MySQL MHA: A master-slave replication solution with master high availability

outline

• foreword

• Architecture of MHA

• Environment deployment

• Experimental procedure

• Summarize

foreword

In the last article, we implemented MySQLmaster-slave replication, but as we said before, there are many problems with master-slave replication . In this article, we will introduce how to use MHAit to achieve MySQLhigh availability of replicated clusters.

Architecture of MHA

MHA  (Master HA) realizes the high availability of MySQL master-slave replication master node  , which mainly realizes

• Automated master monitoring and  failover

• Interactive (manual) Master Failover  Manual failover

• Non-interactive master  failover

• Online switching master to a different  host

Project address Google Code

The MHA service has two roles to complete the corresponding functions

• MHA Manager (management node): usually deployed on a single host alone to manage multiple Master/Slave clusters, each cluster is usually called an Application 

• MHA Slave (data node): usually deployed on a single MySQL server, with monitoring and scripts with parsing and cleaning log functions to speed up failover

    

• When the MySQL master node fails , follow the steps below to transfer 

    

Components of the MHA

Components of the Manager Node

• masterha_check_ssh : MHA-dependent SSH environment detection tool

• masterha_repl : MySQL replication environment detection tool

• masterha_manager : MHA service main program

• masterha_check_status : MySQL master node availability detection tool

• masterha_conf_host : add or remove configured nodes

• masterha_stop : Tool to stop MHA service

Components of a Node node

• save_binary_logs : save and copy master's binary logs

• apply_diff_relay_logs : Relay logs identifying differences to apply to other slaves

• filter_mysqbinlog : remove unnecessary ROLLBACK events (MHA has removed this tool)

• purge_relay_logs : purge relay logs (will not block SQL thread)

custom extension

• secondary_check_script : Check master availability through multiple network routes

• master_ip_failover_script : update the masterip used by the application

• shutdown_script : forcibly shut down the master node

• report_script : send report

• init_conf_load_script : load initial configuration parameters

• master_ip_online_change_script : update the ip address of the master node

Environment deployment

lab environment

node	IP	function
node1	172.16.1.2	Master Node
node2	172.16.1.3	Slave Node/Master Node
node3	172.16.1.4	Slave Node
node4	172.16.1.5	Manager Node

Experimental topology

When the master node goes down, the node2 node automatically replaces it as the master node

Software version

MHA download address

software	Version
MySQL	5.1
MHA_Manager	0.56
MHA_Node	0.54

Experimental procedure

Install and configure mysql

[root@node1 ~]# yum install mysql-server -y
[root@node2 ~]# yum install mysql-server -y
[root@node3 ~]# yum install mysql-server -y
[root@node4 ~]# yum install mysql-server -y

mysql_master_node configuration file

I will not explain too much configuration here, if you are interested, you can read my last article

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
innodb_file_per_table = 1
log-bin=master-log
log-bin-index=1
server_id=1
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

master_slave_node configuration file

We only show the configuration file of one node here

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
innodb_file_per_table = 1
log-bin = master-log
log-bin-index = 1
relay-log = relay-log
read_only = 1
server_id=2    #每个从服务器要使用不同的
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

Configure master-slave

MySQL Master node configuration

We need to create a user with super permission to manage the MHA_Manager to control each node

mysql> SHOW MASTER STATUS;  #一定要在创建用户前查看并记下POS数值
+-------------------+----------+--------------+------------------+
| File              | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+-------------------+----------+--------------+------------------+
| master-log.000003 |      106 |              |                  |
+-------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

mysql> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'rpuser'@'%' IDENTIFIED BY 'passwd';
Query OK, 0 rows affected (0.00 sec)

ENTFIED BY 'passwd'' at line 1mysql> GRANT ALL ON *.* TO 'mhauser'@'%' IDENTIFIED BY 'passwd';
Query OK, 0 rows affected (0.00 sec)

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

MySQL Slave Node Configuration

mysql> CHANGE MASTER TO 
    -> MASTER_HOST='172.16.1.2',
    -> MASTER_USER='rpuser',
    -> MASTER_PASSWORD='passwd',
    -> MASTER_LOG_FILE='master-log.000003',
    -> MASTER_LOG_POS=106;
Query OK, 0 rows affected (0.03 sec)

mysql> START SLAVE;    #启动slave
Query OK, 0 rows affected (0.00 sec)

mysql> SHOW SLAVE STATUS\G;  #查看slave-IO和slave-SQL是否为YES
    Master_Host: 172.16.1.2
    Master_User: rpuser
    Master_Port: 3306
    Connect_Retry: 60
    Master_Log_File: master-log.000003
    Read_Master_Log_Pos: 476
    Relay_Log_File: relay-log.000002
    Relay_Log_Pos: 622
    Relay_Master_Log_File: master-log.000003
    Slave_IO_Running: Yes
    Slave_SQL_Running: Yes

