一、案例前置知识
1、MHA概述
·一套优秀的MySQL高可用环境下故障切换和主从复制的软件
·MySQL故障过程中，MHA能做到0-30秒内自动完成故障切换
2、MHA的组成
·MHA Manager（管理节点）
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（数据节点）
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。
3、MHA特点
·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不丢失
·使用半同步复制，可以大大降低数据丢失的风险
·目前MHA支持一主多从架构，最少三台服务，即一主两从
4、MHA缺点
·需要编写脚本或利用第三方工具来实现vip的配置
·MHA启动后只会对数据库进行监控，需要基于ssh免认证配置，存在一定的安全隐患
·没有提供从服务器的读负载均很的功能。
二、案例拓扑图
三、案例部署
1、部署思路
（1）、MHA架构
①数据库安装
②一主两从
③MHA搭建
2、故障模拟
①主库失效
②备选主库成为主库
③从库2将备选主库指向为主库
3、故障修复
①坏库修复，启动
②在修复好的库上建立新主从关系
③修改manager配置文件，添加修好的库的记录
④重启mha
主服务器：mysql-server 20.0.0.10，从1服务器：mysql-slave1 20.0.0.20，从2服务器：mysql-slave2 20.0.0.30，mha:20.0.0.40
2、在三台 MySQL 节点上分别安装数据库
MySQL 版本请使用 5.6.36，cmake 版本请使用 2.8.6。安装过程如下。
yum -y install ncurses-devel gcc-c++ perl-Module-Install
tar zxvf cmake-2.8.6.tar.gz
cd cmake-2.8.6
./configure
gmake && gmake install
cd
tar zxvf mysql-5.6.36.tar.gz
cd mysql-5.6.36
cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql -DDEFAULT_CHARSET=utf8 -DDEFAULT_COLLATION=utf8_general_ci -DWITH_EXTRA_CHARSETS=all -DSYSCONFDIR=/etc
make && make install
cp support-files/my-default.cnf /etc/my.cnf
cp support-files/mysql.server /etc/rc.d/init.d/mysqld
chmod +x /etc/rc.d/init.d/mysqld
chkconfig --add mysqld
echo "PATH=$PATH:/usr/local/mysql/bin" >> /etc/profile
source /etc/profile
groupadd mysql
useradd -M -s /sbin/nologin mysql -g mysql
chown -R mysql.mysql /usr/local/mysql
mkdir -p /data/mysql
/usr/local/mysql/scripts/mysql_install_db --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --user=mysql
echo '
[client]
port = 3306
socket = /usr/local/mysql/mysql.sock
port = 3306
socket = /usr/local/mysql/mysql.sock
user = mysql
basedir = /usr/local/mysql
datadir = /usr/local/mysql/data
port = 3306
pid-file = /usr/local/mysql/mysqld.pid
socket = /usr/local/mysql/mysql.sock
server-id = 1
log_bin = master-bin
log-slave-updates = true
ln -s /usr/local/mysql/bin/mysql /usr/sbin/
ln -s /usr/local/mysql/bin/mysqlbinlog /usr/sbin/
systemctl start mysqld
netstat -anpt | grep 3306
yum -y install ncurses-devel gcc-c++ perl-Module-Install
tar zxvf cmake-2.8.6.tar.gz
cd cmake-2.8.6
./configure
gmake && gmake install
cd
tar zxvf mysql-5.6.36.tar.gz
cd mysql-5.6.36
cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql -DDEFAULT_CHARSET=utf8 -DDEFAULT_COLLATION=utf8_general_ci -DWITH_EXTRA_CHARSETS=all -DSYSCONFDIR=/etc
make && make install
cp support-files/my-default.cnf /etc/my.cnf
cp support-files/mysql.server /etc/rc.d/init.d/mysqld
chmod +x /etc/rc.d/init.d/mysqld
chkconfig --add mysqld
echo "PATH=$PATH:/usr/local/mysql/bin" >> /etc/profile
source /etc/profile
groupadd mysql
useradd -M -s /sbin/nologin mysql -g mysql
chown -R mysql.mysql /usr/local/mysql
mkdir -p /data/mysql
/usr/local/mysql/scripts/mysql_install_db --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --user=mysql
echo '
[client]
port = 3306
socket = /usr/local/mysql/mysql.sock
port = 3306
socket = /usr/local/mysql/mysql.sock
user = mysql
basedir = /usr/local/mysql
datadir = /usr/local/mysql/data
port = 3306
pid-file = /usr/local/mysql/mysqld.pid
socket = /usr/local/mysql/mysql.sock
server-id = 2
log_bin = master-bin
relay-log = relay-log-bin
