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MySQL Replication

How to Set Up Replication

目的: 我們假定A中心有一台Server Master1 ,而B中心有一台Server Master2. 為了方便我們在更新 Master1 的資料庫時, B中心的 Master2 資料庫也會自動更新 Master1所更新的部份. 反之亦然,使得各中心的資料庫內容得以同步.

實驗環境: Debian GNU/Linux Etch 4.0r4 with kernel 2.6.18 with MySQL 5.0

Part1: 安裝MySQL 5.0

步驟一 : 安裝 MySQL (假定 Master1 & Master2 都還沒有安裝 MySQL database)

使用指令
rider@ocean:~$ sudo apt-get install mysql-server-5.0 mysql-client-5.0

步驟二 : 為了要確保同步設定有效,我們讓MySQL可以在該網路介面上(interface)任意開啟監聽的埠(port)並藉由編輯 /etc/mysql/my.cnf 將 bind-address註釋起來

使用指令
rider@ocean1:~$ sudo vim /etc/mysql/my.cnf

# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
# bind-address            = 127.0.0.1

步驟三 : 重新啟動 MySQL

使用指令
rider@ocean1:~$ sudo su
root@ocean1:~$ /etc/init.d/mysql restart

步驟四 : 檢查MySQL所開啟的連接埠

使用指令
root@ocean1:~$ netstat -tap | grep mysql

tcp        0      0 *:mysql                 *:*                     LISTEN      21678/mysqld

步驟五 : 設定 root@localhost 的MySQL使用者密碼

使用指令
root@ocean1:~$ mysqladmin -u root password yourrootsqlpassword

/* @Master1 */
步驟六 : 設定 root@…的MySQL使用者密碼

使用指令
root@ocean1:~$ mysqladmin -h master1.nchc.org.tw -u root password yourrootsqlpassword

步驟七 : 設定一組同步使用者 slave2_user 給 Master2 能存取 Master1 的MySQL 資料庫的權限

使用指令
root@ocean1:~$ mysql -u root -p
-> 登入MySQL

Enter password: rootmysqlpasswd
-> 輸入root 的 MySQL 登入密碼

mysql>
GRANT REPLICATION SLAVE ON *.* TO 'slave2_user'@'%' IDENTIFIED BY 'slave2_password';
FLUSH PRIVILEGES;
quit;
-> 設定使用者: slave2_user 的同步權限並給予密碼

/* @Master2 */
步驟八 : 設定 root@…的MySQL使用者密碼,與設定一組同步使用者 slave1_user 給 Master1 能存取 Master2 的MySQL 資料庫的權限(重複步驟六&七: 設定 Master1 MySQL的方法)

使用指令

root@ocean2:~$ mysqladmin -h master1.nchc.org.tw -u root password yourrootsqlpassword

root@ocean2:~$ mysql -u root -p
-> 登入MySQL

Enter password: rootmysqlpasswd
-> 輸入root 的 MySQL 登入密碼

mysql>
GRANT REPLICATION SLAVE ON *.* TO 'slave1_user'@'%' IDENTIFIED BY 'slave1_password';
FLUSH PRIVILEGES;
quit;
-> 設定使用者: slave1_user 的同步權限並給予密碼

注意事項

我們假設我們已經在 Master1 建夠好一個 exampledb 並且存有資料表與相關資料內容. 接著我們要做的就是設定 exampledb 的副本到 Master2 , 接著也可將 Master2 的 exampledb 複製喔份回去Master1. 在設定資料庫複製 (MySQL Replication) 的同時我們先在 Master2 上建一個空的資料庫:exampledb.

/* @Master2 */
使用指令

root@ocean2:~$ mysql -u root -p
-> 登入MySQL

mysql>
CREATE DATABASE exampledb;
quit;

Part2: 設定資料庫複製(Replication)

首先我們要透過編輯 /etc/mysql/my.cnf 來完成 master-master replication 的設定, 而 master-master replication 最重要的兩個設定選項就是 auto_increment_increment & auto_increment_offset

auto_increment_increment: 控制連續性增量的AUTO_INCREMENT值.
auto_increment_offset: 決定AUTO_INCREMENT欄位的起始值.

假設我們有 N 個 MySQL nodes (本範例是兩個nodes,所以 N=2),因此 "auto_increment_increment" 在每各node的值都是 2 , 而每各node都必須給 "value for auto_increment_offset" 一各不同的值(1, 2, ..., N). 而接下來我們便要開始設定本範例中的兩各 MySQL nodes.

