MySQL 3M环境搭建

Bertha 。 2023-01-01 02:54 114阅读 0赞

# MySQL 3M环境搭建 #

## 环境准备 ##

<table> 
 <thead> 
  <tr> 
   <th>ip</th> 
   <th>port</th> 
   <th>type</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>192.168.38.101</td> 
   <td>3306</td> 
   <td>master</td> 
  </tr> 
  <tr> 
   <td>192.168.38.102</td> 
   <td>3306</td> 
   <td>master</td> 
  </tr> 
  <tr> 
   <td>192.168.38.103</td> 
   <td>3306</td> 
   <td>slave</td> 
  </tr> 
  <tr> 
   <td>192.168.38.88</td> 
   <td>3306</td> 
   <td>write-vip</td> 
  </tr> 
  <tr> 
   <td>192.168.38.66</td> 
   <td>3306</td> 
   <td>read-vip</td> 
  </tr> 
 </tbody> 
</table>

mysql版本5.7.24  
mysql安装详情可以参照：https://www.jianshu.com/p/276d59cbc529

### mysql-1（192.168.38.101）修改配置 ###

[root@mysql-1 ~]# vim /etc/my.cnf
    [mysqld]
    log_bin
    server-id=1

### mysql-2（192.168.38.102）修改配置 ###

[root@mysql-2 ~]# vim /etc/my.cnf
    [mysqld]
    log_bin
    server-id=2

### mysql-3（192.168.38.103）修改配置 ###

[root@mysql-3 ~]# vim /etc/my.cnf
    [mysqld]
    log_bin
    server-id=3

修改3台服务器的MySQL的配置文件之后重启服务，3台机器全部重启

[root@mysql-1 ~]# service mysql restart

### 创建同步账户 ###

mysql-1，mysql-2为主节点，需要创建，replication账户，mysql-2作为slave做完3M之后会自动同步

[root@mysql-1 ~]# mysql -u root -pab123（密码以自己设置的为准）
    mysql>use mysql;
    mysql>select user,host from user;
    mysql> select host,user from user;
    +-----------+---------------+
    | host      | user          |
    +-----------+---------------+
    | %         | root          |
    | localhost | mysql.session |
    | localhost | mysql.sys     |
    +-----------+---------------+
    3 rows in set (0.00 sec)
    mysql>set global validate_password_policy=0;
    mysql>set global validate_password_length=6;
    mysql> create user replication@'%' identified by '123456';
    mysql> grant all privileges on *.* to replication@'%' identified by '123456';

注意有的时候登陆mysql数据的时候会提示以下错误，需要我们携带主机地址登陆

[root@mysql-1 ~]# mysql -u root -pab123
    mysql: [Warning] Using a password on the command line interface can be insecure.
    ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

此时只需要携带ip登陆即可

[root@mysql-1 ~]# mysql -u root -h 127.0.0.1 -pab123 
    mysql: [Warning] Using a password on the command line interface can be insecure.
    Welcome to the MySQL monitor.  Commands end with ; or \g.
    Your MySQL connection id is 47441
    Server version: 5.7.24-log MySQL Community Server (GPL)
    
    Copyright (c) 2000, 2018, 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>

### 查看master状态 ###

#### mysql-1 ####

mysql> show master status
        -> ;
    +--------------------+----------+--------------+------------------+-------------------+
    | File               | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
    +--------------------+----------+--------------+------------------+-------------------+
    | mysql-1-bin.000001 |      154 |              |                  |                   |
    +--------------------+----------+--------------+------------------+-------------------+
    1 row in set (0.00 sec)

#### mysql-2 ####

这里最主要的信息就是查看File和Position信息，然后分别在mysql-1,mysql-2,mysql-3中设计主

### 设置主从同步 ###

#### mysql-1 (主) ####

mysql> change master to master_host='192.168.38.102',master_user='replication',master_password='123456',master_log_file='mysql-2-bin.000001',master_log_pos=695;
    mysql> start slave;

