MySQL-MHA高可用（一）-Toy模板网

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目录

🍁同步概念

🍁工作原理

🍃环境拓扑

🍁环境准备

🍂manager

🍂master1

🍂master2

🍂slave

🍃配置半同步复制

🍁master1

🍁master2

🍁slave

🍁查看状态

🍁创建用户并指定主从

🍂master1

🍂master2

🍂slave

🍃配置mysql-mha

🍁配置mha

🍁验证

🍂SSH 有效性验证

🍂集群复制的有效性验证

🍂启动manager

🍂故障转移验证

🍃MHA Manager 端日常操作

🦐博客主页：大虾好吃吗的博客

🦐MySQL专栏：MySQL专栏地址

MHA（Master High Availability）目前在 MySQL 高可用方面是一个相对成熟的解决方案是一套优秀的作为 MySQL 高可用性环境下故障切换和主从提升的高可用软件。

在 MySQL 故障切换过程中，MHA 能做到在 0~30 秒之内自动完成数据库的故障切换操作，并且在进行故障切换的过程中，MHA 能在最大程度上保证数据的一致性，以达到真正意义上的高可用。

该软件由两部分组成：MHA Manager（管理节点）和 MHA Node（数据节点）。MHA Manager 可以单独部署在一台独立的机器上管理多个 master-slave 集群，也可以部署在一台 slave 节点上。MHA Node 运行在每台 MySQL 服务器上，MHA Manager 会定时探测集群中的 master 节点，当 master 出现故障时，它可以自动将最新数据的 slave 提升为新的 master，然后将所有其他的 slave 重新指向新的 master。整个故障转移过程对应用程序完全透明。

MySQL-MHA高可用（一）在 MHA 自动故障切换过程中，MHA 试图从宕机的主服务器上保存二进制日志，最大程度的保证数据的不丢失，但这并不总是可行的。例如，如果主服务器硬件故障或无法通过 ssh 访问，MHA 没法保存二进制日志，只进行故障转移而丢失了最新的数据。使用 MySQL 5.5 的半同步复制，可以大大降低数据丢失的风险。MHA 可以与半同步复制结合起来。如果只有一个 slave 已经收到了最新的二进制日志，MHA 可以将最新的二进制日志应用于其他所有的 slave 服务器上，因此可以保证所有节点的数据一致性。

注意：从MySQL5.5开始，MySQL以插件的形式支持半同步复制。

同步概念

如何理解半同步呢？首先我们来看看异步，全同步的概念：

异步复制（Asynchronous replication） MySQL默认的复制即是异步的，主库在执行完客户端提交的事务后会立即将结果返给给客户端，并不关心从库是否已经接收并处理，这样就会有一个问题，主如果crash掉了，此时主上已经提交的事务可能并没有传到从上，如果此时，强行将从提升为主，可能导致新主上的数据不完整。

全同步复制（Fully synchronous replication）指当主库执行完一个事务，所有的从库都执行了该事务才返回给客户端。因为需要等待所有从库执行完该事务才能返回，所以全同步复制的性能必然会收到严重的影响。

半同步复制（Semisynchronous replication）介于异步复制和全同步复制之间，主库在执行完客户端提交的事务后不是立刻返回给客户端，而是等待至少一个从库接收到并写到relay log中才返回给客户端。相对于异步复制，半同步复制提高了数据的安全性，同时它也造成了一定程度的延迟，这个延迟最少是一个TCP/IP往返的时间。所以，半同步复制最好在低延时的网络中使用。

总结：异步与半同步异同默认情况下MySQL的复制是异步的，Master上所有的更新操作写入Binlog之后并不确保所有的更新都被复制到Slave之上。异步操作虽然效率高，但是在Master/Slave出现问题的时候，存在很高数据不同步的风险，甚至可能丢失数据。 MySQL5.5引入半同步复制功能的目的是为了保证在master出问题的时候，至少有一台Slave的数据是完整的。在超时的情况下也可以临时转入异步复制，保障业务的正常使用，直到一台salve追赶上之后，继续切换到半同步模式。

工作原理

相较于其它HA软件，MHA的目的在于维持MySQL Replication中Master库的高可用性，其最大特点是可以修复多个Slave之间的差异日志，最终使所有Slave保持数据一致，然后从中选择一个充当新的Master，并将其它Slave指向它。

从宕机崩溃的master保存二进制日志事件(binlogevents)。
识别含有最新更新的slave。
应用差异的中继日志(relay log)到其它slave。
应用从master保存的二进制日志事件(binlogevents)。
提升一个slave为新master。
使其它的slave连接新的master进行复制。

目前 MHA 主要支持一主多从的架构，要搭建 MHA, 要求一个复制集群中必须最少有三台数据库服务器，一主二从，即一台充当 master，一台充当备用 master，另外一台充当从库，因为至少需要三台服务器，出于机器成本的考虑，淘宝也在该基础上进行了改造，目前淘宝 TMHA 已经支持一主一从。