/* @Master1 */
步驟一 : 編輯 /etc/mysql/my.cnf -> 從[mysqld]開始新增以下的選項,並且將有衝突的相關選項給註釋掉

使用指令

root@ocean1:~$ vim /etc/mysql/my.cnf

[...]
[mysqld]
#
# * Basic Settings
#

#
# * IMPORTANT
#   If you make changes to these settings and your system uses apparmor, you may
#   also need to also adjust /etc/apparmor.d/usr.sbin.mysqld.
#
server-id = 1
replicate-same-server-id = 0
auto-increment-increment = 2
auto-increment-offset = 1

master-host = 192.168.0.101
master-user = slave1_user
master-password = slave1_password
master-connect-retry = 60
replicate-do-db = exampledb

log-bin = /var/log/mysql/mysql-bin.log
binlog-do-db = exampledb

relay-log = /var/lib/mysql/slave-relay.log
relay-log-index = /var/lib/mysql/slave-relay-log.index

expire_logs_days        = 10
max_binlog_size         = 500M
[...]

步驟二 : 重新啟動 MySQL 使用指令

root@ocean1:~$ /etc/init.d/mysql restart

/* @Master2 */
步驟三 : 對 Master2 重複相同的設定步驟(步驟一 ~ 步驟二)-> 編輯 /etc/mysql/my.cnf -> 從[mysqld]開始新增以下的選項,並且將有衝突的相關選項給註釋掉.再重新啟動MySQL

使用指令

root@ocean2:~$ vim /etc/mysql/my.cnf

[...]
[mysqld]
#
# * Basic Settings
#

#
# * IMPORTANT
#   If you make changes to these settings and your system uses apparmor, you may
#   also need to also adjust /etc/apparmor.d/usr.sbin.mysqld.
#
server-id = 2
replicate-same-server-id = 0
auto-increment-increment = 2
auto-increment-offset = 2

master-host = 192.168.0.100
master-user = slave2_user
master-password = slave2_password
master-connect-retry = 60
replicate-do-db = exampledb

log-bin= /var/log/mysql/mysql-bin.log
binlog-do-db = exampledb

relay-log = /var/lib/mysql/slave-relay.log
relay-log-index = /var/lib/mysql/slave-relay-log.index

expire_logs_days        = 10
max_binlog_size         = 500M
[...]

root@ocean2:~$ /etc/init.d/mysql restart

/* @Master1 */
步驟四 : 我們將鎖定在 Master1 上的 exampledb 資料庫, 且查詢 Master1 的主機狀態資訊而將 exampledb 給 dump(傾倒)出來 (因為我們待會要將傾倒出來的 exampledb 匯入到 Master2去,這樣兩各nodes的資料庫都將會有相同的資料), 最後將 exampledb 資料庫給解鎖(unlock)以便後續使用

使用指令

root@ocean1:~$ mysql -u root -p

mysql>
USE exampledb;
FLUSH TABLES WITH READ LOCK;
SHOW MASTER STATUS;

接著應該會顯示如下的資訊 (請將他記下來之後會有用)

mysql> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000009 |       98 | exampledb    |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

mysql>

說明:
這時暫時還請勿離開 MySQL命令列(MySQL shell). 這時如果下exit指令而離開的話資料庫鎖定(database lock)將會被移除,因為我們必須先做完 MySQL dump(資料庫傾倒). 由於我們還有一各MySQL shell在開啟狀態,所以我們得藉由開啟第二各指令對話窗(command line window)來做 MySQL dump 而產生snapshot.sql並且透過 SCP(Secure Copy) 來傳送至Master2.

/* @Master1 */
步驟五 : 在透過第二各指令對話窗(command line window)將資料庫給傾倒出來並SCP過去到遠端的 Master2的 /tmp資料夾暫存後便可關閉視窗二. 亦可離開並關閉第一視窗的 MySQL shell 藉以將資料庫解鎖

使用指令

root@ocean1:~$ cd /tmp

root@ocean1:~$ mysqldump -u root -pyourrootsqlpassword --opt exampledb > snapshot.sql

root@ocean1:~$ scp snapshot.sql root@192.168.0.101:/tmp (Master2 IP: 192.168.0.101)

步驟六 : 可以離開並關閉第一各指令對話窗(command line window)的 MySQL shell 藉以將資料庫解鎖

使用指令

mysql> UNLOCK TABLES;

mysql> quit;

/* @Master2 */
步驟七 : 我們可以匯入由 Master1 所 SQL dump 出來的 snapshot.sql 到 Master2 的 MySQL 資料庫

