mysql雙機熱備（主從，主主備份）以及基於gtid主備的配置

雙機熱備：保持兩個數據庫的狀態自動同步。對任何一個數據庫的操作都自動同步到另外一個數據庫，始終保持兩個數據庫數據一致。

說到mysql的備份，那就必須要瞭解（不是理解）mysql的備份原理，借用一整很多大神都用的圖：

這個備份的過程分爲兩部分：
主（Master）：打開復制模式之後，主服務器Master，會把自己的每一次改動都記錄到二進制日誌 Binarylog 中。
從（Slave）：打開復制模式之後，從服務器Slave的I/O線程，會用master上的賬號登陸到 master上，讀取master的Binarylog, 寫入到自己的中繼日誌 Relaylog，然後自己的sql線程會負責讀取這個中繼日誌，並執行一遍。如是，主服務器上的更改就同步到從服務器上了。

實驗需求：
本次實驗用的是mysql5.7.20版本：

[root@ansible ~]# mysql -V
mysql  Ver 14.14 Distrib 5.7.20, for Linux (x86_64) using  EditLine wrapper

mysql5.7.20的安裝如果還有問題，可以借鑑：
http://blog.csdn.net/weixin_37998647/article/details/78649092

實驗兩臺主機的IP分別是：
192.168.1.121 我們稱之爲A，
192.168.1.185 我們稱之爲B，
方便起見，直接關掉防火牆，selinux

廢話已經太多了，下面直接開幹吧：
1、在A上給用於備份的用戶授權（我們直接用root用戶）：

mysql> grant replication slave on *.* to 'root'@'192.168.1.185' identified by 'abc123';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_length=6;
Query OK, 0 rows affected (0.00 sec)
mysql> grant replication slave on *.* to 'root'@'192.168.1.185' identified by 'abc123';
Query OK, 0 rows affected, 1 warning (0.01 sec)

（報錯是因爲密碼太簡單，該本版的mysql帶有密碼強壯度校驗的模塊，按照上面的方法設置一下就可以了。）
2. 開啓主服務器的 binarylog。

[root@ansible ~]# vim /etc/my.cnf

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

log-bin = mysql-bin
binlog_format = mixed
server-id = 1

read-only = 0
binlog-ignore-db = information_schema
binlog-ignore-db = mysql
binlog-ignore-db = performance_schema
binlog-ignore-db = sys
binlog-ignore-db = zabbix
auto-increment-increment = 10
auto-increment-offset = 1

在最後面加了一些參數：
log-bin = mysql-bin
binlog_format = mixed
server-id = 1
read-only = 0
binlog-ignore-db = information_schema
binlog-ignore-db = mysql
binlog-ignore-db = performance_schema
binlog-ignore-db = sys
binlog-ignore-db = zabbix
auto-increment-increment = 10
auto-increment-offset = 1
解釋一下這些參數的的意義：
server-id 必須保證每個服務器不一樣。這可能和循環同步有關。防止進入死循環。

binlog-do-db 用來表示，只把哪些數據庫的改動記錄到binary日誌中。可以寫上關注hello數據庫。也可以把它註釋掉了。只是展示一下。可以寫多行，表示關注多個數據庫。

binlog-ignore-db 表示，需要忽略哪些數據庫。我這裏忽略了其他的5個數據庫。

後面兩個用於在雙主（多主循環）互相備份。因爲每臺數據庫服務器都可能在同一個表中插入數據，如果表有一個自動增長的主鍵，那麼就會在多服務器上出現主鍵衝突。解決這個問題的辦法就是讓每個數據庫的自增主鍵不連續。我假設需要將來可能需要10臺服務器做備份，所以auto-increment-increment 設爲10. 而 auto-increment-offset=1 表示這臺服務器的序號。從1開始，不超過auto-increment-increment。
這樣做之後，我在這臺服務器上插入的第一個id就是 1，第二行的id就是 11了，而不是2，（同理，在第二臺服務器上插入的第一個id就是2，第二行就是12，這個後面再介紹）這樣就不會出現主鍵衝突了。

保存，重啓mysql。

獲取主服務器狀態，和同步初態。

[root@ansible ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 775
Server version: 5.7.20-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, 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> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hello              |
| mysql              |
| performance_schema |
| sys                |
| zabbix             |
+--------------------+
8 rows in set (0.00 sec)

如果是剛安裝的就沒有“hello”和zabbix“”這兩個庫，上面我們已經設置了備份不管zabbix庫，這裏只關注hello庫就好了。

先鎖定 hello數據庫：

mysql> flush tables with read lock;
Query OK, 0 rows affected (0.15 sec)

