第十六章 MHA高可用（续）

一、回顾

1.MHA原理

2.MHA安装

1.安装依赖
2.安装node节点
3.安装manager节点
4.编写配置文件
[root@db03 ~]# vim /service/mha/app1.cnf
[server default]
manager_log=/service/mha/manager
manager_workdir=/service/mha/app1
master_binlog_dir=/usr/local/mysql/data
password=mha
ping_interval=2
repl_password=123
repl_user=rep
ssh_user=root
user=mha

[server1]
hostname=172.16.1.51
port=3306

[server2]
hostname=172.16.1.52
port=3306

[server3]
hostname=172.16.1.53
port=3306
5.创建工作目录
6.创建MHA管理数据库的用户
7.所有机器之间免密连接
8.检测主从状态和ssh免密连接状态
9.启动MHA
[root@db03 ~]# nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &
10.关闭主库测试

二、恢复MHA故障

1.手动修复

1）修复挂掉的数据库

[root@db01 ~]# systemctl start mysqld

2）找到主从语句

[root@db03 ~]# grep 'CHANGE MASTER TO' /service/mha/manager 
Mon Nov  9 20:14:17 2020 - [info]  All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='172.16.1.52', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000007', MASTER_LOG_POS=120, MASTER_USER='rep', MASTER_PASSWORD='xxx';

3）修复的数据库执行change语句

#修改一下语句中的密码，执行即可
mysql> CHANGE MASTER TO MASTER_HOST='172.16.1.52', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000007', MASTER_LOG_POS=120, MASTER_USER='rep', MASTER_PASSWORD='123';
Query OK, 0 rows affected, 2 warnings (0.01 sec)

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

4）查看主从状态

mysql> show slave statusG
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.16.1.52
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000007
          Read_Master_Log_Pos: 211
               Relay_Log_File: db01-relay-bin.000002
                Relay_Log_Pos: 374
        Relay_Master_Log_File: mysql-bin.000007
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

5）修复MHA配置

[root@db03 ~]# vim /service/mha/app1.cnf
[server default]
manager_log=/service/mha/manager
manager_workdir=/service/mha/app1
master_binlog_dir=/usr/local/mysql/data
password=mha
ping_interval=2
repl_password=123
repl_user=rep
ssh_user=root
user=mha

[server1]
hostname=172.16.1.51
port=3306

[server2]
hostname=172.16.1.52
port=3306

[server3]
hostname=172.16.1.53
port=3306

6）重新启动MHA

[root@db03 ~]# nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &

2.脚本修复

1）创建脚本目录

[root@db02 ~]# mkdir /scripts

2）写脚本

[root@db02 ~]# vim /scripts/start_mha.sh
[root@db02 ~]# cat /scripts/start_mha.sh 
#!/bin/bash
#1.启动数据库
systemctl start mysqld
#2.获取配置主从语句
change=`ssh 172.16.1.53 "grep 'CHANGE MASTER TO' /service/mha/manager | tail -1 | sed 's#xxx#123#g'" | awk -F: '{print $4}'`
#3.执行主从语句并启动线程
mysql -e "$change; start slave"
#4.替换MHA配置文件
ssh 172.16.1.53 "cp /service/mha/app1.bak /service/mha/app1.cnf"
#5.启动MHA
ssh 172.16.1.53 "nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &"

3）加上判断

[root@db02 ~]# cat /scripts/start_mha.sh 
#!/bin/bash
#1.mysql进程数赋值
mysqlpid=`ps -ef | grep [m]ysql | wc -l`
#2.判断MySQL是否假死，如果假死杀掉重启，如果关闭则启动
if [ $mysqlpid -eq 0 ];then
    systemctl start mysqld
else
    pkill mysqld
    systemctl start mysqld
fi
#3.获取配置主从语句
change=`ssh 172.16.1.53 "grep 'CHANGE MASTER TO' /service/mha/manager | tail -1 | sed 's#xxx#123#g'" | awk -F: '{print $4}'`
#4.执行主从语句并启动线程
mysql -e "$change; start slave"
#5.替换MHA配置文件
ssh 172.16.1.53 "cp /service/mha/app1.bak /service/mha/app1.cnf"
#6.启动MHA
ssh 172.16.1.53 "nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &"

三、MHA切换机制

1.MHA切换机制

1.读取配置中指定优先级的配置
	candidate_master=1
	check_repl_delay=0
2.如果没有配置优先级，读取数据最新的
3.如果数据量相同，读取主机标签，值越小越优先

2.测试标签优先级

#1.停掉MHA
[root@db03 ~]# masterha_stop --conf=/service/mha/app1.cnf

#2.配置MHA
[root@db03 ~]# vim /service/mha/app1.cnf
... ...
[server1]
hostname=172.16.1.51
port=3306

[server2]
hostname=172.16.1.52
port=3306

[server3]
hostname=172.16.1.53
port=3306

#3.重启MHA
[root@db03 ~]# nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &

#4.停掉主库
[root@db02 ~]# systemctl stop mysqld

#5.查看主从
[root@db01 ~]# mysql
mysql> show slave statusG
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.16.1.53
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000008
          Read_Master_Log_Pos: 120
               Relay_Log_File: db01-relay-bin.000002
                Relay_Log_Pos: 283
        Relay_Master_Log_File: mysql-bin.000008
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

3.指定优先级测试

#配置优先级
[root@db03 ~]# vim /service/mha/app1.cnf
... ...
[server3]
candidate_master=1
check_repl_delay=0
hostname=172.16.1.53
port=3306