使用指令

root@ocean2:~$ /usr/bin/mysqladmin --user=root --password=yourrootsqlpassword stop-slave

root@ocean2:~$ cd /tmp

root@ocean2:~$ mysql -u root -pyourrootsqlpassword exampledb < snapshot.sql

/* @Master2 */
步驟八 : 接著我們去查詢 Master2 的主機狀態並將他紀錄下來待會會用到

使用指令

root@ocean2:~$ mysql -u root -p

mysql> USE exampledb;

mysql> FLUSH TABLES WITH READ LOCK;

mysql> SHOW MASTER STATUS;

mysql> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000009 |      783 | exampledb    |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

/* @Master2 */
步驟九 : 然後我們解除該狀態表格的鎖定,並且透過以下指令來使得 Master2 成為 Master1的從屬(slave)之一

使用指令

mysql> UNLOCK TABLES;

mysql> CHANGE MASTER TO MASTER_HOST='192.168.0.100', MASTER_USER='slave2_user', MASTER_PASSWORD='slave2_password', MASTER_LOG_FILE='mysql-bin.000009', MASTER_LOG_POS=98;

/* @Master2 */
步驟十 : 最後啟動該從屬(slave)關係

使用指令

mysql> START SLAVE;

/* @Master2 */
步驟十一 : 檢查該從屬(slave)狀態
說明: 請注意 Slave_IO_Running 與 Slave_SQL_Running 兩各值的輸出應該均為 "Yes",如果不是則一定有哪裡設定有誤. 請到 /var/log/syslog 尋找相關錯誤訊息並與以修正

使用指令

mysql> SHOW SLAVE STATUS;

mysql> SHOW SLAVE STATUS;
+----------------------------------+---------------+-------------+-------------+---------------+------------------+---------------------+--------------------+---------------+-----------------------+------------------+-------------------+-----------------+---------------------+--------------------+------------------------+-------------------------+-----------------------------+------------+------------+--------------+---------------------+-----------------+-----------------+----------------+---------------+--------------------+--------------------+--------------------+-----------------+-------------------+----------------+-----------------------+
| Slave_IO_State                   | Master_Host   | Master_User | Master_Port | Connect_Retry | Master_Log_File  | Read_Master_Log_Pos | Relay_Log_File     | Relay_Log_Pos | Relay_Master_Log_File | Slave_IO_Running | Slave_SQL_Running | Replicate_Do_DB | Replicate_Ignore_DB | Replicate_Do_Table | Replicate_Ignore_Table | Replicate_Wild_Do_Table | Replicate_Wild_Ignore_Table | Last_Errno | Last_Error | Skip_Counter | Exec_Master_Log_Pos | Relay_Log_Space | Until_Condition | Until_Log_File | Until_Log_Pos | Master_SSL_Allowed | Master_SSL_CA_File | Master_SSL_CA_Path | Master_SSL_Cert | Master_SSL_Cipher | Master_SSL_Key | Seconds_Behind_Master |
+----------------------------------+---------------+-------------+-------------+---------------+------------------+---------------------+--------------------+---------------+-----------------------+------------------+-------------------+-----------------+---------------------+--------------------+------------------------+-------------------------+-----------------------------+------------+------------+--------------+---------------------+-----------------+-----------------+----------------+---------------+--------------------+--------------------+--------------------+-----------------+-------------------+----------------+-----------------------+
| Waiting for master to send event | 192.168.0.100 | slave2_user |        3306 |            60 | mysql-bin.000009 |                  98 | slave-relay.000002 |           235 | mysql-bin.000009      | Yes              | Yes               | exampledb       |                     |                    |                        |                         |                             |          0 |            |            0 |                  98 |             235 | None            |                |             0 | No                 |                    |                    |                 |                   |                |                     0 |
+----------------------------------+---------------+-------------+-------------+---------------+------------------+---------------------+--------------------+---------------+-----------------------+------------------+-------------------+-----------------+---------------------+--------------------+------------------------+-------------------------+-----------------------------+------------+------------+--------------+---------------------+-----------------+-----------------+----------------+---------------+--------------------+--------------------+--------------------+-----------------+-------------------+----------------+-----------------------+
1 row in set (0.00 sec)

mysql>

/* @Master2 */
步驟十二 : 最後你可以離開 Master2 的 MySQL shell了. 而此時 Master1 複製到 Master2 的 MySQL replication 也已經設定完成

使用指令

mysql> quit

/* @Master1 */
步驟十三 : 在 Master1 複製到 Master2 的 MySQL replication 設定完成後,接著便是要設定 Master2 複製到 Master1 的 MySQL replication. 而在這之前我們得先停止在 Master1上的從屬關係,並且反過來讓 Master1 成為 Master2 的從屬.