#### mysql-2（主） ####

change master to master_host='192.168.38.101',master_user='replication',master_password='123456',master_log_file='mysql-1-bin.000001',master_log_pos=154;
    mysql> start slave;

#### mysql-3（从） ####

change master to master_host='192.168.38.101',master_user='replication',master_password='123456',master_log_file='mysql-1-bin.000001',master_log_pos=154;
    mysql> start slave;

#### 查看slave状态 ####

mysql> show slave status\G
    *************************** 1. row ***************************
                   Slave_IO_State: 
                      Master_Host: 192.168.38.102
                      Master_User: replication
                      Master_Port: 3306
                    Connect_Retry: 60
                  Master_Log_File: mysql-2-bin.000001
              Read_Master_Log_Pos: 695
                   Relay_Log_File: mysql-1-relay-bin.000001
                    Relay_Log_Pos: 4
            Relay_Master_Log_File: mysql-2-bin.000001
                 Slave_IO_Running: No
                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: 695
                  Relay_Log_Space: 154
                  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: NULL
    Master_SSL_Verify_Server_Cert: No
                    Last_IO_Errno: 1593
                    Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work.
                   Last_SQL_Errno: 0
                   Last_SQL_Error: 
      Replicate_Ignore_Server_Ids: 
                 Master_Server_Id: 2
                      Master_UUID: 
                 Master_Info_File: /usr/local/mysql/data/master.info
                        SQL_Delay: 0
              SQL_Remaining_Delay: NULL
          Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
               Master_Retry_Count: 86400
                      Master_Bind: 
          Last_IO_Error_Timestamp: 201230 17:21:33
         Last_SQL_Error_Timestamp: 
                   Master_SSL_Crl: 
               Master_SSL_Crlpath: 
               Retrieved_Gtid_Set: 
                Executed_Gtid_Set: 
                    Auto_Position: 0
             Replicate_Rewrite_DB: 
                     Channel_Name: 
               Master_TLS_Version: 
    1 row in set (0.00 sec)

现在对主要配置信息做一下解读

<table> 
 <thead> 
  <tr> 
   <th>参数名称</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>Master_Host</td> 
   <td>master所在主机，也就是本机作为slave需要从那台机器同步</td> 
  </tr> 
  <tr> 
   <td>Master_User</td> 
   <td>同步使用的账号</td> 
  </tr> 
  <tr> 
   <td>Master_Port</td> 
   <td>端口号</td> 
  </tr> 
  <tr> 
   <td>Master_Log_File</td> 
   <td>master日志文件，需要我们使用 show master status查看</td> 
  </tr> 
  <tr> 
   <td>Read_Master_Log_Pos</td> 
   <td>同步开始的偏移量，需要我们使用 show master status查看</td> 
  </tr> 
  <tr> 
   <td>Slave_IO_Running</td> 
   <td>从的IO运行状态 NO为运行异常</td> 
  </tr> 
  <tr> 
   <td>Slave_SQL_Running</td> 
   <td>从的SQL运行状态 NO为运行异常</td> 
  </tr> 
 </tbody> 
</table>

从上面的信息我们可以看到Slave\_IO\_Running出现了一次，这类问题的原因是我们每一个mysql需要有一个唯一的UUID，因为我们是从虚拟机的镜像直接创建的虚拟机MySQL的uuid相同导致的，需要做一下修改

[root@mysql-3 ~]# vim /usr/local/mysql/data/auto.cnf
    [auto]
    server-uuid=5fe078e2-4976-11eb-b36e-000c29eb5a8b

