MariaDB, Binlog ver: 4                                                        |
| mysql-bin.000003 | 245 | Query       |         1 |         416 | grant replication slave,replication client on *.* to lxk@'192.168.200.%' identified by 'lxkpass' |
| mysql-bin.000003 | 416 | Query       |         1 |         491 | flush privileges                                                                                 |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
3 rows in set (0.00 sec)

節點2：

MariaDB [(none)]> show master status;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000003 |      491 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

MariaDB [(none)]> show binlog events in 'mysql-bin.000003';
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
| Log_name         | Pos | Event_type  | Server_id | End_log_pos | Info                                                                                             |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
| mysql-bin.000003 |   4 | Format_desc |         2 |         245 | Server ver: 5.5.56-MariaDB, Binlog ver: 4                                                        |
| mysql-bin.000003 | 245 | Query       |         2 |         416 | grant replication slave,replication client on *.* to lxk@'192.168.200.%' identified by 'lxkpass' |
| mysql-bin.000003 | 416 | Query       |         2 |         491 | flush privileges                                                                                 |
+------------------+-----+-------------+-----------+-------------+--------------------------------------------------------------------------------------------------+
3 rows in set (0.00 sec)

由於爲新數據庫，兩個節點的pos值相同，都爲491，生產環境根據須要調整，通常位置的選取都是從受權後的位置開始。

執行同步語句：

節點1：

MariaDB [(none)]> change master to master_host='192.168.200.42',master_user='lxk',master_password='lxkpass',master_log_file='mysql-bin.000003',master_log_pos=491;
Query OK, 0 rows affected (0.27 sec)

MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)

節點2：

MariaDB [(none)]> change master to master_host='192.168.200.41',master_user='lxk',master_password='lxkpass',master_log_file='mysql-bin.000003',master_log_pos=491;
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)

2.4 查看狀態

MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.200.41       #主節點地址
                  Master_User: lxk                          #主節點用戶名
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 491
               Relay_Log_File: relay-bin.000002
                Relay_Log_Pos: 529
        Relay_Master_Log_File: mysql-bin.000003
             Slave_IO_Running: Yes                  #IO線程開啓
            Slave_SQL_Running: Yes              #SQL線程開啓

只要執行結果中slave_IO_Runing和Slave_SQL_Runing狀態爲Yes，即表示從節點鏈接主節點成功併成功開啓複製功能。

2.5 測試：

節點2建立一個數據庫名爲testdb

MariaDB [(none)]> create database testdb;
Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| test               |
| testdb             |
+--------------------+
5 rows in set (0.00 sec)

節點1查看本地數據庫

MariaDB [(none)]> show databases;                    
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| test               |
| testdb             |
+--------------------+
5 rows in set (0.00 sec)

3 監控和維護：

清理日誌
- 隨着服務的運行，日誌文件會愈來愈多，愈來愈大。二進制最好複製到其它節點（二進制文件必定要保存），再在mysql命令行下刪除。經過PURGE的操做會反應到.index文件中。

MariaDB [testdb]> show binary logs;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |     30355 |
| mysql-bin.000002 |   1038814 |
| mysql-bin.000003 |      1364 |
+------------------+-----------+
3 rows in set (0.00 sec)

MariaDB [testdb]> purge binary logs to 'mysql-bin.000003';          #清空至mysql-bin.000003的日誌
Query OK, 0 rows affected (0.01 sec)

MariaDB [testdb]> show binary logs;         #再次查看日誌
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000003 |      1364 |
+------------------+-----------+
1 row in set (0.00 sec)

[root@node1 ~]# ls /data/mysql/logs/            #查看二進制日誌保存目錄，000003以前的都已經刪除
mysql-bin.000003  mysql-bin.index  relay-log.000001  relay-log.000002  relay-log.index

複製監控
- 判斷從服務器是否落後於主服務器，經過show slave status\G查看。
- Seconds_Behind_Master: 0 #表示未落後
如何肯定主從節點數據是否一致
- 雙主模型中極易發生，可用procona-tools中的pt-table-checksum
主從數據不一致時的修復方法
- 停掉複製線程再從新啓動，從服務器就會啓動複製，達到與主節點一致。

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