relay-log-index = slave-relay-bin.index
ln -s /usr/local/mysql/bin/mysql /usr/sbin/
ln -s /usr/local/mysql/bin/mysqlbinlog /usr/sbin/
systemctl start mysqld
netstat -anpt | grep 3306
yum -y install ncurses-devel gcc-c++ perl-Module-Install
tar zxvf cmake-2.8.6.tar.gz
cd cmake-2.8.6
./configure
gmake && gmake install
cd
tar zxvf mysql-5.6.36.tar.gz
cd mysql-5.6.36
cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql -DDEFAULT_CHARSET=utf8 -DDEFAULT_COLLATION=utf8_general_ci -DWITH_EXTRA_CHARSETS=all -DSYSCONFDIR=/etc
make && make install
cp support-files/my-default.cnf /etc/my.cnf
cp support-files/mysql.server /etc/rc.d/init.d/mysqld
chmod +x /etc/rc.d/init.d/mysqld
chkconfig --add mysqld
echo "PATH=$PATH:/usr/local/mysql/bin" >> /etc/profile
source /etc/profile
groupadd mysql
useradd -M -s /sbin/nologin mysql -g mysql
chown -R mysql.mysql /usr/local/mysql
mkdir -p /data/mysql
/usr/local/mysql/scripts/mysql_install_db --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --user=mysql
echo '
[client]
port = 3306
socket = /usr/local/mysql/mysql.sock
port = 3306
socket = /usr/local/mysql/mysql.sock
user = mysql
basedir = /usr/local/mysql
datadir = /usr/local/mysql/data
port = 3306
pid-file = /usr/local/mysql/mysqld.pid
socket = /usr/local/mysql/mysql.sock
server-id = 3
relay-log = relay-log-bin
relay-log-index = slave-relay-bin.index
ln -s /usr/local/mysql/bin/mysql /usr/sbin/
ln -s /usr/local/mysql/bin/mysqlbinlog /usr/sbin/
systemctl start mysqld
netstat -anpt | grep 3306
3、配置 MySQL一主两从
（1）、MySQL 主从配置相对比较简单，需要注意的是授权。步骤如下：在所有数据库节点上授权两个用户，一个是从库同步使用，另外一个是 manager 使用。
mysql> grant replication slave on *.* to 'myslave'@'20.0.0.%' identified by '123';
mysql> grant all privileges on *.* to 'mha'@'20.0.0.%' identified by 'manager';
mysql> flush privileges;
（2）、在主服务器上查看二进制文件和同步点
mysql> show master status;
+-------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------+----------+--------------+------------------+-------------------+
| master-bin.000001 | 608 | | | |
+-------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
（3）、接下来在从1 和 从2 分别执行同步,查看 IO 和 SQL 线程都是 yes 代表同步是否正常
mysql> change master to master_host='20.0.0.10',master_user='myslave',master_password='123',master_log_file='master-bin.000001',master_log_pos=608;
mysql> start slave;
mysql> show slave statusG;
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
1 I/O线程显示为NO: 主库与从库网络不通、主库未授权给从库
2 SQL线程显示为NO：从库日志和位置点与主不同步
3 若从库查看连接主库I/0线程状态为conneting，一直是这个状态，考虑双方的防火墙是否开启。
（4）、必须设置两个从库为只读模式
mysql> set global read_only=1;
（5）、在主库插入两条数据，测试是否同步
mysql> create database test_lixing;
mysql> use test_lixing;
mysql> create table test(id int);
mysql> insert into test(id) values (1);
mysql> select * from test;
（6）、在两个从库分别查询如下所示说明主从同步正常
从1
mysql> select * from test_lixing.test;
+------+
| id |
+------+
| 1 |
+------+
1 row in set (0.00 sec)
从2
mysql> select * from test_lixing.test;
+------+
| id |
+------+
| 1 |
+------+
1 row in set (0.00 sec)
4、安装MHA软件
（1）、在所有服务器上都安装 MHA 依赖的环境，每个服务器上都需要两个源（epel.repo和CentOS7-Base-163.repo）,将这两个源放入/etc/yum.repos.d的目录下，在主服务器上操作演示安装
yum install epel-release --nogpgcheck
yum install -y perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-ExtUtils-CBuilder perl-ExtUtils-MakeMaker perl-CPAN
