在Mysql中，一個Master可以連接多個slave，這篇文章講的就是在現有的master-slaves基礎上通過拷貝slave的方式往集羣中添加slave；
新添加的slave其實是掛在老的slave上的，這樣減少了多臺slave與master上的數據同步負載
One MySQL server can be the replication master to lots of slaves.
Having lots of slaves can be useful for scaling up your ability to handle lots of read traffic. The master replicates the same data out to all of the slaves, and you can load balance read traffic across all the slaves.
Note that this kind of replication doesn't help at all with scaling up your write capacity: the slaves shouldn't accept changes, because those changes won't propagate back to the master or to the other slaves. (Remember, replication is one-way.)
To Establish Replication we built our first slave using a backup from an existing master. That's not always practical, especially if the master is under heavy load.
In this procedure, we'll create a second slave using an existing slave. This is typical in very large deployments, especially if the slaves are all reached through a load balancer that can gracefully handle one slave being temporarily taken out of service.
Start:
1.先檢測現有的slave和Master的通信是否正常
master ~ $ mysql -u root
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.5.29-log MySQL Community Server (GPL)
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> INSERT INTO important.stuff SET details = "Replicating from master to old_slave";
Query OK, 1 row affected (0.03 sec)
mysql>old_slave ~ $ mysql -u root
mysql> select * from important.stuff;
+----+--------------------------------------+---------------------+
| id | details | happened |
+----+--------------------------------------+---------------------+
| 1 | Replicating from master to old_slave | 2013-04-15 22:19:07 |
+----+--------------------------------------+---------------------+
2 rows in set (0.00 sec)
mysql>2.暫停slave上的mysql：
old_slave ~ $ sudo service mysqld stop
Stopping mysqld: [ OK ]
old_slave ~ $3.對slave上的數據進行備份：
old_slave ~ $ sudo tar -czf /tmp/slave.tar.gz -C /var/lib/mysql/ .
old_slave ~ $ 4.重啓服務：
old_slave ~ $ sudo service mysqld start
Starting mysqld: [ OK ]
old_slave ~ $
new_slave ~ $ sudoedit /etc/my.cnf[mysqld]
server_id = 30
log_bin = mysql-bin
log_slave_updates = 1
relay_log = mysql-relay-bin
read_only = 1
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock6.重啓mysql服務使配置生效
new_slave ~ $ sudo service mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
new_slave ~ $ 7.停止服務：
new_slave ~ $ sudo service mysqld stop
Stopping mysqld: [ OK ]
new_slave ~ $
new_slave ~ $ sudo tar -zxf /tmp/slave.tar.gz -C /var/lib/mysql/
new_slave ~ $ sudo service mysqld start
Starting mysqld: [ OK ]
new_slave ~ $ 9.檢查備份狀態：
new_slave ~ $ mysql -u root
mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: master.example.com
Master_User: replicator
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 1306
Relay_Log_File: mysql-relay-bin.000004
Relay_Log_Pos: 253
Relay_Master_Log_File: mysql-bin.000001
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: 1306
Relay_Log_Space: 409
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: 10
1 row in set (0.00 sec)
mysql>
master ~ $ mysql -u root
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.5.29-log MySQL Community Server (GPL)
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> INSERT INTO important.stuff SET details = "Replicating from master to both slaves";
Query OK, 1 row affected (0.03 sec)
mysql>mysql> SELECT * FROM important.stuff ORDER BY id DESC LIMIT 1;
+----+----------------------------------------+---------------------+
| id | details | happened |
+----+----------------------------------------+---------------------+
| 5 | Replicating from master to both slaves | 2013-04-15 22:34:39 |
+----+----------------------------------------+---------------------+
1 row in set (0.00 sec)
mysql>