auto.cnf所在的路径以实际的mysql安装目录为准也可以直接查找该文件

[root@mysql-3 ~]# find / -name auto.cnf
    /usr/local/mysql/data/auto.cnf

重启之后再次查看slave的状态

mysql> show slave status\G;
    *************************** 1. row ***************************
                   Slave_IO_State: Waiting for master to send event
                      Master_Host: 192.168.38.102
                      Master_User: replication
                      Master_Port: 3306
                    Connect_Retry: 60
                  Master_Log_File: mysql-2-bin.000004
              Read_Master_Log_Pos: 154
                   Relay_Log_File: mysql-1-relay-bin.000010
                    Relay_Log_Pos: 371
            Relay_Master_Log_File: mysql-2-bin.000004
                 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: 154
                  Relay_Log_Space: 748
                  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: 2
                      Master_UUID: 5fe078e2-4976-11eb-b36e-000c29eb5a8c
                 Master_Info_File: /usr/local/mysql/data/master.info
                        SQL_Delay: 0
              SQL_Remaining_Delay: NULL
          Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
               Master_Retry_Count: 86400
                      Master_Bind: 
          Last_IO_Error_Timestamp: 
         Last_SQL_Error_Timestamp: 
                   Master_SSL_Crl: 
               Master_SSL_Crlpath: 
               Retrieved_Gtid_Set: 
                Executed_Gtid_Set: 
                    Auto_Position: 0
             Replicate_Rewrite_DB: 
                     Channel_Name: 
               Master_TLS_Version: 
    1 row in set (0.01 sec)
    
    ERROR: 
    No query specified

此时Slave\_IO\_Running就变成了yes

### 安装MMM ###

3台机器均需要安装，为了方便复制我在最后加了一个回车，这个4条安装命令都能够执行了

yum -y install epel-release
    wget http://rpms.remirepo.net/enterprise/remi-release-7.rpm
    rpm -Uvh remi-release-7.rpm
    yum install -y mysql-mmm-agent.noarch

### 安装3M监控 ###

只需要在mysql-1上安装就可以，当然都安装也可以，安装的文件夹为/etc/mysql-mmm

[root@mysql-1 ~]# yum install -y mysql-mmm*

### 配置3M ###

3台机器均需要配置 mmm\_agent.conf，mmm\_common.conf

[root@mysql-3 mysql-mmm]# ll
    total 36
    -rw-r-----. 1 root root   230 Dec 30 17:58 mmm_agent.conf
    -rw-r-----. 1 root root   755 Dec 30 18:43 mmm_common.conf
    -rw-r-----. 1 root root   680 May  5  2018 mmm_mon.conf
    -rw-r-----. 1 root root   827 May  5  2018 mmm_mon_log.conf
    -rw-r--r--. 1 root root  1432 May  5  2018 mmm_tools.conf
    -rw-r--r--. 1 root root 12417 Dec 30 18:02 select

#### mmm\_common.conf 公共配置文件 ####

配置文件三台机器配置相同

[root@mysql-3 mysql-mmm]# vim mmm_common.conf
    
    active_master_role      writer
    
    <host default>
        cluster_interface       ens33
        pid_path                /run/mysql-mmm-agent.pid
        bin_path                /usr/libexec/mysql-mmm/
        replication_user        replication
        replication_password    123456
        agent_user              agent
        agent_password          123456
    </host>
    
    <host db1>
        ip      192.168.38.101
        mode    master
        peer    db2
    </host>
    
    <host db2>
        ip      192.168.38.102
        mode    master
        peer    db1
    </host>
    
    <host db3>
        ip      192.168.38.103
        mode    slave
    </host>
    
    <role writer>
        hosts   db1, db2
        ips     192.168.38.88
        mode    exclusive
    </role>
    
    <role reader>
        hosts   db1, db2, db3
        ips     192.168.38.66
        mode    balanced
    </role>

从配置文件可以看出我们还需要创建一个agent\_user账户 名称为 agent，密码为123456（生产以实际为准）这个我们在配置完成3m配置文件之后统一创建

