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运维工程师必备技能(上):MySQL MHA高可用及多主多从

删库跑路吧 529

前言:

而今我们对“mysql57主从搭建”都比较关心,姐妹们都想要剖析一些“mysql57主从搭建”的相关资讯。那么小编同时在网络上网罗了一些关于“mysql57主从搭建””的相关知识,希望我们能喜欢,姐妹们一起来了解一下吧!

由于头条篇幅限制,分上下两部分呈现,你现在看的是上半部分。谢谢!!

技能目标:

· 了解什么是MySQL MHA

· 学会如何搭建MySQL MHA

· 学会MySQL MHA故障切换

7.1 案例分析

7.1.1 案例概述

目前MySQL已经成为市场主流数据库的一种,考虑到业务的重要性,MySQL数据库单点问题已成为企业网站架构中最大的隐患,随着技术的发展,MHA的出现就是解决MySQL单点的问题,另外随着企业数据量越来越庞大,数据库的压力又成为企业的另一个瓶颈,MySQL的多主多从的架构的出现可以减轻MySQL的压力。本章将主要介绍MHA的搭建和模拟MySQL故障自动切换的过程,介绍搭建MySQL多主多从的详细过程。

7.1.2 案例前置知识点

1.什么是MHA

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,它由日本DeNA公司youshimaton(现就职于Facebook公司)开发,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。

2. MHA的组成

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。

3. MHA优势

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。

4. MHA现状

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。有兴趣的可以试试。

7.1.3 案例环境

1. 本案例环境

本案例环境如表7-1所示。

表7-1 搭建MySQL MHA高可用案例环境

本实例中用到MYSQL版本请从官网进行下载,MHA的版本请从一些相关资源进行下载,因为google官网上面最新的还是2012年0.55版本,而且0.55版本只支持到CentOS6,这里操作系统是CentOS7版本,所以这里下载MHA版本是0.57版本。MHA架构如下图7.1所示:

图7.1

上图中MHA可以同时监控并管理多个MySQL复制组,本案例只实验其中的一个复制组,具体拓扑图如下图7.2所示:

图7.2

2. 案例需求

本案例要求通过MHA监控MySQL数据库在故障时进行自动切换,不影响业务。

3. 案例实现思路

1) 安装MySQL数据库

2) 配置MySQL一主两从

3) 安装MHA软件

4) 配置无密码认证

5) 配置MySQL MHA高可用

6) 模拟master故障切换

7.2 案例实施

7.2.1 安装MySQL数据库

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。下面只在Mysql1上面做演示,安装过程如下:

1. 首先安装编译依赖的环境

[root@Mysql1 ~]# yum -y install ncurses-devel gcc-c++ perl-Module-Install

2. 安装gmake编译软件

[root@Mysql1 ~]# tar zxvf cmake-2.8.6.tar.gz

[root@Mysql1 ~]# cd cmake-2.8.6

[root@Mysql1 cmake-2.8.6]# ./configure

[root@Mysql1 cmake-2.8.6]# gmake && gmake install

3. 安装mysql数据库

[root@Mysql1 ~]# tar -zxvf mysql-5.6.36.tar.gz

[root@Mysql1 ~]# cd mysql-5.6.36

[root@Mysql1 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

[root@Mysql1 mysql-5.6.36]# make && make install

[root@Mysql1 mysql-5.6.36]# cp support-files/my-default.cnf /etc/my.cnf

[root@Mysql1 mysql-5.6.36]# cp support-files/mysql.server /etc/rc.d/init.d/mysqld

[root@Mysql1 ~]# chmod +x /etc/rc.d/init.d/mysqld

[root@Mysql1 ~]# chkconfig --add mysqld

[root@Mysql1 ~]# echo "PATH=$PATH:/usr/local/mysql/bin" >> /etc/profile

[root@Mysql1 ~]# source /etc/profile

[root@Mysql1 ~]# groupadd mysql

[root@Mysql1 ~]# useradd -M -s /sbin/nologin mysql -g mysql

[root@Mysql1 ~]# chown -R mysql.mysql /usr/local/mysql

[root@Mysql1 ~]# mkdir -p /data/mysql

[root@Mysql1 ~]# /usr/local/mysql/scripts/mysql_install_db --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --user=mysql

4. 修改Master的主配置文件/etc/my.cnf文件,三台服务器的server-id不能一样,另外两台写2和3即可!写入内容如下:

[root@Mysql1 ~]# cat /etc/my.cnf

[mysqld]

server-id = 1

log_bin = master-bin

log-slave-updates = true

配置从服务器。

在/etc/my.cnf中修改或者增加下面内容。

[root@Mysql2 ~]# vim /etc/my.cnf

server-id = 2 //增加

relay-log = relay-log-bin //增加

relay-log-index = slave-relay-bin.index //增加

这里要注意server-id不能相同。

5. Mysql1、Mysql2、Mysql3分别做两个软链接,软链接是为HMA服务的

[root@Mysql1 ~]# ln -s /usr/local/mysql/bin/mysql /usr/sbin/

[root@Mysql1 ~]# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/sbin/

6、Mysql1、Mysql2、Mysql3启动mysql

[root@Mysql1 ~]# /usr/local/mysql/bin/mysqld_safe --user=mysql &

7.2.2 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'@'192.168.8.%' identified by '123';

mysql> grant all privileges on *.* to 'mha'@'192.168.8.%' identified by 'manager';

2. 下面三条授权按理论是不用添加的,但是做案例实验环境时候通过MHA检查MySQL主从有报错,报两个从库通过主机名连接不上主库,所以所有数据库加上下面的授权。

mysql> grant all privileges on *.* to 'mha'@'Mysql1' identified by 'manager';

mysql> grant all privileges on *.* to 'mha'@'Mysql2' identified by 'manager';

mysql> grant all privileges on *.* to 'mha'@'Mysql3' identified by 'manager';

3. 在Mysql1主机上查看二进制文件和同步点,如图7.3

图7.3

4. 接下来在Mysql2和Mysql3分别执行同步

mysql> change master to master_host='192.168.8.134',master_user='myslave',master_password='123',master_log_file='mysql-bin.000001',master_log_pos=675; 和上一章保持一致

mysql> start slave;

5. 查看IO和SQL线程都是yes代表同步是否正常

mysql> show slave status\G;

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

必须设置两个从库为只读模式

mysql> set global read_only=1;

6. 在Mysql1主库插入两条数据,测试是否同步

mysql> create database test_db;

Query OK, 1 row affected (0.00 sec)

mysql> use test_db;

Database changed

mysql> create table test(id int);

Query OK, 0 rows affected (0.13 sec)

mysql> insert into test(id) values (1);

Query OK, 1 row affected (0.03 sec)

7. 在两个从库分别查询如下所示说明主从同步正常

mysql> select * from test_db.test;

+------+

| id |

+------+

| 1 |

+------+

1 row in set (0.00 sec)

7.2.3 安装MHA软件

1. 所有服务器上都安装MHA依赖的环境,首先安装epel源。

[root@MHA-manager ~]# yum install -y epel-release

[root@MHA-manager ~]# yum install -y perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-ExtUtils-CBuilder perl-ExtUtils-MakeMaker perl-CPAN

2. MHA软件包对于每个操作系统版本不一样,这里CentOS7.3必须选择0.57版本,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,下面都是在Mysql1上操作演示安装node组件。

[root@Mysql1 ~]# tar zxvf mha4mysql-node-0.57.tar.gz

[root@Mysql1 ~]# cd mha4mysql-node-0.57

[root@Mysql1 mha4mysql-node-0.57]# perl Makefile.PL

[root@Mysql1 mha4mysql-node-0.57]# make

[root@Mysql1 mha4mysql-node-0.57]# make install

3. 在MHA-manager上安装manager组件

[root@MHA-manager ~]# tar zxvf mha4MHA-manager-0.57.tar.gz [root@MHA-manager ~]# cd mha4MHA-manager-0.57

[root@MHA-manager mha4MHA-manager-0.57]# perl Makefile.PL

*** Module::AutoInstall version 1.06

*** 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. (7.18)

- MHA::NodeConst ...loaded. (0.57)

*** Module::AutoInstall configuration finished.

Checking if your kit is complete...