环境拓扑

其中master1对外提供写服务，备选master（实际为slave，主机名master2）提供读服务，slave也提供相关的读服务，一旦master1宕机，将会把备选master提升为新的master，slave指向新的master，manager作为管理服务器。生产环境中，是有很多从，从的操作都是一样的，这里以两台slave为例，而备选master也作为slave。

MySQL-MHA高可用（一）

环境准备

1、在配置好IP地址后检查selinux，iptables设置，关闭 selinux ，iptables 服务以便后期主从同步不出错注：时间要同步。

2、在四台机器都配置epel源

[root@manager ~]# wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo

3、建立ssh无交互登录环境

manager

下面四台主机都需要执行互信，通过for循环把公钥传出去。（互信时直接按回车即可，但是传出去需要允许（yes），然后输入对端密码）

[root@manager ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:8zzNm0tUTQ9bw/E9GQ6+1BbJIPOn5iWPsms6suwmFUU root@manager
The key's randomart image is:
+---[RSA 2048]----+
|        .E o o===|
|         .  = +XO|
|        .    +oB=|
|       .    ..= .|
|        S   .= . |
|       . + +o =  |
|      .   +.+o . |
|     ..o . +oo   |
|      ++o.+o=.   |
+----[SHA256]-----+
[root@manager ~]# for i in 20 30 40 50;do ssh-copy-id -i ~/.ssh/id_rsa.pub root@192.168.8.$i;done

master1

[root@master1 ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:cBhASzDVEouISwajm3/j3L3XjLvwYzQzEvkTi2800+k root@master1
The key's randomart image is:
+---[RSA 2048]----+
|o o+*+.          |
|+o +.o.o         |
|+o. o.o ..       |
|o+     oo .      |
|+       S+ + .   |
| .      o % o    |
|  . o   .= %     |
|   + o . oB E    |
|    o . o=++     |
+----[SHA256]-----+
[root@master1 ~]# for i in 20 30 40 50;do ssh-copy-id -i ~/.ssh/id_rsa.pub root@192.168.8.$i;done

master2

[root@master2 ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:MHKw5P1AEBshLUAPUnIKQ/wPtXYAxfMOU/cNErvjZLo root@master2
The key's randomart image is:
+---[RSA 2048]----+
|X*+o@=.  ..      |
|o*++.% . o..     |
|. .o* % ..o o    |
|   o B B  .. .   |
|    + = S=       |
|     . .= .      |
|       . .       |
|        .        |
|       E         |
+----[SHA256]-----+
[root@master2 ~]# for i in 20 30 40 50;do ssh-copy-id -i ~/.ssh/id_rsa.pub root@192.168.8.$i;done

slave

[root@slave ~]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:3RuS1syMJTLHKzqrHLph3xRDuCh7xDU05i6zqfqnFQM root@slave
The key's randomart image is:
+---[RSA 2048]----+
|    +            |
|   + o   .       |
|  E = . o + .    |
| . = +   = %     |
|. * = o S B B    |
| + = o + o . o   |
|. * o +     .    |
| + *.+ o         |
|+.=++.o          |
+----[SHA256]-----+
[root@slave ~]# for i in 20 30 40 50;do ssh-copy-id -i ~/.ssh/id_rsa.pub root@192.168.8.$i;done

测试ssh交互，远程查看各主机名称

[root@manager ~]# for i in 20 30 40 50 ;do ssh 192.168.8.$i hostname;done
manager
master1
master2
slave

4、配置hosts环境

[root@manager ~]# vim /etc/hosts
#插入四行数据
192.168.8.20 manager
192.168.8.30 master1
192.168.8.40 master2
192.168.8.50 slave
[root@manager ~]# for i in 20 30 40 50;do scp /etc/hosts root@192.168.8.$i:/etc/;done
hosts                              100%  240   201.6KB/s   00:00    
hosts                              100%  240   151.9KB/s   00:00    
hosts                              100%  240   160.9KB/s   00:00    
hosts                              100%  240   105.1KB/s   00:00

配置半同步复制

为了尽可能的减少主库硬件损坏宕机造成的数据丢失，因此在配置MHA的同时建议配置成MySQL的半同步复制。注：mysql半同步插件是由谷歌提供，具体位置/usr/local/mysql/lib/plugin/下，一个是master用的semisync_master.so，一个是slave用的semisync_slave.so。如果不清楚Plugin的目录，用下面命令查找。

mysql> show variables like '%plugin_dir%';
+---------------+------------------------------+
| Variable_name | Value                        |
+---------------+------------------------------+
| plugin_dir    | /usr/local/mysql/lib/plugin/ |
+---------------+------------------------------+
1 row in set (0.00 sec)

