Mysql 主从数据库同步(centos篇)
环境:
主服务器:centos 5.2 mysql 5.1.35 源码 IP:192.168.1.22
从服务器:centos 5.2 mysql 5.1.35 源码 IP:192.168.1.33
配置:
一、主服务器
1.1、创建一个复制用户，具有replication slave 权限。
mysql>grant replication slave on *.* to 'repl'@'192.168.1.22' identified by 'repl';
1.2、编辑my.cnf文件
vi /etc/my.cnf
添加
server-id=1
并开启log-bin二进制日志文件
log-bin=mysql-bin
添加
server-id=1
并开启log-bin二进制日志文件
log-bin=mysql-bin
注:需要把默认的server-id=1去掉
1.3、启动mysql数据库
mysqld_safe --user=mysql &
1.4、设置读锁
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| | |
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.0000010 | 106| | |
+------------------+----------+--------------+------------------+
1.6、备份要同步的数据库
mysqldump test > test.sql
1.7、解锁
mysql>unlock tables;
二、从服务器
2.1、编辑my.cnf文件
vi /etc/my.cnf
添加
server-id=2
添加
server-id=2
注:需要把默认的server-id=1去掉
2.2、启动从数据库
mysqld_safe --user=mysql &
2.3、对从数据库进行相应设置
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;
-> master_host='192.168.1.22'
-> master_user='repl'
-> master_password='repl'
-> master_log_file='mysql-bin.0000010'
-> master_log_pos=106;
2.4、启动从服务器slave线程
mysql>start slave;
执行show processlist命令显示以下进程:
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已经连接上master，开始接受并执行日志*************************** 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
2.5、查看slave线程状态
mysql>show slave status;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.22
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:
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)
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)
验证是否配置正确
在从服务器上执行
show slave status\G;
Waiting for master to send event
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Waiting for master to send event
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
如以上二行同时为Yes 说明配置成功
测试
1、在主服务器test数据库中创建user表
mysql>use test;
mysql>create table user(id int);
mysql>create table user(id int);
2、在从服务器中查看user表
mysql>use test;
mysql> show tables like 'user';
+----------------------+
| Tables_in_test(user) |
+----------------------+
| user |
+----------------------+
1 row in set (0.00 sec)
mysql> show tables like 'user';
+----------------------+
| Tables_in_test(user) |
+----------------------+
| user |
+----------------------+
1 row in set (0.00 sec)
说明主从数据同步成功。
问题?
1.在从数据库中查看slave状态时出现
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)
说明方从服务器里my.cnf中的server-id有相同的。
解决办法:
修改my.cnf里的server-id，并重启数据库服务。my.cnf文件默认有server-id=1
其它说明
主服务器my.cnf
#binlog-do-db=需要备份的数据库名，可写多行
#binlog-ignore-db=不需要备份的数据库名，可写多行
从服务器my.cnf
#binlog-ignore-db=不需要备份的数据库名，可写多行
从服务器my.cnf
# replicate-do-db=test 需要备份的数据库名
# replicate-ignore-db=mysql 忽略的数据库
# master-connect-retry=60 如果从服务器发现主服务器断掉，重新连接的时间差(秒)
# replicate-ignore-db=mysql 忽略的数据库
# master-connect-retry=60 如果从服务器发现主服务器断掉，重新连接的时间差(秒)
以下设置也可直接修改my.cnf配置文件
log-bin=mysql-bin
master-host=192.168.1.22
master-host=192.168.1.22
master-user=repl
master-password=repl
master-port=3306
master-port=3306
主从服务器同步维护
由于各种原因，导致主从数据不一致，在负载低的时候，进行手动同步.
在主服务器上执行
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| | |
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.0000011 | 260| | |
+------------------+----------+--------------+------------------+
在从服务器上执行
先得到当前主服务器的二进制文件名和偏移量,执行命令使从服务器与主服务器同步
mysql>select master_pos_wait('mysql-bin.0000011','260');
+--------------------------------------------------+
| master_pos_wait('mysql-bin.0000011','260') |
+--------------------------------------------------+
| 0 |
+--------------------------------------------------+
1 row in set (0.01 sec)
+--------------------------------------------------+
| master_pos_wait('mysql-bin.0000011','260') |
+--------------------------------------------------+
| 0 |
+--------------------------------------------------+
1 row in set (0.01 sec)
同步完成后，在主服务器上执行解锁
mysql>unlock tables;
切换主从服务器
当主服务器出现故障时，可将从服务器当主服务器来使用.步骤如下:
1、保证所有从数据库都已经执行了relay log中的全部更新，在从服务器中执行
stop slave io_thread,用show processlist检查，查看状态是否是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;
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
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、在从服务器上执行stop slave，reset master命令，重置成主数据库
mysql>stop slave;
Query OK,0 affected (0.00 sec)
mysql>reset master;
Query OK,0 affected (0.00 sec)
Query OK,0 affected (0.00 sec)
mysql>reset master;
Query OK,0 affected (0.00 sec)
3、删除新的主服务器数据库目录中的master.info和relay-log.info文件，否则下次重启时还会按照从服务器来启动.
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