使用指令

root@ocean1:~$ mysql -u root -p

mysql> STOP SLAVE;

/* @Master1 */
步驟十四 : 請確認你目前在在使用 SHOW MASTER STATUS 的值,並且在 Master2 上執行如下的指令

使用指令

mysql> CHANGE MASTER TO MASTER_HOST='192.168.0.101', MASTER_USER='slave1_user', MASTER_PASSWORD='slave1_password', MASTER_LOG_FILE='mysql-bin.000009', MASTER_LOG_POS=783; (Master2 IP: 192.168.0.101)

/* @Master1 */
步驟十五 : 接著便可以啟動 Master1 上的從屬關係

使用指令

mysql> START SLAVE;

/* @Master1 */
步驟十六 : 最後便要檢查該從屬狀態
說明: 請注意 Slave_IO_Running 與 Slave_SQL_Running 兩各值的輸出應該均為 "Yes",如果不是則一定有哪裡設定有誤. 請到 /var/log/syslog 尋找相關錯誤訊息並與以修正

使用指令

mysql> SHOW SLAVE STATUS;

mysql> SHOW SLAVE STATUS;
+----------------------------------+---------------+-------------+-------------+---------------+------------------+---------------------+--------------------+---------------+-----------------------+------------------+-------------------+-----------------+---------------------+--------------------+------------------------+-------------------------+-----------------------------+------------+------------+--------------+---------------------+-----------------+-----------------+----------------+---------------+--------------------+--------------------+--------------------+-----------------+-------------------+----------------+-----------------------+
| Slave_IO_State                   | Master_Host   | Master_User | Master_Port | Connect_Retry | Master_Log_File  | Read_Master_Log_Pos | Relay_Log_File     | Relay_Log_Pos | Relay_Master_Log_File | Slave_IO_Running | Slave_SQL_Running | Replicate_Do_DB | Replicate_Ignore_DB | Replicate_Do_Table | Replicate_Ignore_Table | Replicate_Wild_Do_Table | Replicate_Wild_Ignore_Table | Last_Errno | Last_Error | Skip_Counter | Exec_Master_Log_Pos | Relay_Log_Space | Until_Condition | Until_Log_File | Until_Log_Pos | Master_SSL_Allowed | Master_SSL_CA_File | Master_SSL_CA_Path | Master_SSL_Cert | Master_SSL_Cipher | Master_SSL_Key | Seconds_Behind_Master |
+----------------------------------+---------------+-------------+-------------+---------------+------------------+---------------------+--------------------+---------------+-----------------------+------------------+-------------------+-----------------+---------------------+--------------------+------------------------+-------------------------+-----------------------------+------------+------------+--------------+---------------------+-----------------+-----------------+----------------+---------------+--------------------+--------------------+--------------------+-----------------+-------------------+----------------+-----------------------+
| Waiting for master to send event | 192.168.0.101 | slave1_user |        3306 |            60 | mysql-bin.000009 |                 783 | slave-relay.000002 |           235 | mysql-bin.000009      | Yes              | Yes               | exampledb       |                     |                    |                        |                         |                             |          0 |            |            0 |                 783 |             235 | None            |                |             0 | No                 |                    |                    |                 |                   |                |                     0 |
+----------------------------------+---------------+-------------+-------------+---------------+------------------+---------------------+--------------------+---------------+-----------------------+------------------+-------------------+-----------------+---------------------+--------------------+------------------------+-------------------------+-----------------------------+------------+------------+--------------+---------------------+-----------------+-----------------+----------------+---------------+--------------------+--------------------+--------------------+-----------------+-------------------+----------------+-----------------------+
1 row in set (0.00 sec)

mysql>

/* @Master1 */
步驟十七 : 最後便可以離開 MySQL shell

使用指令

mysql> quit

進行到此若沒有任何錯誤發生,則 MySQL master-master replication 已經可以正常運作了. 如果有不知名錯誤發生,請先到 /var/log/syslog 尋找與 Master1 or Master2 MySQL 相關的錯誤.

Reference:

(1) MySQL Replication http://dev.mysql.com/doc/refman/5.0/en/replication.html

(2) Setting Up Master-Master Replication With MySQL 5 On Debian Etch http://www.howtoforge.com/mysql5_master_master_replication_debian_etch

(3) MySQL Master Master Replication http://www.howtoforge.com/mysql_master_master_replication

(4) Script To Check If MySQL Master Master Replication Is Working Correctly http://www.howtoforge.com/script-to-check-if-mysql-master-master-replication-is-working-correctly

備註: 以上安裝與設定內容大部份係參照reference(2)的操作程序並予以中文化以利後續文件撰寫之用.

Last modified 16 years ago Last modified on Oct 8, 2008, 1:51:42 PM

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