《Mysql實例Mysql 主從數據庫同步(centos篇)》要點：
本文介紹了Mysql實例Mysql 主從數據庫同步(centos篇)，希望對您有用。如果有疑問，可以聯系我們。
環境:
主服務器:centos 5.2 mysql 5.1.35 源碼 IP:192.168.1.22
從服務器:centos 5.2 mysql 5.1.35 源碼? IP:192.168.1.33
配置:
一、主服務器
????1.1、創建一個復制用戶,具有replication slave 權限.
mysql>grant replication slave on *.* to 'repl'@'192.168.1.22' identified by 'repl';
??? 1.2、編輯my.cnf文件
vi /etc/my.cnf
添加
server-id=1
并開啟log-bin二進制日志文件
log-bin=mysql-bin
注:需要把默認的server-id=1去掉
??? 1.3、啟動mysql數據庫
mysqld_safe --user=mysql &
??? 1.4、設置讀鎖
mysql>flush tables with read lock;
??? 1.5、得到binlog日志文件名和偏移量
mysql>show master status;
+------------------+----------+--------------+------------------+
| File???????????? | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.0000010 |????? 106|????????????? |????????????????? |
+------------------+----------+--------------+------------------+
??? 1.6、備份要同步的數據庫
mysqldump test > test.sql
??? 1.7、解鎖
二、從服務器
??????? 2.1、編輯my.cnf文件
vi /etc/my.cnf
添加
server-id=2
注:需要把默認的server-id=1去掉
??? 2.2、啟動從數據庫
mysqld_safe --user=mysql &
??????? 2.3、對從數據庫進行相應設置
mysql> change master to
????????-> master_host='192.168.1.22'
????????-> master_user='repl'
????????-> master_password='repl'
????????-> master_log_file='mysql-bin.0000010'
????????-> master_log_pos=106;
??????? 2.4、啟動從服務器slave線程
執行show processlist命令顯示以下進程:
mysql>show processlist\G
*************************** 2. row ***************************
???????? Id: 2
???? User: system user
???? Host:????
???????? db: NULL
Command: Connect
???? Time: 2579
????State: Has read all relay log; waiting for the slave I/O thread to update it
???? Info: NULL
表示slave已經連接上master,開始接受并執行日志
???????? 2.5、查看slave線程狀態
mysql>show slave status;
*************************** 1. row ***************************
?????????????? Slave_IO_State: Waiting for master to send event
????????????????? Master_Host: 192.168.1.22
????????????????? Master_User: repl
????????????????? Master_Port: 3306
??????????????? Connect_Retry: 60
????????????? Master_Log_File: mysql-bin.0000010
????????? Read_Master_Log_Pos:?106
?????????????? Relay_Log_File: centos-relay-bin.000002
??????????????? Relay_Log_Pos: 529
??????? Relay_Master_Log_File: mysql-bin.0000010
???????????? 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:?106
????????????? Relay_Log_Space: 830
????????????? 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:
1 row in set (0.00 sec)
?
驗證是否配置正確
在從服務器上執行
show slave status\G;
Waiting for master to send event
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
如以上二行同時為Yes 說明配置成功
?
測試
1、在主服務器test數據庫中創建user表
mysql>use test;
mysql>create table user(id int);
2、在從服務器中查看user表
mysql>use test;
mysql> show tables like 'user';
+----------------------+
| Tables_in_test(user)?|
+----------------------+
| user?????????????? ? |????
+----------------------+
1 row in set (0.00 sec)
說明主從數據同步成功.
?
問題?
1.在從數據庫中查看slave狀態時出現
The slave I/O thread stops because master and slave have equal MySQL server ids; these ids must be different for replication to work (or the --replicate-same-server-id option must be used on slave but this does not always make sense; please check the manual before using it)
說明方從服務器里my.cnf中的server-id有相同的.
解決辦法:
修改my.cnf里的server-id,并重啟數據庫服務.my.cnf文件默認有server-id=1
?
其它說明
主服務器my.cnf
#binlog-do-db=需要備份的數據庫名,可寫多行
#binlog-ignore-db=不需要備份的數據庫名,可寫多行
從服務器my.cnf
# replicate-do-db=test??需要備份的數據庫名
# replicate-ignore-db=mysql 忽略的數據庫
# master-connect-retry=60 如果從服務器發現主服務器斷掉,重新連接的時間差(秒)
以下設置也可直接修改my.cnf配置文件
log-bin=mysql-bin
master-host=192.168.1.22
master-user=repl
master-password=repl
master-port=3306
主從服務器同步維護
由于各種原因,導致主從數據不一致,在負載低的時候,進行手動同步.
在主服務器上執行
?
mysql>flush tables with read lock;
Query OK,rows affected (0.01 sec)
mysql>show master status;
+------------------+----------+--------------+------------------+
| File???????????? | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.0000011 |????? 260|????????????? |????????????????? |
+------------------+----------+--------------+------------------+
在從服務器上執行
先得到當前主服務器的二進制文件名和偏移量,執行命令使從服務器與主服務器同步
mysql>select master_pos_wait('mysql-bin.0000011','260');
+--------------------------------------------------+
| master_pos_wait('mysql-bin.0000011','260')????????????|
+--------------------------------------------------+
|??0???????????????????????????????????????????????????????????????????|???
+--------------------------------------------------+
1 row in set (0.01 sec)
同步完成后,在主服務器上執行解鎖
?
切換主從服務器
?
當主服務器出現故障時,可將從服務器當主服務器來使用.步驟如下:
1、保證所有從數據庫都已經執行了relay log中的全部更新,在從服務器中執行
stop slave io_thread,用show processlist檢查,查看狀態是否是Has read all relay log,表示更新完成.
mysql>stop slave io_thread;
Query OK,0 affected (0.00 sec)
mysql>show processlist\G;
*************************** 2. row ***************************
???? Id: 2
?? User: system user
?? Host:
???? db: NULL
Command: Connect
?? Time: 4757
? State: Has read all relay log; waiting for the slave I/O thread to update it
?? Info: NULL
2、在從服務器上執行stop slave,reset master命令,重置成主數據庫
mysql>stop slave;
Query OK,0 affected (0.00 sec)
mysql>reset master;
Query OK,0 affected (0.00 sec)
3、刪除新的主服務器數據庫目錄中的master.info和relay-log.info文件,否則下次重啟時還會按照從服務器來啟動. MYSQL實例
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