一、MHA简介
1、MHA
Master High Availability，对主节点进行监控，可实现自动故障转移至其它从节点；通过提升某一从节点为新的主节点，基于主从复制实现，还需要客户端配合实现，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。
2、MHA集群架构
3、MHA的工作原理
(1) 从宕机崩溃的master保存二进制日志事件(binlog events)
(2) 识别含有最新更新的slave
(3) 应用差异的中继日志(relay log)到其他的slave
(4) 应用从master保存的二进制日志事件(binlog events)
(5) 提升一个slave为新的master
(6) 使其他的slave连接新的master进行复制
4、MHA软件组成
(1) Manager 工具包
Manager工具包主要包含以下几个工具：
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MHA
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 故障转移(自动或手动)
masterha_conf_host 添加或删除配置的server信息
(2) Node 工具包
Node工具包：(这些工具通常由MHA Manager的脚本触发，无需人为操作)主要包括以下几个工具：
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已不再使用此工具)
purge_relay_logs 清除中继日志(不会阻塞SQL线程)
注意：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 5.5的半同步复制
(3) 自定义扩展
secondary_check_script 通过多条网络路由检测master的可用性
master_ip_ailover_script 更新Application使用的masterip
shutdown_script 强制关闭master节点
report_script 发送报告
init_conf_load_script 加载初始配置参数
master_ip_online_change_script 更新master节点ip地址
(4) 配置文件:
global配置：为各application提供默认配置
application配置：为每个主从复制集群
二、实验环境
主机：4台，一台MHA Manager (192.168.214.17)，三台主从复制架构(一主多从)，master (192.168.214.27)，slave1 (192.168.214.37)，slave2 (192.168.214.47)
系统：CentOS7.6
数据库：mariadb-server-5.5.60（光盘yum源）
MHA软件包：mha4mysql-manager-0.56，mha4mysql-node-0.56
三、相关步骤
1、三台主从节点主点先安装mariadb数据库，使用光盘yum源
[[email protected]27 ~]# yum install -y mariadb-server [[email protected]-37 ~]# yum install -y mariadb-server [[email protected]-47 ~]# yum install -y mariadb-server
2、准备MHA软件包，MHA Manager节点需要mha4mysql-manager和mha4mysql-node，其它三个节点只需要mha4mysql-node
[[email protected]17 ~]# ll mha4mysql* -rw-r--r-- 1 root root 87119 Dec 9 10:32 mha4mysql-manager-0.56-0.el6.noarch.rpm -rw-r--r-- 1 root root 36326 Dec 9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm [[email protected]-27 ~]# ll mha4mysql* -rw-r--r-- 1 root root 36326 Dec 9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm [[email protected]-37 ~]# ll mha4mysql* -rw-r--r-- 1 root root 36326 Dec 9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm [[email protected]-47 ~]# ll mha4mysql* -rw-r--r-- 1 root root 36326 Dec 9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm
3、安装MHA软件包，MHA Manager节安装mha4mysql-manager时需要依赖epel源，这里使用阿里云的epel源
[[email protected]17 ~]# cat /etc/yum.repos.d/base.repo [development] name=dvdbase repo baseurl=file:///mnt/cdrom/ enabled=1 gpgcheck=1 gpgkey=file:///mnt/cdrom/RPM-GPG-KEY-CentOS-7 [aliyunEpel] name=aliyun epel baseurl=https://mirrors.aliyun.com/epel/$releasever/$basearch enabled=1 gpgcheck=1 gpgkey=https://mirrors.aliyun.com/epel/RPM-GPG-KEY-EPEL-$releasever [[email protected]17 ~]# yum install -y mha4mysql* [[email protected]-27 ~]# yum install -y mha4mysql-node-0.56-0.el6.noarch.rpm [[email protected]-37 ~]# yum install -y mha4mysql-node-0.56-0.el6.noarch.rpm [[email protected]-47 ~]# yum install -y mha4mysql-node-0.56-0.el6.noarch.rpm
4、配置主从复制(一主多从)
1). master节点
[[email protected]27 ~]# vim /etc/my.cnf [mysqld] server-id=27 #添加此项 bin-log #添加此项 skip_name_resolve=1 #添加此项 datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 # Settings user and group are ignored when systemd is used. # If you need to run mysqld under a different user or group, # customize your systemd unit file for mariadb according to the # instructions in http://fedoraproject.org/wiki/Systemd [mysqld_safe] log-error=/var/log/mariadb/mariadb.log pid-file=/var/run/mariadb/mariadb.pid # # include all files from the config directory # !includedir /etc/my.cnf.d
[[email protected]27 ~]# systemctl start mariadb [[email protected]-27 ~]# mysql Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 2 Server version: 5.5.60-MariaDB MariaDB Server Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement. MariaDB [(none)]> show master logs; +--------------------+-----------+ | Log_name | File_size | +--------------------+-----------+ | mariadb-bin.000001 | 245 | +--------------------+-----------+ 1 row in set (0.00 sec) MariaDB [(none)]> grant replication slave on *.* to [email protected]‘192.168.214.%‘ identified by ‘centos‘; #添加主从复制用户 Query OK, 0 rows affected (0.00 sec) MariaDB [(none)]> grant all on *.* to [email protected]‘192.168.214.%‘ identified by ‘mhauser‘; #添加mha管理用户 Query OK, 0 rows affected (0.00 sec)
2). slave节点，两台节点的配置一样，以slave1(192.168.214.37)为例
[[email protected]37 ~]# cat /etc/my.cnf
[mysqld]
server-id=37 #添加此项，slave2上的值记得改成47
log_bin #添加此项
read-only #添加此项
skip_name_resolve=1 #添加此项
relay_log_purge=0 #添加此项，是否清除中继日志，默认开启，这里把它关闭，因为需要用到中继日志
...以下省略[[email protected] ~]# systemctl start mariadb
[[email protected]-37 ~]# mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 6
Server version: 5.5.60-MariaDB MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.