1、分别在主从节点上安装相关的插件（master, Candicate master,slave）在MySQL上安装插件需要数据库支持动态载入。检查是否支持，用下面命令检测：

mysql> show variables like '%have_dynamic%';
+----------------------+-------+
| Variable_name        | Value |
+----------------------+-------+
| have_dynamic_loading | YES   |
+----------------------+-------+
1 row in set (0.00 sec)

注意：在所有mysql数据库服务器，安装半同步插件(semisync_master.so,semisync_slave.so)

mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';
Query OK, 0 rows affected (0.01 sec)

mysql> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';
Query OK, 0 rows affected (0.01 sec)

使用下面命令查看是否成功

mysql> show plugins;
或者
mysql> select * from information_schema.plugins;

查看半同步信息

mysql> show variables like '%rpl_semi_sync%';
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | OFF        |
| rpl_semi_sync_master_timeout              | 10000      |
| rpl_semi_sync_master_trace_level          | 32         |
| rpl_semi_sync_master_wait_for_slave_count | 1          |
| rpl_semi_sync_master_wait_no_slave        | ON         |
| rpl_semi_sync_master_wait_point           | AFTER_SYNC |
| rpl_semi_sync_slave_enabled               | OFF        |
| rpl_semi_sync_slave_trace_level           | 32         |
+-------------------------------------------+------------+
8 rows in set (0.01 sec)

上面可以看到半同复制插件已经安装，只是还没有启用，所以是off 。

2、修改my.cnf文件，配置主从同步

若主MYSQL服务器已经存在，只是后期才搭建从MYSQL服务器，在置配数据同步前应先将主MYSQL服务器的要同步的数据库拷贝到从MYSQL服务器上（如先在主MYSQL上备份数据库，再用备份在从MYSQL服务器上恢复）

master1

[root@master1 ~]# vim /etc/my.cnf 
server-id = 1
log-bin=mysql-bin
binlog_format=mixed
log-bin-index=mysql-bin.index
rpl_semi_sync_master_enabled=1
rpl_semi_sync_master_timeout=1000
rpl_semi_sync_slave_enabled=1
relay_log_purge=0
relay-log = relay-bin
relay-log-index = slave-relay-bin.index
[root@master1 ~]# systemctl restart mysqld

注：rpl_semi_sync_master_enabled=1 1表是启用，0表示关闭 rpl_semi_sync_master_timeout=10000：毫秒单位，该参数主服务器等待确认消息10秒后，不再等待，变为异步方式。

master2

[root@master2 ~]# vim /etc/my.cnf
server-id = 2
log-bin=mysql-bin
binlog_format=mixed
log-bin-index=mysql-bin.index
relay_log_purge=0
relay-log = relay-bin
relay-log-index = slave-relay-bin.index
rpl_semi_sync_master_enabled=1
rpl_semi_sync_master_timeout=10000
rpl_semi_sync_slave_enabled=1
[root@master2 ~]# systemctl restart mysqld

注：relay_log_purge=0，禁止 SQL 线程在执行完一个 relay log 后自动将其删除，对于MHA场景下，对于某些滞后从库的恢复依赖于其他从库的relay log，因此采取禁用自动删除功能.

slave

[root@slave ~]# vim /etc/my.cnf
server-id = 3
log-bin = mysql-bin
relay-log = relay-bin
relay-log-index = slave-relay-bin.index
read_only = 1
rpl_semi_sync_slave_enabled=1
[root@slave ~]# systemctl restart mysqld

查看状态

查看三台主机的半同步信息

mysql> show variables like '%rpl_semi_sync%';
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | ON         |
| rpl_semi_sync_master_timeout              | 1000       |
| rpl_semi_sync_master_trace_level          | 32         |
| rpl_semi_sync_master_wait_for_slave_count | 1          |
| rpl_semi_sync_master_wait_no_slave        | ON         |
| rpl_semi_sync_master_wait_point           | AFTER_SYNC |
| rpl_semi_sync_slave_enabled               | ON         |
| rpl_semi_sync_slave_trace_level           | 32         |
+-------------------------------------------+------------+
8 rows in set (0.01 sec)

查看三台主机的半同步状态

mysql> show status like '%rpl_semi_sync%';
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 0     |
| Rpl_semi_sync_master_net_avg_wait_time     | 0     |
| Rpl_semi_sync_master_net_wait_time         | 0     |
| Rpl_semi_sync_master_net_waits             | 0     |
| Rpl_semi_sync_master_no_times              | 0     |
| Rpl_semi_sync_master_no_tx                 | 0     |
| Rpl_semi_sync_master_status                | ON    |
| Rpl_semi_sync_master_timefunc_failures     | 0     |
| Rpl_semi_sync_master_tx_avg_wait_time      | 0     |
| Rpl_semi_sync_master_tx_wait_time          | 0     |
| Rpl_semi_sync_master_tx_waits              | 0     |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     |
| Rpl_semi_sync_master_wait_sessions         | 0     |
| Rpl_semi_sync_master_yes_tx                | 0     |
| Rpl_semi_sync_slave_status                 | OFF   |
+--------------------------------------------+-------+
15 rows in set (0.01 sec)