（2）、在所有服务器上必须先安装 node 组件，最后在 MHA-manager 节点上安装 manager 组件，因为 manager 依赖 node 组件
tar zxvf mha4mysql-node-0.57.tar.gz
cd mha4mysql-node-0.57
perl Makefile.PL
make && make install
（3）、在mha-manager 服务器上安装 manager 组件
cd mha4mysql-manager-0.57
perl Makefile.PL
*** Checking for Perl dependencies...
[Core Features]
- DBI ...loaded. (1.627)
- DBD::mysql ...loaded. (4.023)
- Time::HiRes ...loaded. (1.9725)
- Config::Tiny ...loaded. (2.14)
- Log::Dispatch ...loaded. (2.41)
- Parallel::ForkManager ...loaded. (1.18)
- MHA::NodeConst ...loaded. (0.57)
*** Module::AutoInstall configuration finished.
Checking if your kit is complete...
Looks good
Writing Makefile for mha4mysql::manager
manager 安装后在/usr/local/bin 下面会生成几个工具，主要包括以下几个：
masterha_check_ssh 检查 MHA 的 SSH 配置状况
masterha_check_repl 检查 MySQL 复制状况
masterha_manger 启动 manager的脚本
masterha_check_status 检测当前 MHA 运行状态
masterha_master_monitor 检测 master 是否宕机
masterha_master_switch 控制故障转移（自动或者手动）
masterha_conf_host 添加或删除配置的 server 信息
masterha_stop 关闭manager
node 安装后也会在/usr/local/bin 下面会生成几个脚本（这些工具通常由 MHA-Manager 的脚本触发，无需人为操作）主要如下：
save_binary_logs 保存和复制 master 的二进制日志
apply_diff_relay_logs 识别差异的中继日志事件并将其差异的事件应用于其他的 slave
filter_mysqlbinlog 去除不必要的 ROLLBACK 事件（MHA 已不再使用这个工具）
purge_relay_logs 清除中继日志（不会阻塞 SQL 线程）
5、配置无密码认证
（1）、在 manager服务器 上配置到所有节点的无密码认证
ssh-keygen -t rsa #一路按回车键
ssh-copy-id 20.0.0.10 #先输入yes，再输入20.0.0.10服务器的密码
ssh-copy-id 20.0.0.20
ssh-copy-id 20.0.0.30
验证
ssh root@20.0.0.10
ssh root@20.0.0.20
ssh root@20.0.0.30
（2）、在主服务器上配置到数据库节点的无密码认证
ssh-keygen -t rsa
ssh-copy-id 20.0.0.20
ssh-copy-id 20.0.0.30
验证
ssh root@20.0.0.20
ssh root@20.0.0.30
（3）、在从1服务器上配置到数据库节点的无密码认证
ssh-keygen -t rsa
ssh-copy-id 20.0.0.10
ssh-copy-id 20.0.0.30
验证
ssh root@20.0.0.10
ssh root@20.0.0.30
（4）、在从2服务器上配置到数据库节点的无密码认证
ssh-keygen -t rsa
ssh-copy-id 20.0.0.10
ssh-copy-id 20.0.0.20
验证
ssh root@20.0.0.10
ssh root@20.0.0.20
6、配置 MHA
（1）、在 manager 节点上复制相关脚本到/usr/local/bin 目录,复制上述的自动切换时 VIP 管理的脚本到/usr/local/bin 目录，这里使用脚本管理 VIP
ll /usr/local/bin/scripts/
cp /usr/local/bin/scripts/master_ip_failover /usr/local/bin
vi /usr/local/bin/master_ip_failover
删除文件里的所有内容，复制下面的内容
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';
$command, $ssh_user, $orig_master_host, $orig_master_ip,
$orig_master_port, $new_master_host, $new_master_ip, $new_master_port
);
#############################添加内容部分#########################################
my $vip = '20.0.0.200';
my $brdc = '20.0.0.255';
my $ifdev = 'ens33';
my $key = '1';
my $ssh_start_vip = "/sbin/ifconfig ens33:$key $vip";
my $ssh_stop_vip = "/sbin/ifconfig ens33:$key down";
my $exit_code = 0;
#my $ssh_start_vip = "/usr/sbin/ip addr add $vip/24 brd $brdc dev $ifdev label $ifdev:$key;/usr/sbin/arping -q -A -c 1 -I $ifdev $vip;iptables -F;";
#my $ssh_stop_vip = "/usr/sbin/ip addr del $vip/24 dev $ifdev label $ifdev:$key";
##################################################################################
GetOptions(
'command=s' => $command,
'ssh_user=s' => $ssh_user,
'orig_master_host=s' => $orig_master_host,
'orig_master_ip=s' => $orig_master_ip,