#### mmm\_agent.conf 代理配置文件 ####

这里需要指明db的名称,只需要修改 this db。。。

mysql-1

[root@mysql-1 mysql-mmm]# vim mmm_agent.conf
    
    include mmm_common.conf
    
    # The 'this' variable refers to this server. Proper operation requires
    # that 'this' server (db1 by default), as well as all other servers, have the
    # proper IP addresses set in mmm_common.conf.
    this db1

mysql-2

[root@mysql-2 mysql-mmm]# vim mmm_agent.conf
    
    include mmm_common.conf
    
    # The 'this' variable refers to this server. Proper operation requires
    # that 'this' server (db1 by default), as well as all other servers, have the
    # proper IP addresses set in mmm_common.conf.
    this db2

mysql-3

[root@mysql-3 mysql-mmm]# vim mmm_agent.conf
    
    include mmm_common.conf
    
    # The 'this' variable refers to this server. Proper operation requires
    # that 'this' server (db1 by default), as well as all other servers, have the
    # proper IP addresses set in mmm_common.conf.
    this db3

#### 监控配置文件 ####

[root@mysql-1 mysql-mmm]# vim mmm_mon.conf 
    
    include mmm_common.conf
    
    <monitor>
        ip                  127.0.0.1
        pid_path            /run/mysql-mmm-monitor.pid
        bin_path            /usr/libexec/mysql-mmm
        status_path         /var/lib/mysql-mmm/mmm_mond.status
        ping_ips            192.168.38.101,192.168.38.102,192.168.38.103
        auto_set_online     60
    
        # The kill_host_bin does not exist by default, though the monitor will
        # throw a warning about it missing. See the section 5.10 "Kill Host
        # Functionality" in the PDF documentation.
        #
        # kill_host_bin /usr/libexec/mysql-mmm/monitor/kill_host
        #
    </monitor>
    
    <host default>
        monitor_user        monitor
        monitor_password    123456
    </host>
    
    debug 0

从配置文件中可以看到ping ips就是我们需要监控的主机节点  
还可以看到需要在创建一个监控账号monitor\_user，账号名称为monitor，密码为123456  
到此为止我们的3m的安装工作完成

### 创建3M代理&监控账号 ###

mysql>set global validate_password_policy=0;
    mysql>set global validate_password_length=6;
    mysql> create user agent@'%' identified by '123456';
    mysql> grant all privileges on *.* to agent@'%' identified by '123456';
    mysql> create user monitor@'%' identified by '123456';
    mysql> grant all privileges on *.* to monitor@'%' identified by '123456';

### 启动3M ###

启动和查看3M状态，所有节点

[root@mysql-1 mysql-mmm]# systemctl start mysql-mmm-agent
    [root@mysql-1 mysql-mmm]# systemctl status mysql-mmm-agent
    ● mysql-mmm-agent.service - MySQL MMM agent
       Loaded: loaded (/usr/lib/systemd/system/mysql-mmm-agent.service; disabled; vendor preset: disabled)
       Active: active (running) since Wed 2020-12-30 18:18:48 CST; 9s ago
      Process: 1752 ExecStart=/usr/sbin/mmm_agentd (code=exited, status=0/SUCCESS)
     Main PID: 1754 (mmm_agentd)
       CGroup: /system.slice/mysql-mmm-agent.service
               ├─1754 mmm_agentd
               └─1755 mmm_agentd
    
    Dec 30 18:18:48 mysql-1 systemd[1]: Starting MySQL MMM agent...
    Dec 30 18:18:48 mysql-1 systemd[1]: Started MySQL MMM agent.

### 启动3M监控 ###

启动和查看3M监控，仅在mysql-1节点即可

[root@mysql-1 ~]# systemctl start mysql-mmm-monitor
    [root@mysql-1 ~]# systemctl status mysql-mmm-monitor
    ● mysql-mmm-monitor.service - MySQL MMM Monitor
       Loaded: loaded (/usr/lib/systemd/system/mysql-mmm-monitor.service; disabled; vendor preset: disabled)
       Active: active (running) since Wed 2020-12-30 18:19:37 CST; 12s ago
      Process: 1770 ExecStart=/usr/sbin/mmm_mond (code=exited, status=0/SUCCESS)
     Main PID: 1772 (mmm_mond)
       CGroup: /system.slice/mysql-mmm-monitor.service
               ├─1772 mmm_mond
               ├─1773 mmm_mond
               ├─1785 perl /usr/libexec/mysql-mmm/monitor/checker ping_ip
               ├─1788 perl /usr/libexec/mysql-mmm/monitor/checker mysql
               ├─1790 perl /usr/libexec/mysql-mmm/monitor/checker ping
               ├─1792 perl /usr/libexec/mysql-mmm/monitor/checker rep_backlog
               └─1794 perl /usr/libexec/mysql-mmm/monitor/checker rep_threads
    