有几个状态参数值得关注：

rpl_semi_sync_master_status ：显示主服务是异步复制模式还是半同步复制模式

rpl_semi_sync_master_clients ：显示有多少个从服务器配置为半同步复制模式

rpl_semi_sync_master_yes_tx ：显示从服务器确认成功提交的数量

rpl_semi_sync_master_no_tx ：显示从服务器确认不成功提交的数量

rpl_semi_sync_master_tx_avg_wait_time ：事务因开启 semi_sync ，平均需要额外等待的时间

rpl_semi_sync_master_net_avg_wait_time ：事务进入等待队列后，到网络平均等待时间

创建用户并指定主从

master1

第一条grant命令是创建一个用于主从复制的帐号，在master1和master2的主机上创建即可。第二条grant命令是创建MHA管理账号，所有mysql服务器上都需要执行。MHA会在配置文件里要求能远程登录到数据库，所以要进行必要的赋权。

mysql> grant replication slave on *.* to mharep@'192.168.8.%' identified by '123';
Query OK, 0 rows affected, 1 warning (1.00 sec)

mysql> grant all privileges on *.* to manager@'192.168.8.%' identified by '123';
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000005 |      742 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

master2

mysql> grant replication slave on *.* to mharep@'192.168.8.%' identified by '123';
Query OK, 0 rows affected, 1 warning (10.01 sec)

mysql> grant all privileges on *.* to manager@'192.168.8.%' identified by '123';
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> change master to
    -> master_host='192.168.8.30',
    -> master_port=3306,
    -> master_user='mharep',
    -> master_password='123',
    -> master_log_file='mysql-bin.000005',
    -> master_log_pos=742;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

查看从（master2）的状态（切记不要搞混，master2也是从），以下两个值必须为yes,代表从服务器能正常连接主服务器 Slave_IO_Running:Yes,Slave_SQL_Running:Yes

MySQL-MHA高可用（一）

slave

mysql> grant all privileges on *.* to manager@'192.168.8.%' identified by '123';
Query OK, 0 rows affected, 1 warning (0.04 sec)

mysql> change master to
    -> master_host='192.168.8.30',
    -> master_port=3306,
    -> master_user='mharep',
    -> master_password='123',
    -> master_log_file='mysql-bin.000005',
    -> master_log_pos=742;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

查看从的状态，以下两个值必须为yes,代表从服务器能正常连接主服务器 Slave_IO_Running:Yes Slave_SQL_Running:Yes

MySQL-MHA高可用（一）

查看master1半同步状态

mysql> show status like '%rpl_semi_sync%';
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 2     |
| Rpl_semi_sync_master_net_avg_wait_time     | 0     |
| Rpl_semi_sync_master_net_wait_time         | 0     |
| Rpl_semi_sync_master_net_waits             | 0     |
| Rpl_semi_sync_master_no_times              | 1     |
| Rpl_semi_sync_master_no_tx                 | 2     |
| Rpl_semi_sync_master_status                | ON    |
| Rpl_semi_sync_master_timefunc_failures     | 0     |
| Rpl_semi_sync_master_tx_avg_wait_time      | 0     |
| Rpl_semi_sync_master_tx_wait_time          | 0     |
| Rpl_semi_sync_master_tx_waits              | 0     |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     |
| Rpl_semi_sync_master_wait_sessions         | 0     |
| Rpl_semi_sync_master_yes_tx                | 0     |
| Rpl_semi_sync_slave_status                 | OFF   |
+--------------------------------------------+-------+
15 rows in set (0.01 sec)

配置mysql-mha

manager需要安装node包和manager包，data节点包括原有的MySQL复制结构中的主机，至少3台，即1主2从，当masterfailover后，还能保证主从结构；只需安装node包。manager server：运行监控脚本，负责monitoring 和 auto-failover；

1、在所有主机上安装mha所依赖的软件包。

[root@manager ~]# yum -y install perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-Config-IniFiles ncftp perl-Params-Validate perl-CPAN perl-Test-Mock-LWP.noarch perl-LWP-Authen-Negotiate.noarch perl-devel perl-ExtUtils-CBuilder perl-ExtUtils-MakeMaker

2、在管理节点（manager）需要两个都安装：mha4mysql-node-0.56.tar.gz和mha4mysql-manager-0.56.tar.gz ，在另外三台数据库节点只要安装MHA的node节点。