'orig_master_port=i' => $orig_master_port,
'new_master_host=s' => $new_master_host,
'new_master_ip=s' => $new_master_ip,
'new_master_port=i' => $new_master_port,
);
eval {
print "Disabling the VIP on old master: $orig_master_host ";
&stop_vip();
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@ ";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {
eval {
print "Enabling the VIP - $vip on the new master - $new_master_host ";
&start_vip();
$exit_code = 0;
};
if ($@) {
warn $@;
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
print "Checking the Status of the script.. OK ";
exit 0;
}
else {
&usage();
exit 1;
}
}
sub start_vip() {
`ssh $ssh_user@$new_master_host " $ssh_start_vip "`;
}
# A simple system call that disable the VIP on the old_master
sub stop_vip() {
`ssh $ssh_user@$orig_master_host " $ssh_stop_vip "`;
}
"Usage: master_ip_failover --command=start|stop|stopssh|status --orig_master_host=host --orig_master_ip=ip --orig_master_port=port --new_master_host=host --new_master_ip=ip --new_master_port=port ";
}
拷贝后会有四个执行文件，文件的含义如下：
master_ip_failover #自动切换时 VIP 管理的脚本
master_ip_online_change #在线切换时 vip 的管理
power_manager #故障发生后关闭主机的脚本
send_report #因故障切换后发送报警的脚本
（2）、创建 MHA 软件目录并拷贝配置文件
1 mkdir /etc/masterha
2 cp mha4mysql-manager-0.57/samples/conf/app1.cnf /etc/masterha/
3 vim /etc/masterha/app1.cnf
4 [server default]
5 manager_workdir=/var/log/masterha/app1
6 manager_log=/var/log/masterha/app1/manager.log
7 master_binlog_dir=/usr/local/mysql/data
8 master_ip_failover_script= /usr/local/bin/master_ip_failover
9 master_ip_online_change_script= /usr/local/bin/master_ip_online_change10 password=manager
11 user=mha
12 ping_interval=1
13 remote_workdir=/tmp
14 repl_password=123
15 repl_user=myslave
16 secondary_check_script= /usr/local/bin/masterha_secondary_check -s 20.0.0.20 -s 20.0.0.30
17 shutdown_script=""
18 ssh_user=root
19 [server1]
20 hostname=20.0.0.10
21 port=3306
22 [server2]
23 hostname=20.0.0.20
24 port=3306
25 candidate_master=1
26 check_repl_delay=0
27 [server3]
28 hostname=20.0.0.30
29 port=3306
（3）、测试 ssh 无密码认证，如果正常最后会输出 successfully，如下所示
masterha_check_ssh -conf=/etc/masterha/app1.cnf
......
Wed Oct 28 00:07:09 2020 - [debug] Connecting via SSH from root@20.0.0.30(20.0.0.30:22) to root@20.0.0.20(20.0.0.20:22)..
Wed Oct 28 00:07:10 2020 - [debug] ok.
Wed Oct 28 00:07:10 2020 - [debug]
Wed Oct 28 00:07:08 2020 - [debug] Connecting via SSH from root@20.0.0.20(20.0.0.20:22) to root@20.0.0.10(20.0.0.10:22)..
Wed Oct 28 00:07:09 2020 - [debug] ok.
Wed Oct 28 00:07:09 2020 - [debug] Connecting via SSH from root@20.0.0.20(20.0.0.20:22) to root@20.0.0.30(20.0.0.30:22)..
Wed Oct 28 00:07:09 2020 - [debug] ok.
Wed Oct 28 00:07:10 2020 - [info] All SSH connection tests passed successfully.
（4）、测试 MySQL 主从连接情况，最后出现 MySQL Replication Health is OK 字样说明正常
......
IN SCRIPT TEST====/sbin/ifconfig ens33:1 down==/sbin/ifconfig ens33:1 20.0.0.200===
Wed Oct 28 09:25:28 2020 - [info] OK.
Wed Oct 28 09:25:28 2020 - [warning] shutdown_script is not defined.
Wed Oct 28 09:25:28 2020 - [info] Got exit code 0 (Not master dead).