MariaDB [(none)]> CHANGE MASTER TO #配置连接主节点的信息
-> MASTER_HOST=‘192.168.214.27‘, #主节点IP
-> MASTER_USER=‘repluser‘, #用于复制的账号
-> MASTER_PASSWORD=‘centos‘, #密码
-> MASTER_LOG_FILE=‘mariadb-bin.000001‘, #要复制的二进制日志
-> MASTER_LOG_POS=245; #开始复制的二进制日志的位置
Query OK, 0 rows affected (0.01 sec)
MariaDB [(none)]> start slave; #开启复制线程
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> show slave status\G; #可用于查看开启状态
5、配置MHA Manager主机和其它三台主机的基于key验证的ssh服务
[[email protected]17 ~]# ssh-keygen #生成密钥 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:F8VxSwWdphlQLd1J9csOHEW932/ZIhi6agC2BxDJ89A [email protected] The key‘s randomart image is: +---[RSA 2048]----+ |oo. o=oOBO| |o+ E ..=.B=| | .+ . .B o| | +. ..oo..| | . + S . o oo| | . o .. o o| | . . . o .+| | . . . . ..+| | ..... . o | +----[SHA256]-----+ [[email protected]-17 ~]# ls -a .ssh . .. id_rsa id_rsa.pub known_hosts #拷贝公钥到本地，然后把本地的.ssh文件夹复制到其它三台主机的/root/目录下 #即可实现四台主机之前相互之间都可以互机登录而不用输密码 #如果只是配置MHA Manage登陆其它三台，只需要用以下命令 # ssh-copy-id -i /root/.ssh/id_rsa.pub [email protected]192.168.214.27 [[email protected]-17 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub [email protected]192.168.214.17 [[email protected]-17 ~]# scp -r .ssh [email protected]192.168.214.27:/root/ [[email protected]-17 ~]# scp -r .ssh [email protected]192.168.214.37:/root/ [[email protected]-17 ~]# scp -r .ssh [email protected]192.168.214.47:/root/
6、配置MHA Manager节点的配置文件
[[email protected]17 ~]# mkdir /etc/mha/ [[email protected]-17 ~]# vim /etc/mha/app1.cnf [server default] user=mhauser #管理用户 password=mhauser #密码 manager_workdir=/data/mastermha/app1/ manager_log=/data/mastermha/app1/manager.log remote_workdir=/data/mastermha/app1/ ssh_user=root #ssh用户 repl_user=repluser #复制用户 repl_password=centos #密码 ping_interval=1 #监测master的时间1s [server1] hostname=192.168.214.27 candidate_master=1 #此选项表示优先使用此主节点 [server2] hostname=192.168.214.37 candidate_master=1 [server3] hostname=192.168.214.47
7、验证与启动
[[email protected]17 ~]# masterha_check_ssh --conf=/etc/mha/app1.cnf #验证ssh [[email protected]-17 ~]# masterha_check_repl --conf=/etc/mha/app1.cnf #验证主从复制 [[email protected]-17 ~]# masterha_manager --conf=/etc/mha/app1.cnf #启动
注意：masterha_manager --conf=/etc/mha/app1.cnf 这种启动是一次性的(完成一次切换后就退出了)，且只是在当前会话；建议后台启动运行：nohup masterha_manager --conf=/etc/mha/app1.cnf > mha.log
8、测试当mater节点断开时，主从的切换
[[email protected]27 ~]# systemctl stop mariadb #关闭主节点数据库服务
[[email protected]-37 ~]# mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 21
Server version: 5.5.60-MariaDB MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.
MariaDB [(none)]> show slave status\G; #查询为空，说明slave1节点已提升为主节点
Empty set (0.00 sec)
MariaDB [(none)]> show variables like ‘read_only‘; #slave1节点的read-only选项也关闭了
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only | OFF |
+---------------+-------+
1 row in set (0.00 sec)
[[email protected]-47 ~]# mysql
MariaDB [(none)]> show slave status\G; #在slave2上查看
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.214.37 #当节点变为了slave1
Master_User: repluser
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 245
Relay_Log_File: mariadb-relay-bin.000002
Relay_Log_Pos: 531
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
...以下省略
原文地址：https://www.cnblogs.com/hovin/p/12009708.html