软件下载 yoshinorim (Yoshinori Matsunobu) · GitHub

管理节点安装mha4mysql-manager-0.58.tar.gz

[root@manager ~]# tar zxf mha4mysql-manager-0.58.tar.gz 
[root@manager ~]# cd mha4mysql-manager-0.58/
[root@manager mha4mysql-manager-0.58]# perl Makefile.PL 
[root@manager mha4mysql-manager-0.58]# make && make install
[root@manager mha4mysql-manager-0.58]# mkdir /etc/masterha
[root@manager mha4mysql-manager-0.58]# mkdir -p /masterha/app1
[root@manager mha4mysql-manager-0.58]# mkdir /scripts
[root@manager mha4mysql-manager-0.58]# cp samples/conf/* /etc/masterha/
[root@manager mha4mysql-manager-0.58]# cp samples/scripts/* /scripts

注意：在所有数据库（包括管理节点的四台服务器）上安装mha4mysql-node-0.56.tar.gz

[root@manager ~]# tar zxf mha4mysql-node-0.58.tar.gz 
[root@manager ~]# cd mha4mysql-node-0.58/
[root@manager mha4mysql-node-0.58]# perl Makefile.PL
[root@manager mha4mysql-node-0.58]# make && make install

配置mha

与绝大多数Linux应用程序类似，MHA的正确使用依赖于合理的配置文件。MHA的配置文件与mysql的my.cnf文件配置相似，采取的是param=value的方式来配置，配置文件位于管理节点，通常包括每一个mysql server的主机名，mysql用户名，密码，工作目录等等。编辑/etc/masterha/app1.conf，内容如下：

[root@manager ~]# vim /etc/masterha/app1.cnf 
[server default]
manager_workdir=/masterha/app1
manager_log=/masterha/app1/manager.log
user=manager
password=123
ssh_user=root
repl_user=mharep
repl_password=123
ping_interval=1

[server1]
hostname=192.168.8.30
port=3306
master_binlog_dir=/usr/local/mysql/data
candidate_master=1

[server2]
hostname=192.168.8.40
port=3306
master_binlog_dir=/usr/local/mysql/data
candidate_master=1

[server3]
hostname=192.168.8.50
port=3306
master_binlog_dir=/usr/local/mysql/data
no_master=1

配关配置项的解释如下：

manager_workdir=/masterha/app1 #设置manager的工作目录

manager_log=/masterha/app1/manager.log #设置manager的日志

user=manager #设置监控用户manager

password=123 #监控用户manager的密码

ssh_user=root #ssh连接用户

repl_user=mharep #主从复制用户

repl_password=123 #主从复制用户密码

ping_interval=1 #设置监控主库，发送ping包的时间间隔，默认是3秒，尝试三次没有回应的时候自动进行

railover master_binlog_dir=/usr/local/mysql/data #设置master 保存binlog的位置，以便MHA可以找到master的日志，我这里的也就是mysql的数据目录

candidate_master=1 #设置为候选master，如果设置该参数以后，发生主从切换以后将会将此从库提升为主库

验证

SSH 有效性验证

[root@manager ~]# masterha_check_ssh --global_conf=/etc/masterha/masterha_default.cnf --conf=/etc/masterha/app1.cnf
Tue Apr  4 13:44:58 2023 - [info] Reading default configuration from /etc/masterha/masterha_default.cnf..
Tue Apr  4 13:44:58 2023 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Tue Apr  4 13:44:58 2023 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Tue Apr  4 13:44:58 2023 - [info] Starting SSH connection tests..
Tue Apr  4 13:45:01 2023 - [debug] 
Tue Apr  4 13:44:59 2023 - [debug]  Connecting via SSH from root@192.168.8.50(192.168.8.50:22) to root@192.168.8.30(192.168.8.30:22)..
Tue Apr  4 13:45:00 2023 - [debug]   ok.
Tue Apr  4 13:45:00 2023 - [debug]  Connecting via SSH from root@192.168.8.50(192.168.8.50:22) to root@192.168.8.40(192.168.8.40:22)..
Tue Apr  4 13:45:00 2023 - [debug]   ok.
Tue Apr  4 13:45:01 2023 - [debug] 
Tue Apr  4 13:44:59 2023 - [debug]  Connecting via SSH from root@192.168.8.40(192.168.8.40:22) to root@192.168.8.30(192.168.8.30:22)..
Tue Apr  4 13:44:59 2023 - [debug]   ok.
Tue Apr  4 13:44:59 2023 - [debug]  Connecting via SSH from root@192.168.8.40(192.168.8.40:22) to root@192.168.8.50(192.168.8.50:22)..
Tue Apr  4 13:45:00 2023 - [debug]   ok.
Tue Apr  4 13:45:01 2023 - [debug] 
Tue Apr  4 13:44:58 2023 - [debug]  Connecting via SSH from root@192.168.8.30(192.168.8.30:22) to root@192.168.8.40(192.168.8.40:22)..
Tue Apr  4 13:44:59 2023 - [debug]   ok.
Tue Apr  4 13:44:59 2023 - [debug]  Connecting via SSH from root@192.168.8.30(192.168.8.30:22) to root@192.168.8.50(192.168.8.50:22)..
Tue Apr  4 13:45:00 2023 - [debug]   ok.
Tue Apr  4 13:45:01 2023 - [info] All SSH connection tests passed successfully.