導出數據，我們這裏只用導出hello數據庫，（如果你有多個數據庫作爲初態的話，需要導出所有這些數據庫：）

[root@ansible ~]# mysqldump --master-data -uroot -p hello > hello.sql
Enter password:
[root@ansible ~]# ll
-rw-r--r-- 1 root root  2632 Jan 22 13:36 hello.sql

然後查看A服務器的binary日誌位置：

記住這個文件名和位置，等會在從服務器上會用到。

mysql> show master status\G;
*************************** 1. row ***************************
             File: mysql-bin.000001
         Position: 1277
     Binlog_Do_DB:
 Binlog_Ignore_DB: information_schema,mysql,performance_schema,sys,zabbix
Executed_Gtid_Set:
1 row in set (0.00 sec)

ERROR:
No query specified

Master上的操作已經OK了，可以解除鎖定了：

mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)

把導出的hello.sql傳到185上去。

[root@ansible ~]# scp hello.sql 192.168.1.185:
hello.sql                                  100% 2632     2.6KB/s   00:00

設置從服務器 B 需要複製的數據庫

打開從服務器 B 的 /etc/my.cnf 文件：

[root@localhost ~]# vim /etc/my.cnf

在配置文件最後加上：
log-bin = mysql-bin
binlog_format = mixed
server-id = 2

replicate-ignore-db = information_schema
replicate-ignore-db = mysql
replicate-ignore-db = performance_schema
replicate-ignore-db = sys
replicate-ignore-db = zabbix
relay_log = mysqld-relay-bin
log-slave-updates = ON

解釋一下參數：
server-id 必須保證每個服務器不一樣。這可能和循環同步有關。防止進入死循環。

replicate-ignore-db 複製時需要排除的數據庫，我使用了，這個。除開系統的幾個數據庫和zabbix之外，所有的數據庫都複製。

relay_log 中繼日誌的名字。前面說到了，複製線程需要先把遠程的變化拷貝到這個中繼日誌中，在執行。

log-slave-updates 意思是，中繼日誌執行之後，這些變化是否需要計入自己的binarylog。當你的B服務器需要作爲另外一個服務器的主服務器的時候需要打開。就是雙主互相備份，或者多主循環備份。我們這裏需要，所以打開。
保存，重啓mysql。

從上導入初態。
把剛纔從A服務器上導出的 hello.sql 導入到 B的hello數據庫中，如果B現在沒有hello數據庫，請先創建一個，然後再導入：
創建數據庫：

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hello              |
| mysql              |
| performance_schema |
| sys                |
| zabbix             |
+--------------------+
6 rows in set (0.00 sec)

mysql> drop database hello;
Query OK, 0 rows affected (0.01 sec)

mysql> create database hello default charset utf8;
Query OK, 1 row affected (0.00 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hello              |
| mysql              |
| performance_schema |
| sys                |
| zabbix             |
+--------------------+
6 rows in set (0.00 sec)

把hello.sql 上傳到B上，然後導入：

[root@localhost ~]# mysql -uroot -p hello < hello.sql
Enter password:

開啓同步, 在B服務器上執行：

mysql> change master to master_host='192.168.1.121',master_user='root',master_password='abc123',master_log_file='mysql-bin.000001',master_log_pos=1277;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

重啓mysql，查看slave狀態：

[root@localhost ~]# /etc/init.d/mysqld restart
Stopping mysqld:                                           [  OK  ]
Starting mysqld:                                           [  OK  ]
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 12
Server version: 5.7.20-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, 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> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.121
                  Master_User: root
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 1277
               Relay_Log_File: mysqld-relay-bin.000003
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql-bin.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB: information_schema,mysql,performance_schema,sys,zabbix
           Replicate_Do_Table:
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                   Last_Errno: 0
                   Last_Error:
                   ……

至此，主從複製已經配置好了。現在測試一下：
在A上：

mysql> create database test;
Query OK, 1 row affected (0.03 sec)

B上show databases;

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hello              |
| mysql              |
| performance_schema |
| sys                |
| test               |
| zabbix             |
+--------------------+

說明主從複製已經成功了

如果只要求主從複製，那麼到這裏已經完成了，後面的內容可以不需再看

此時暫且不要在B上操作。
上面的結果已經看到A上的操作可以自動同步到B上，但是B上的操作還不能同步到A上。
如果要做B複製到A，跟上面的操作基本一樣，那下面的操作就不解釋了。
主主複製，即互爲主備，雙機熱備：
1. 在B中創建用戶；

mysql> grant replication slave on *.* to 'root'@'192.168.1.121' identified by 'abc123';
Query OK, 0 rows affected, 1 warning (0.01 sec)