    Dec 30 18:19:37 mysql-1 systemd[1]: Starting MySQL MMM Monitor...
    Dec 30 18:19:37 mysql-1 systemd[1]: Started MySQL MMM Monitor.

### 验证 ###

1.需要验证我们的主从同步是否成功也就是之前创建的账号在mysql-3节点中是否存在

[root@mysql-3 mysql-mmm]# mysql -uroot -h 127.0.0.1 -pab123
    mysql: [Warning] Using a password on the command line interface can be insecure.
    Welcome to the MySQL monitor.  Commands end with ; or \g.
    Your MySQL connection id is 32347
    Server version: 5.7.24-log MySQL Community Server (GPL)
    
    Copyright (c) 2000, 2018, 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> use mysql
    Reading table information for completion of table and column names
    You can turn off this feature to get a quicker startup with -A
    
    Database changed
    mysql> select user,host from user;
    +---------------+-----------+
    | user          | host      |
    +---------------+-----------+
    | agent         | %         |
    | monitor       | %         |
    | root          | %         |
    | mysql.session | localhost |
    | mysql.sys     | localhost |
    +---------------+-----------+
    5 rows in set (0.01 sec)

可以看到我们创建的账号已经成功的同步到mysql-3节点了

#### 验证VIP写 ####

[root@mysql-1 mysql-mmm]# ping 192.168.38.88
    PING 192.168.38.88 (192.168.38.88) 56(84) bytes of data.
    64 bytes from 192.168.38.88: icmp_seq=1 ttl=64 time=0.024 ms
    64 bytes from 192.168.38.88: icmp_seq=2 ttl=64 time=0.058 ms
    ^C
    --- 192.168.38.88 ping statistics ---
    2 packets transmitted, 2 received, 0% packet loss, time 1001ms
    rtt min/avg/max/mdev = 0.024/0.041/0.058/0.017 ms
    [root@mysql-1 mysql-mmm]# ip addr
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet 127.0.0.1/8 scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host 
           valid_lft forever preferred_lft forever
    2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
        link/ether 00:0c:29:eb:5a:8a brd ff:ff:ff:ff:ff:ff
        inet 192.168.38.101/24 brd 192.168.38.255 scope global noprefixroute ens33
           valid_lft forever preferred_lft forever
        inet 192.168.38.88/32 scope global ens33
           valid_lft forever preferred_lft forever
        inet6 fe80::de20:8b11:4e06:efc7/64 scope link noprefixroute 
           valid_lft forever preferred_lft forever

可以看到vip可以正常通讯，经过查看在mysql-1节点上

### 验证VIP读 ###

[root@mysql-2 ~]# ping 192.168.38.66
    PING 192.168.38.66 (192.168.38.66) 56(84) bytes of data.
    64 bytes from 192.168.38.66: icmp_seq=1 ttl=64 time=0.032 ms
    64 bytes from 192.168.38.66: icmp_seq=2 ttl=64 time=0.052 ms
    ^C
    --- 192.168.38.66 ping statistics ---
    2 packets transmitted, 2 received, 0% packet loss, time 999ms
    rtt min/avg/max/mdev = 0.032/0.042/0.052/0.010 ms
    [root@mysql-2 ~]# ip addr
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet 127.0.0.1/8 scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host 
           valid_lft forever preferred_lft forever
    2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
        link/ether 00:0c:29:a2:40:61 brd ff:ff:ff:ff:ff:ff
        inet 192.168.38.102/24 brd 192.168.38.255 scope global noprefixroute ens33
           valid_lft forever preferred_lft forever
        inet 192.168.38.66/32 scope global ens33
           valid_lft forever preferred_lft forever
        inet6 fe80::f7ef:68e8:1ce4:d29a/64 scope link noprefixroute 
           valid_lft forever preferred_lft forever