集群复制的有效性验证

所有mysql必须都启动，验证成功的话会自动识别出所有服务器和主从状况注：验证成功的话会自动识别出所有服务器和主从状况在验证时，若遇到这个错误：Can't exec "mysqlbinlog" ...... 解决方法是在所有服务器上执行：

ln -s /usr/local/mysql/bin/* /usr/local/bin/

[root@manager ~]# masterha_check_repl --global_conf=/etc/masterha/masterha_default.cnf --conf=/etc/masterha/app1.cnf
Tue Apr  4 13:48:03 2023 - [info] Reading default configuration from /etc/masterha/masterha_default.cnf..
Tue Apr  4 13:48:03 2023 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Tue Apr  4 13:48:03 2023 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Tue Apr  4 13:48:03 2023 - [info] MHA::MasterMonitor version 0.58.
Tue Apr  4 13:48:04 2023 - [info] GTID failover mode = 0
Tue Apr  4 13:48:04 2023 - [info] Dead Servers:
Tue Apr  4 13:48:04 2023 - [info] Alive Servers:
Tue Apr  4 13:48:04 2023 - [info]   192.168.8.30(192.168.8.30:3306)
Tue Apr  4 13:48:04 2023 - [info]   192.168.8.40(192.168.8.40:3306)
Tue Apr  4 13:48:04 2023 - [info]   192.168.8.50(192.168.8.50:3306)
Tue Apr  4 13:48:04 2023 - [info] Alive Slaves:
Tue Apr  4 13:48:04 2023 - [info]   192.168.8.40(192.168.8.40:3306)  Version=5.7.40-log (oldest major version between slaves) log-bin:enabled
Tue Apr  4 13:48:04 2023 - [info]     Replicating from 192.168.8.30(192.168.8.30:3306)
Tue Apr  4 13:48:04 2023 - [info]     Primary candidate for the new Master (candidate_master is set)
Tue Apr  4 13:48:04 2023 - [info]   192.168.8.50(192.168.8.50:3306)  Version=5.7.40-log (oldest major version between slaves) log-bin:enabled
Tue Apr  4 13:48:04 2023 - [info]     Replicating from 192.168.8.30(192.168.8.30:3306)
Tue Apr  4 13:48:04 2023 - [info]     Not candidate for the new Master (no_master is set)
Tue Apr  4 13:48:04 2023 - [info] Current Alive Master: 192.168.8.30(192.168.8.30:3306)
Tue Apr  4 13:48:04 2023 - [info] Checking slave configurations..
Tue Apr  4 13:48:04 2023 - [info]  read_only=1 is not set on slave 192.168.8.40(192.168.8.40:3306).
Tue Apr  4 13:48:04 2023 - [warning]  relay_log_purge=0 is not set on slave 192.168.8.50(192.168.8.50:3306).
Tue Apr  4 13:48:04 2023 - [info] Checking replication filtering settings..
Tue Apr  4 13:48:04 2023 - [info]  binlog_do_db= , binlog_ignore_db= 
Tue Apr  4 13:48:04 2023 - [info]  Replication filtering check ok.
Tue Apr  4 13:48:04 2023 - [info] GTID (with auto-pos) is not supported
Tue Apr  4 13:48:04 2023 - [info] Starting SSH connection tests..
Tue Apr  4 13:48:07 2023 - [info] All SSH connection tests passed successfully.
Tue Apr  4 13:48:07 2023 - [info] Checking MHA Node version..
Tue Apr  4 13:48:07 2023 - [info]  Version check ok.
Tue Apr  4 13:48:07 2023 - [info] Checking SSH publickey authentication settings on the current master..
Tue Apr  4 13:48:08 2023 - [info] HealthCheck: SSH to 192.168.8.30 is reachable.
Tue Apr  4 13:48:08 2023 - [info] Master MHA Node version is 0.58.
Tue Apr  4 13:48:08 2023 - [info] Checking recovery script configurations on 192.168.8.30(192.168.8.30:3306)..
Tue Apr  4 13:48:08 2023 - [info]   Executing command: save_binary_logs --command=test --start_pos=4 --binlog_dir=/usr/local/mysql/data --output_file=/data/log/masterha/save_binary_logs_test --manager_version=0.58 --start_file=mysql-bin.000005 
Tue Apr  4 13:48:08 2023 - [info]   Connecting to root@192.168.8.30(192.168.8.30:22).. 
  Creating /data/log/masterha if not exists..    ok.
  Checking output directory is accessible or not..
   ok.
  Binlog found at /usr/local/mysql/data, up to mysql-bin.000005
Tue Apr  4 13:48:08 2023 - [info] Binlog setting check done.
Tue Apr  4 13:48:08 2023 - [info] Checking SSH publickey authentication and checking recovery script configurations on all alive slave servers..
Tue Apr  4 13:48:08 2023 - [info]   Executing command : apply_diff_relay_logs --command=test --slave_user='manager' --slave_host=192.168.8.40 --slave_ip=192.168.8.40 --slave_port=3306 --workdir=/data/log/masterha --target_version=5.7.40-log --manager_version=0.58 --relay_log_info=/usr/local/mysql/data/relay-log.info  --relay_dir=/usr/local/mysql/data/  --slave_pass=xxx
Tue Apr  4 13:48:08 2023 - [info]   Connecting to root@192.168.8.40(192.168.8.40:22).. 
Creating directory /data/log/masterha.. done.
  Checking slave recovery environment settings..
    Opening /usr/local/mysql/data/relay-log.info ... ok.
    Relay log found at /usr/local/mysql/data, up to relay-bin.000002
    Temporary relay log file is /usr/local/mysql/data/relay-bin.000002
    Checking if super_read_only is defined and turned on.. not present or turned off, ignoring.
    Testing mysql connection and privileges..
mysql: [Warning] Using a password on the command line interface can be insecure.
 done.
    Testing mysqlbinlog output.. done.
    Cleaning up test file(s).. done.
Tue Apr  4 13:48:09 2023 - [info]   Executing command : apply_diff_relay_logs --command=test --slave_user='manager' --slave_host=192.168.8.50 --slave_ip=192.168.8.50 --slave_port=3306 --workdir=/data/log/masterha --target_version=5.7.40-log --manager_version=0.58 --relay_log_info=/usr/local/mysql/data/relay-log.info  --relay_dir=/usr/local/mysql/data/  --slave_pass=xxx
Tue Apr  4 13:48:09 2023 - [info]   Connecting to root@192.168.8.50(192.168.8.50:22).. 
Creating directory /data/log/masterha.. done.
  Checking slave recovery environment settings..
    Opening /usr/local/mysql/data/relay-log.info ... ok.
    Relay log found at /usr/local/mysql/data, up to relay-bin.000002
    Temporary relay log file is /usr/local/mysql/data/relay-bin.000002
    Checking if super_read_only is defined and turned on.. not present or turned off, ignoring.
    Testing mysql connection and privileges..
mysql: [Warning] Using a password on the command line interface can be insecure.
 done.
    Testing mysqlbinlog output.. done.
    Cleaning up test file(s).. done.
Tue Apr  4 13:48:09 2023 - [info] Slaves settings check done.
Tue Apr  4 13:48:09 2023 - [info] 
192.168.8.30(192.168.8.30:3306) (current master)
 +--192.168.8.40(192.168.8.40:3306)
 +--192.168.8.50(192.168.8.50:3306)