#重启MHA
[root@db03 ~]# nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &

#停止主库
[root@db01 ~]# systemctl stop mysqld

4.测试数据最新的优先级

1）去掉优先级配置

[root@db03 ~]# masterha_stop --conf=/service/mha/app1.cnf
#去掉优先级配置
#candidate_master=1
#check_repl_delay=0

#重启mha
[root@db03 ~]# nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &

2）主库建库建表

mysql> create database youxianji;
Query OK, 1 row affected (0.00 sec)

mysql> use youxianji
Database changed

mysql> create table linux10(id int not null primary key auto_increment,name varchar(10));
Query OK, 0 rows affected (0.02 sec)

3）编写脚本插入数据

[root@db03 ~]# mkdir /scripts
[root@db03 ~]# vim /scripts/insert.sh
#!/bin/bash
while true;do
    mysql -e "use youxianji;insert linux10(name) values('qiudao')"
done

4）停掉db01的IO线程

[root@db01 ~]# mysql
mysql> stop slave io_thread;

5）停掉主库

[root@db03 ~]# systemctl stop mysqld

6）查看从库状态

[root@db01 ~]# mysql
mysql> show slave statusG
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.16.1.52
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000010
          Read_Master_Log_Pos: 1524539
               Relay_Log_File: db01-relay-bin.000002
                Relay_Log_Pos: 283
        Relay_Master_Log_File: mysql-bin.000010
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

四、主库断电，binlog如何保存

1.配置binlog-server

[root@db03 ~]# cat /service/mha/app1.cnf 
... ...
[server1]
hostname=172.16.1.51
port=3306

[server2]
hostname=172.16.1.52
port=3306

[server3]
hostname=172.16.1.53
port=3306

[binlog1]
no_master=1
hostname=172.16.1.53
master_binlog_dir=/data/mysql/binlog/

2.创建存放binlog的目录

[root@db03 ~]# mkdir /data/mysql/binlog/ -p

3.手动执行实时备份binlog的命令

[root@db03 ~]# cd /data/mysql/binlog/

#备份binlog命令
[root@db03 /data/mysql/binlog]# mysqlbinlog -R --host=172.16.1.51 --user=mha --password=mha --raw --stop-never mysql-bin.000001 &

#参数详解
-R					#从远端服务器获取binlog
--host=172.16.1.51	 #指定远端的主机
--user=mha			#数据库mha用户
--password=mha		#数据库mha用户的密码
--raw				#binlog获取时的一种格式
--stop-never mysql-bin.000001		#从mysql-bin.000001开始不停的备份binlog

4.启动mha

#启动mha
nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &

5.加入恢复MHA进程脚本

[root@db02 ~]# cat /scripts/start_mha.sh
#!/bin/bash

#1.mysql进程数赋值
mysqlpid=`ps -ef | grep [m]ysql | wc -l`

#2.判断MySQL是否假死，如果假死杀掉重启，如果关闭则启动
if [ $mysqlpid -eq 0 ];then
    systemctl start mysqld
else
    pkill mysqld
    systemctl start mysqld
fi

#3.获取配置主从语句
change=`ssh 172.16.1.53 "grep 'CHANGE MASTER TO' /service/mha/manager | tail -1 | sed 's#xxx#123#g'" | awk -F: '{print $4}'`

#4.执行主从语句并启动线程
mysql -e "$change; start slave"

#5.获取主节点IP
master_ip=`ssh 172.16.1.53 "mysql -e 'show slave statusG'" | awk 'NR==3 {print $2}'`

#6.启动实时获取binlog进程
ssh 172.16.1.53 "cd /data/mysql/binlog && mysqlbinlog -R --host=$master_ip --user=mha --password=mha --raw --stop-never mysql-bin.000001 &> /dev/null &"

#7.替换MHA配置文件
ssh 172.16.1.53 "cp /service/mha/app1.bak /service/mha/app1.cnf"

#8.启动MHA
ssh 172.16.1.53 "nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &"

6.拆成两个脚本

[root@db01 ~]# cat /scripts/start_mha.sh 
#!/bin/bash

#1.mysql进程数赋值
mysqlpid=`ps -ef | grep [m]ysql | wc -l`

#2.判断MySQL是否假死，如果假死杀掉重启，如果关闭则启动
if [ $mysqlpid -eq 0 ];then
    systemctl start mysqld
else
    pkill mysqld
    systemctl start mysqld
fi

sleep 3

#3.获取配置主从语句
change=`ssh 172.16.1.53 "grep 'CHANGE MASTER TO' /service/mha/manager | tail -1 | sed 's#xxx#123#g'" | awk -F: '{print $4}'`

#4.执行主从语句并启动线程
mysql -e "$change; start slave" 2>&1

#5.远程执行启动mha脚本
ssh 172.16.1.53 "sh /scripts/recovery.sh"

[root@db03 ~]# cat /scripts/recovery.sh 
#1.获取主节点IP
master_ip=`mysql -e 'show slave statusG' | awk 'NR==3 {print $2}'`

#2.进入保存binlog目录
cd /data/mysql/binlog 

#3.启动实时获取binlog进程
mysqlbinlog -R --host=$master_ip --user=mha --password=mha --raw --stop-never mysql-bin.000001&> /dev/null &

#4.替换MHA配置文件
/usr/bin/cp /service/mha/app1.bak /service/mha/app1.cnf

#8.启动MHA
nohup masterha_manager --conf=/service/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /service/mha/app1/manager.log 2>&1 &


change master to 
master_host='172.16.1.51',
master_port=3306,
master_user='rep',
master_password='123',
master_log_file='mysql-bin.000001',
master_log_pos=120;