打開 /etc/my.cnf ，開啓B的binarylog：

[root@localhost ~]# vim /etc/my.cnf
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

log-bin = mysql-bin
binlog_format = mixed
server-id = 2

replicate-ignore-db = information_schema
replicate-ignore-db = mysql
replicate-ignore-db = performance_schema
replicate-ignore-db = sys
replicate-ignore-db = zabbix
relay_log = mysqld-relay-bin
log-slave-updates = ON


read-only = 0
binlog-ignore-db = information_schema
binlog-ignore-db = mysql
binlog-ignore-db = performance_schema
binlog-ignore-db = sys
binlog-ignore-db = zabbix
auto-increment-increment = 10
auto-increment-offset = 2

此時不需要導出B的初態了，因爲它剛剛纔從A導過來。直接記住它的master日誌狀態：

mysql> show master status\G;
*************************** 1. row ***************************
             File: mysql-bin.000003
         Position: 154
     Binlog_Do_DB:
 Binlog_Ignore_DB: information_schema,mysql,performance_schema,sys,zabbix
Executed_Gtid_Set:
1 row in set (0.00 sec)

ERROR:
No query specified

登錄到A 服務器。開啓中繼：

[root@ansible ~]# vim /etc/my.cnf
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

log-bin = mysql-bin
binlog_format = mixed
server-id = 1

read-only = 0
binlog-ignore-db = information_schema
binlog-ignore-db = mysql
binlog-ignore-db = performance_schema
binlog-ignore-db = sys
binlog-ignore-db = zabbix
auto-increment-increment = 10
auto-increment-offset = 1

replicate-ignore-db = information_schema
replicate-ignore-db = mysql
replicate-ignore-db = performance_schema
replicate-ignore-db = sys
replicate-ignore-db = zabbix
relay_log = mysqld-relay-bin
log-slave-updates = ON

啓動同步：

mysql> change master to master_host = '192.168.1.185',master_user='root',master_password='abc123',master_log_file='mysql-bin.000003',master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.09 sec)

然後重啓mysql服務。

然後查看，slave狀態是否正常：

如果出現：
Slave_IO_Running: No
Slave_SQL_Running: No
解決辦法：先停掉mysql服務。找到這三個文件，把他們刪掉。一定要先停掉mysql服務。不然還是不成功。你需要重啓一下機器了。或者手動kill mysqld。

[root@ansible ~]# cd /var/lib/mysql
[root@ansible mysql]# rm -fr relay-log.info ansible-relay-bin.000001 ansible-relay-bin.index

再登錄啓動同步，之後再重啓

mysql> change master to master_host = '192.168.1.185',master_user='root',master_password='abc123',master_log_file='mysql-bin.000003',master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.09 sec)

重啓之後再查看：

mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.185
                  Master_User: root
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 154
               Relay_Log_File: mysqld-relay-bin.000003
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql-bin.000003
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB: information_schema,mysql,performance_schema,sys,zabbix
           Replicate_Do_Table:
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
      ……

出現連個NO的原因是：是因爲我們在配置A的中繼文件時改了中繼文件名，但是mysql沒有同步。

至此主主同步已經開啓了。
驗證一下，方法在B上插入數據，在A上查看。

===============================================

下面介紹一下基於gtid模式的複製配置：

配置文件的最後加上gtid_mode=on ； enforce_gtid_consistency=on 這兩項。即
主的配置：

# cat /etc/my.cnf
log-bin=mysql-bin
binlog_format=mixed
server-id=1
auto-increment-increment = 2
auto-increment-offset = 1
gtid_mode=on
enforce_gtid_consistency=on

從的配置：

gtid_mode=on
enforce_gtid_consistency=on
log-bin = mysql-bin
binlog_format = mixed
server-id = 2

主給從授權：

grant replication slave on *.* to 'root'@192.168.1.121 identified by 'abc123';

從找主：

change master to master_host='192.168.1.185',master_user='ha',master_password='Lockey+123',master_auto_position=1;

線上業務量比較大的時候，往往主庫會不停的寫入，此時就需要用到gtid 模式。他的好處就是，出庫不用鎖庫，而且自動找到position 的位置，不用擔心position不停變化而無法同步。

mysql雙機熱備（主從，主主備份）以及基於gtid主備的配置

mysql雙機熱備（主從，主主備份）以及基於gtid主備的配置

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