Tue Apr  4 13:48:09 2023 - [info] Checking replication health on 192.168.8.40..
Tue Apr  4 13:48:09 2023 - [info]  ok.
Tue Apr  4 13:48:09 2023 - [info] Checking replication health on 192.168.8.50..
Tue Apr  4 13:48:09 2023 - [info]  ok.
Tue Apr  4 13:48:09 2023 - [warning] master_ip_failover_script is not defined.
Tue Apr  4 13:48:09 2023 - [warning] shutdown_script is not defined.
Tue Apr  4 13:48:09 2023 - [info] Got exit code 0 (Not master dead).

MySQL Replication Health is OK.

启动manager

注：在应用Unix/Linux时，我们一般想让某个程序在后台运行，于是我们将常会用 & 在程序结尾来让程序自动运行。比如我们要运行mysql在后台： /usr/local/mysql/bin/mysqld_safe –user=mysql &。可是有很多程序并不想mysqld一样，这样我们就需要nohup命令。

[root@manager mha4mysql-manager-0.58]# cd /masterha/
[root@manager masterha]# nohup masterha_manager --conf/etc/masterha/app1.cnf &> /tmp/mha_manager.log &
[2] 99442

检查状态

[root@manager masterha]# masterha_check_status --conf=/etc/masterha/app1.cnf
app1 (pid:99277) is running(0:PING_OK), master:192.168.8.30

故障转移验证

(自动failover) master dead后，MHA当时已经开启，master2（Slave）会自动failover为Master. 验证的方式是先停掉 master1，因为之前的配置文件中，把master2作为了候选人，那么就到 slave 上查看 master 的 IP 是否变为了master2 的 IP

1、停掉 master 在master1上把 mysql 停掉

[root@master1 ~]# systemctl stop mysqld

2、查看 MHA 日志上面的配置文件中指定了日志位置为/masterha/app1/manager.log

[root@manager ~]# cat /masterha/app1/manager.log 
----- Failover Report -----

app1: MySQL Master failover 192.168.8.30(192.168.8.30:3306) to 192.168.8.40(192.168.8.40:3306) succeeded

Master 192.168.8.30(192.168.8.30:3306) is down!

Check MHA Manager logs at manager:/masterha/app1/manager.log for details.

