MYSQL高可用MYSQL-MMM配置测试

环境: mysql version 5.7.22 on redhat6.4 64bit
         master-db1 192.168.0.104
         master-db2 192.168.0.105
         slave-db3,mysql-mmm-monitor 192.168.0.106
         mysql-mmm写VIP 192.168.0.110 读vip192.168.0.111, 192.168.0.112,192.168.0.113

1. 192.168.0.104 master-db1 与 192.168.0.105 master-db2 主主复制：略过
https://blog.csdn.net/aryoyo/article/details/80616396

192.168.0.104 master-db1 与 192.168.0.106 slave-db3 主从复制：略过
https://blog.csdn.net/aryoyo/article/details/80597947

2.在msater-db1上创建mmm_monitor和mmm_agent的账号，monitor主要是监控服务器的健康和复制状态的，
agent主要是做故障转移或主从切换，比如master-db1 crash后需要修改slave-db3的主为master-db2，所以需
赋予对应权限：
   create user 'mmm_monitor'@'%' identified by '123456';
   grant replication client on *.* to mmm_monitor;
   create user 'mmm_agent'@'%' identified by '123456';
   grant super,replication client,process on *.* to mmm_agent;

3.三台服务器分别安装mysql-mmm-agent，monitor 106上安装mysql-mmm-monitor
rpm -ivh http://mirrors.ustc.edu.cn/fedora/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -ivh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
yum install mysql-mmm-agent
yum install mysql-mmm*
yum安装报错：

 http://download.fedoraproject.org/pub/epel/6/x86_64/repodata/55a73bffdf44e8dfdb2066488144e71e23c8a5d7f727 38e8f935b2a6aa57764d-comps-Everything.x86_64.xml.gz: [Errno 14] problem making ssl connection
Trying other mirror.

解决办法是：
vim /etc/yum.repos.d/epel.repo,先把[epel]的enabled改成0，yum install ca-certificates

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4.mysql-mmm的配置文件
1>三台服务器的/etc/hosts文件配置

192.168.0.104 master-db1
192.168.0.105 master-db2
192.168.0.106 slave-db3

2> 三台服务器上的/etc/mysql-mmm/mmm_common.conf

active_master_role      writer

<host default>
    cluster_interface       eth0
    pid_path                /var/run/mysql-mmm/mmm_agentd.pid
    bin_path                /usr/libexec/mysql-mmm/
    replication_user        replicant
    replication_password    123456
    agent_user              mmm_agent
    agent_password          123456
</host>

<host master-db1>
    ip      192.168.0.104
    mode    master
    peer    master-db2
</host>

<host master-db2>
    ip      192.168.0.105
    mode    master
    peer    master-db1
</host>

<host slave-db3>
    ip      192.168.0.106
    mode    slave
</host>

<role writer>
    hosts   master-db1,master-db2
    ips     192.168.0.110
    mode    exclusive
</role>

<role reader>
    hosts   master-db1,master-db2,slave-db3
    ips     192.168.0.111,192.168.0.112,192.168.0.113
    mode    balanced
</role>

3>3台服务器/etc/mysql-mmm/mmm_agent.conf，每台分别对应自己的名字:

this salve-db3

4>monitor服务器上/etc/mysql-mmm/mmm_mon.conf：

include mmm_common.conf

<monitor>
    ip                  192.168.0.106
    pid_path            /var/run/mysql-mmm/mmm_mond.pid
    bin_path            /usr/libexec/mysql-mmm
    status_path         /var/lib/mysql-mmm/mmm_mond.status
    ping_ips            192.168.0.104,192.168.0.105,192.168.0.106
    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        mmm_monitor
    monitor_password    123456
</host>

5.三台服务分别启动mysql-mmm-agent服务
service mysql-mmm-agent start
monitor服务器上启动mysql-mmm-monitor服务
service mysql-mmm-monitor start

6.monitor服务器上：mmm_control show

[root@rhel64-64bit Desktop]# mmm_control show
  master-db1(192.168.0.104) master/ONLINE. Roles: reader(192.168.0.111), writer(192.168.0.110)
  master-db2(192.168.0.105) master/ONLINE. Roles: reader(192.168.0.112)
  slave-db3(192.168.0.106) slave/ONLINE. Roles: reader(192.168.0.113)

在104的master-db1服务器上ip addr，读写VIP分配成功

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:22:98:4d brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.104/24 brd 192.168.0.255 scope global eth0
    inet 192.168.0.111/32 scope global eth0
    inet 192.168.0.110/32 scope global eth0
    inet6 fe80::20c:29ff:fe22:984d/64 scope link 
       valid_lft forever preferred_lft forever

7.故障转移和切换测试：

1>104 master-db1上停止mysql
service mysqld stop

2>106 monitor上查看集群状态：
[root@rhel64-64bit Desktop]# mmm_control show
master-db1(192.168.0.104) master/HARD_OFFLINE. Roles:
master-db2(192.168.0.105) master/ONLINE. Roles: reader(192.168.0.112), writer(192.168.0.110)
slave-db3(192.168.0.106) slave/ONLINE. Roles: reader(192.168.0.111), reader(192.168.0.113)
可见写VIP已经到了master-db2 105服务器上了，应用不会有感知VIP的漂移的，因为mysql对应用的访问ip是VIP

3>查看slave-db3复制状态，发现master变成了105的master-db2了

mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.0.105
                  Master_User: replicant
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mybinlogg.000014
          Read_Master_Log_Pos: 678
               Relay_Log_File: rhel64-64bit-relay-bin.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mybinlogg.000014
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

4>如果此时把104 服务器msater-db1重启启动，则60s后，查看：
[root@rhel64-64bit Desktop]# mmm_control show
master-db1(192.168.0.104) master/ONLINE. Roles: reader(192.168.0.113)
master-db2(192.168.0.105) master/ONLINE. Roles: reader(192.168.0.112), writer(192.168.0.110)
slave-db3(192.168.0.106) slave/ONLINE. Roles: reader(192.168.0.111)
master-db1重新加入集群，依旧和master-db2互为主主复制关系不需任何操作

8.总结：
mysql-mmm高可用特点：
1>当master-db1 down后，mysql-mmm的写VIP漂到master-db2上，并且自动完成slave-db3到master-db2的主从复制
更改，无需人为干预
2>可以监控从服务器的延迟，并发现超过某个值后，可以把读VIP迁移待其他延迟较小的服务器
mysql-mmm缺点：
1>只能是基于日志pos方式的复制，不支持基于GTID的复制也不支持多线程复制功能
2>master-db1 down后，只能选择master-db2作为新的主，可能master-db2的日志点的还没slave-db3的状态新，这样会导致数据的丢失，主从更改后还可能造成slave-db3的事务的重复提交等问题.

MYSQL高可用MYSQL-MMM配置测试

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