（5）、启动 MHA
nohup masterha_manager --conf=/etc/masterha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /var/log/masterha/app1/manager.log 2>&1 &
（6）、查看 MHA 状态，可以看到当前的 master 是主服务器节点
masterha_check_status --conf=/etc/masterha/app1.cnf
app1 (pid:24405) is running(0:PING_OK), master:20.0.0.10
（7）、查看 MHA 日志，也以看到当前的 master 是 20.0.0.10
cat /var/log/masterha/app1/manager.log
......
Wed Oct 28 09:27:04 2020 - [info] Replicating from 20.0.0.10(20.0.0.10:3306)
Wed Oct 28 09:27:04 2020 - [info] Current Alive Master: 20.0.0.10(20.0.0.10:3306)
Wed Oct 28 09:27:04 2020 - [info] Checking slave configurations..
Wed Oct 28 09:27:04 2020 - [warning] relay_log_purge=0 is not set on slave 20.0.0.20(20.0.0.20:3306).
Wed Oct 28 09:27:04 2020 - [warning] relay_log_purge=0 is not set on slave 20.0.0.30(20.0.0.30:3306).
Wed Oct 28 09:27:04 2020 - [warning] log-bin is not set on slave 20.0.0.30(20.0.0.30:3306). This host cannot be a master.
......
（8）、第一次配置vip的时候，需要在主服务器上创建虚拟IP地址
ifconfig ens33:1 20.0.0.200/24
ifconfig
四、故障测试
1、关闭主服务器的mysql服务
pkill mysqld
2、查看从1服务器的虚拟IP地址有没有转移过来，从2上查看主服务器是不是从1
ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 20.0.0.20 netmask 255.255.255.0 broadcast 20.0.0.255
inet6 fe80::a140:18a2:d866:8f33 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:42:10:0a txqueuelen 1000 (Ethernet)
RX packets 1315993 bytes 1324408060 (1.2 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 795190 bytes 69519345 (66.2 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
inet 20.0.0.200 netmask 255.0.0.0 broadcast 20.255.255.255
ether 00:0c:29:42:10:0a txqueuelen 1000 (Ethernet)
mysql
mysql> show slave status G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 20.0.0.20
Master_User: myslave
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: master-bin.000003
Read_Master_Log_Pos: 120
Relay_Log_File: relay-log-bin.000002
Relay_Log_Pos: 284
Relay_Master_Log_File: master-bin.000003
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
......
3、重新开启manager服务器
（1）、主服务器开启mysql服务
systemctl restart mysqld
（2）、查看从1服务器查看二进制文件和同步点
mysql> show master status;
+-------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------+----------+--------------+------------------+-------------------+
| master-bin.000003 | 120 | | | |
+-------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
（3）、在主服务器上执行同步,查看 IO 和 SQL 线程都是 yes 代表同步是否正常
mysql> change master to
master_host='20.0.0.20',master_user='myslave',master_password='123',master_log_file='master-bin.000003',master_log_pos=120;
mysql> start slave;
mysql> show slave status G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 20.0.0.20
Master_User: myslave
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: master-bin.000003
Read_Master_Log_Pos: 120
Relay_Log_File: mysqld-relay-bin.000002
Relay_Log_Pos: 284
Relay_Master_Log_File: master-bin.000003
Slave_IO_Running: Yes
Slave_SQL_Running: Yes18 ......
（4）、在从1上创建，主服务器和从2上查看
mysql> create database aa;
mysql> use aa;
mysql> create table test(id int(3));
mysql> insert into test values(1);
mysql> select * from test;
+------+
| id |
+------+
| 1 |
+------+
mysql> use aa;
mysql> select * from test;
+------+
| id |
+------+
| 1 |
+------+
mysql> use aa;
mysql> select * from test;
+------+
| id |
+------+
| 1 |
+------+
（5）、在manager服务器上修改配置文件(再把这个记录添加进去，因为它检测掉失效时候会自动消失)
vi /etc/masterha/app1.cnf
......
[server1]
hostname=192.168.8.134
port=3306
......
（6）、在manager服务器上启动manager
masterha_check_ssh -conf=/etc/masterha/app1.cnf
masterha_check_repl -conf=/etc/masterha/app1.cnf
nohup masterha_manager --conf=/etc/masterha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /var/log/masterha/app1/manager.log 2>&1 &
masterha_check_status --conf=/etc/masterha/app1.cnf