Started automated(non-interactive) failover.
The latest slave 192.168.8.40(192.168.8.40:3306) has all relay logs for recovery.
Selected 192.168.8.40(192.168.8.40:3306) as a new master.
192.168.8.40(192.168.8.40:3306): OK: Applying all logs succeeded.
192.168.8.50(192.168.8.50:3306): This host has the latest relay log events.
Generating relay diff files from the latest slave succeeded.
192.168.8.50(192.168.8.50:3306): OK: Applying all logs succeeded. Slave started, replicating from 192.168.8.40(192.168.8.40:3306)
192.168.8.40(192.168.8.40:3306): Resetting slave info succeeded.
Master failover to 192.168.8.40(192.168.8.40:3306) completed successfully.

从日志信息中可以看到 master failover 已经成功了，并可以看出故障转移的大体流程

3、检查 slave2 的复制登录 slave（192.168.8.50）的Mysql，查看 slave 状态

MySQL-MHA高可用（一）

可以看到 master 的 IP 现在为 192.168.8.40, 已经切换到和192.168.8.40同步了，本来是和192.168.8.30同步的，说明 MHA 已经把master2提升为了新的 master，IO线程和SQL线程也正确运行，MHA搭建成功。

MHA Manager 端日常操作

1、检查是否有下列文件，有则删除。发生主从切换后，MHAmanager服务会自动停掉，且在manager_workdir（/masterha/app1）目录下面生成文件app1.failover.complete，若要启动MHA，必须先确保无此文件。

主从转移后，需要删除下面两个文件。

ll /masterha/app1/app1.failover.complete
ll /masterha/app1/app1.failover.error

2、检查MHA复制检查：（需要把master设置成candicatade的从服务器）

mysql> change master to
    -> master_host='192.168.8.40',
    -> master_port=3306,
    -> master_user='mharep',
    -> master_password='123',
    -> master_log_file='mysql-bin.000007',
    -> master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.03 sec)

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

3、登录manager

[root@manager ~]# masterha_check_repl --conf=/etc/masterha/app1.cnf
#省略部分内容
Thu Apr  6 19:58:27 2023 - [info] Checking replication health on 192.168.8.30..
Thu Apr  6 19:58:27 2023 - [info]  ok.
Thu Apr  6 19:58:27 2023 - [info] Checking replication health on 192.168.8.50..
Thu Apr  6 19:58:27 2023 - [info]  ok.
Thu Apr  6 19:58:27 2023 - [warning] master_ip_failover_script is not defined.
Thu Apr  6 19:58:27 2023 - [warning] shutdown_script is not defined.
Thu Apr  6 19:58:27 2023 - [info] Got exit code 0 (Not master dead).

MySQL Replication Health is OK.

4、停止MHA：

[root@manager ~]# masterha_stop --conf=/etc/masterha/app1.cnf
Stopped app1 successfully.

5、启动MHA：

[root@manager ~]# nohup masterha_manager --conf=/etc/masterha/app1.cnf &>/tmp/mha_manager.log & 
[1] 101196

当有slave 节点宕掉时，默认是启动不了的，加上 --ignore_fail_on_start 即使有节点宕掉也能启动MHA，如下：

nohup masterha_manager --conf=/etc/masterha/app1.cnf --ignore_fail_on_start &>/tmp/mha_manager.log &

6、检查状态：

[root@manager ~]# masterha_check_status --conf=/etc/masterha/app1.cnf 
app1 (pid:101303) is running(0:PING_OK), master:192.168.8.40

7、检查日志：

[root@manager ~]# tail -f /masterha/app1/manager.log

8、主从切换后续工作

重构：重构就是你的主挂了，切换到Candicate master上，Candicate master变成了主，因此重构的一种方案原主库修复成一个新的slave 主库切换后，把原主库修复成新从库，然后重新执行以上5步。

登录master1主机

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.8.40
                  Master_User: mharep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000007
          Read_Master_Log_Pos: 154
               Relay_Log_File: relay-bin.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql-bin.000007
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

启动manager

[root@manager ~]# nohup masterha_manager --conf=/etc/masterha/app1.cnf &> /tmp/mha_manager.log &
[root@manager ~]# masterha_check_status --conf=/etc/masterha/app1.cnf 
app1 (pid:101303) is running(0:PING_OK), master:192.168.8.40

注意：如果正常，会显示"PING_OK"，否则会显示"NOT_RUNNING"，这代表MHA监控没有开启。定期删除中继日志在配置主从复制中，slave上设置了参数relay_log_purge=0，所以slave节点需要定期删除中继日志，建议每个slave节点删除中继日志的时间错开。文章来源地址https://www.toymoban.com/news/detail-418065.html

[root@manager ~]# crontab -e
0 5 * * * /usr/local/bin/purge_relay_logs - -user=root --password=123 --port=3306 --disable_relay_log_purge >> /var/log/purge_relay.log 2>&1

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