可以看到vip读在mysql-2节点

### 故障转移验证 ###

我们现在正常状态下验证是否可以登录mysql数据库  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzE1OTAzOQ_size_16_color_FFFFFF_t_70]  
这时候我们把mysql-1节点重启

[root@mysql-1 mysql-mmm]# reboot

此时我们再次连接  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzE1OTAzOQ_size_16_color_FFFFFF_t_70 1]  
结果发现不能连接  
将mysql-1节点的3M代理和监控打开之后发现可以VIP又回来了  
于是我会议可能是mysql-1节点的监控造成的，我将mysql-2节点关闭  
此时我发现读的VIP发生了漂移

[root@mysql-3 mysql-mmm]# ip addr
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet 127.0.0.1/8 scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host 
           valid_lft forever preferred_lft forever
    2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
        link/ether 00:0c:29:15:72:19 brd ff:ff:ff:ff:ff:ff
        inet 192.168.38.103/24 brd 192.168.38.255 scope global noprefixroute ens33
           valid_lft forever preferred_lft forever
        inet 192.168.38.66/32 scope global ens33
           valid_lft forever preferred_lft forever
        inet6 fe80::e6f5:e229:89d0:57dc/64 scope link noprefixroute 
           valid_lft forever preferred_lft forever

因此我在mysql-2节点也开启了监控

[root@mysql-2 mysql-mmm]# systemctl start mysql-mmm-agent
    [root@mysql-2 mysql-mmm]# systemctl start mysql-mmm-monitor

此时再次重启mysql-1节点  
查看监控状态

[root@mysql-2 ~]# mmm_control show
      db1(192.168.38.101) master/ONLINE. Roles: 
      db2(192.168.38.102) master/ONLINE. Roles: writer(192.168.38.88)
      db3(192.168.38.103) slave/ONLINE. Roles: reader(192.168.38.66)

从上面可只VIP的写节点在mysql-2节点  
此时关闭mysql-2节点数据库

[root@mysql-2 ~]# service mysql stop
    Shutting down MySQL............ SUCCESS!
    [root@mysql-2 ~]# mmm_control show
      db1(192.168.38.101) master/ONLINE. Roles: writer(192.168.38.88)
      db2(192.168.38.102) master/HARD_OFFLINE. Roles: 
      db3(192.168.38.103) slave/ONLINE. Roles: reader(192.168.38.66)

此时我们能够看到mysql-2节点已经下线VIP写已经漂移到mysql-1节点上  
mmm\_control show命令只能在开启mysql-mmm-monitor的节点才能查看

**建议我们在搭建3M环境的时候，可以将监控放在非MySQL节点上这样做的好处是，MySQL所在服务器挂掉之后监控扔可使用**

最后我们在启动mysql-2节点数据库，查看写节点是否漂移回来

Starting MySQL. SUCCESS! 
    [root@mysql-2 ~]# mmm_control show
      db1(192.168.38.101) master/ONLINE. Roles: writer(192.168.38.88)
      db2(192.168.38.102) master/AWAITING_RECOVERY. Roles: 
      db3(192.168.38.103) slave/ONLINE. Roles: reader(192.168.38.66)

目前的状态时等待覆盖状态  
大约60s左右就变成正常的状态，写VIP仍然留在mysql-1节点

[root@mysql-2 ~]# mmm_control show
      db1(192.168.38.101) master/ONLINE. Roles: writer(192.168.38.88)
      db2(192.168.38.102) master/ONLINE. Roles: 
      db3(192.168.38.103) slave/ONLINE. Roles: reader(192.168.38.66)

至此3M环境搭建完成

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