Configure MHA

Configuration prerequisites

We need to configure each host to be able to trust each other

Mutual trust configuration for each host

Here we use a very simple method to achieve

生成密钥后, 复制到各节点主机
[root@node4 ~]# ssh-keygen -P '' -t rsa -f /root/.ssh/id_rsa #在node4生成密钥
[root@node4 ~]# cat /root/.ssh/id_rsa.pub > /root/.ssh/authorized_keys 
[root@node4 ~]# scp /root/.ssh/{id_rsa,authorized_keys} node1.anyisalin.com:/root/.ssh/
[root@node4 ~]# scp /root/.ssh/{id_rsa,authorized_keys} node2.anyisalin.com:/root/.ssh/
[root@node4 ~]# scp /root/.ssh/{id_rsa,authorized_keys} node3.anyisalin.com:/root/.ssh/

Install MHA

[root@node4 ~]# yum localinstall mha4mysql-manager-0.56-0.el6.noarch.rpm mha4mysql-node-0.54-0.el6.noarch.rpm  #在manager节点上安装这两个包

#在各个node节点安装mha_node
[root@node2 ~]# yum localinstall mha4mysql-node-0.54-0.el6.noarch.rpm
[root@node3 ~]# yum localinstall mha4mysql-node-0.54-0.el6.noarch.rpm
[root@node4 ~]# yum localinstall mha4mysql-node-0.54-0.el6.noarch.rpm

Create configuration file

[root@node4 ~]# vim /etc/mha.cnf

    [server default]
    user=mhauser
    password=passwd
    manager_workdir=/data/masterha/app1    
    manager_log=/data/masterha/app1/manager.log
    remote_workdir=/data/masterha/app1
    ssh_user=root
    repl_user=rpuser
    repl_password=passwd
    ping_interval=1

    [server1]
    hostname=172.16.1.2
    candidate_master=1

    [server2]
    hostname=172.16.1.3
    candidate_master=1

    [server3]
    hostname=172.16.1.4

Check the environment

Use the built-in detection tool to check the environment before starting Masterha

[root@node4 ~]# masterha_check_ssh --conf=/etc/mha.cnf  #检查ssh, --conf指定配置文件

#最后出现以下字段代表成功
Thu Apr 28 19:02:05 2016 - [info] All SSH connection tests passed successfully.

[root@node4 ~]# masterha_check_repl --conf=/etc/mha.cnf  #检查主从复制

#最后出现以下字段代表成功
MySQL Replication Health is OK.

start MHA

nohup masterha_manager --conf=/etc/mha.cnf  &> /data/masterha/app1/manager.log  &
# 指定配置文件并且放进程在后台运、剥离与终端的关系

Test failover

[root@node4 ~]# masterha_check_status --conf /etc/mha.cnf   #当前主节点为node1
mha (pid:2573) is running(0:PING_OK), master:172.16.1.2

[root@node1 ~]# service mysqld stop  #手动停止主节点

[root@node3 ~]# mysql
mysql> SHOW SLAVE STATUS\G;  

    Slave_IO_State: Waiting for master to send event
    Master_Host: 172.16.1.3  #已经转换为node2
    Master_User: rpuser
    Master_Port: 3306
    Connect_Retry: 60
    Master_Log_File: master-log.000006
    Read_Master_Log_Pos: 106
    Relay_Log_File: relay-log.000004
    Relay_Log_Pos: 252
    Relay_Master_Log_File: master-log.000006


[root@node2 ~]# mysql
mysql> SHOW GLOBAL VARIABLES LIKE '%read_only%';    #查看, read_only被MHA关闭了
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only     | OFF   |
+---------------+-------+
1 row in set (0.00 sec)

Summarize

In fact, our architecture is not complete enough. If we want to use it in the production environment, we need to provide a script to automatically switch VIPs. The front end uses a dedicated read-write separator for MySQL for scheduling, but due to time reasons, we won't go into more details here. , everyone can know that the basic usage is trivial compared to those

The level of the author is very low. If there are any mistakes, please point them out in time. If you think this article is well written, please give a like~(≧▽≦)/~ 
Author: AnyISaIln QQ: 1449472454 
Thanks: MageEdu