Looks good

Writing Makefile for mha4mysql::manager

[root@MHA-manager mha4MHA-manager-0.57]# make

[root@MHA-manager mha4MHA-manager-0.57]# make install

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 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

4. 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)

7.2.4 配置无密码认证

1. 在manager上配置到所有节点的无密码认证

[root@MHA-manager ~]# ssh-keygen -t rsa //一路按回车键

[root@MHA-manager ~]# ssh-copy-id 192.168.8.134

[root@MHA-manager ~]# ssh-copy-id 192.168.8.136

[root@MHA-manager ~]# ssh-copy-id 192.168.8.139

2. 在Mysql1上配置到数据库节点的无密码认证

[root@Mysql1 ~]# ssh-keygen -t rsa

[root@Mysql1 ~]# ssh-copy-id 192.168.8.136

[root@Mysql1 ~]# ssh-copy-id 192.168.8.139

3. 在Mysql2上配置到数据库节点的无密码认证

[root@Mysql2 ~]# ssh-keygen -t rsa

[root@Mysql2 ~]# ssh-copy-id 192.168.8.134

[root@Mysql2 ~]# ssh-copy-id 192.168.8.139

4. 在Mysql3上配置到数据库节点的无密码认证

[root@Mysql3 ~]# ssh-keygen -t rsa

[root@Mysql3 ~]# ssh-copy-id 192.168.8.134

[root@Mysql3 ~]# ssh-copy-id 192.168.8.136

7.2.5 配置MHA

1. 在manager节点上复制相关脚本到/usr/local/bin目录

[root@MHA-manager ~]# cp -ra /root/mha4MHA-manager-0.57/samples/scripts /usr/local/bin

拷贝后会有四个执行文件

[root@atlas ~]# ll /usr/local/bin/scripts/

总用量 32

-rwxr-xr-x 1 mysql mysql 3648 5月 31 2015 master_ip_failover

-rwxr-xr-x 1 mysql mysql 9872 5月 25 09:07 master_ip_online_change

-rwxr-xr-x 1 mysql mysql 11867 5月 31 2015 power_manager

-rwxr-xr-x 1 mysql mysql 1360 5月 31 2015 send_report

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. 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,也是推荐的一种方式,生产环境不太建议使用keepalived。

[root@MHA-manager ~]# cp /usr/local/bin/scripts/master_ip_failover /usr/local/bin

3. 修改内容如下:

[root@MHA-manager ~]# cat /usr/local/bin/master_ip_failover

#!/usr/bin/env perl

# Copyright (C) 2011 DeNA Co.,Ltd.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc.,

# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

## Note: This is a sample script and is not complete. Modify the script based on your environment.

use strict;

use warnings FATAL =>'all';

use Getopt::Long;

my (

$command, $ssh_user, $orig_master_host, $orig_master_ip,

$orig_master_port, $new_master_host, $new_master_ip, $new_master_port

);

my $vip = '192.168.8.200/24';

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;

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,

);

exit &main();

sub main {

#print "\n\nIN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===\n\n";

if ( $command eq "stop" || $command eq "stopssh" ) {

# $orig_master_host, $orig_master_ip, $orig_master_port are passed.

# If you manage master ip address at global catalog database,

# invalidate orig_master_ip here.

my $exit_code = 1;

eval {

print "\n\n\n***************************************************************\n";

print "Disabling the VIP - $vip on old master: $orig_master_host\n";

print "***************************************************************\n\n\n\n";

&stop_vip();

$exit_code = 0;

};

if ($@) {

warn "Got Error: $@\n";

exit $exit_code;

}

exit $exit_code;

}

elsif ( $command eq "start" ) {

# all arguments are passed.

# If you manage master ip address at global catalog database,

# activate new_master_ip here.

# You can also grant write access (create user, set read_only=0, etc) here.

my $exit_code = 10;

eval {

print "\n\n\n***************************************************************\n";

print "Enabling the VIP - $vip on new master: $new_master_host \n";

print "***************************************************************\n\n\n\n";

&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 \n";

`ssh $ssh_user\@$orig_master_host \" $ssh_start_vip \"`;

exit 0;

}

else {

&usage();

exit 1;

}

}

# A simple system call that enable the VIP on the new master

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 \"`;

}

sub usage {

print

"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\n";

}

4. 创建MHA软件目录并拷贝配置文件

[root@MHA-manager ~]# mkdir /etc/masterha

[root@MHA-manager ~]# cp /root/mha4MHA-manager-0.57/samples/conf/app1.cnf /etc/masterha

[root@MHA-manager ~]# cat /etc/masterha/app1.cnf

[server default]

manager_workdir=/var/log/masterha/app1

manager_log=/var/log/masterha/app1/manager.log

master_binlog_dir=/usr/local/mysql/data

master_ip_failover_script= /usr/local/bin/master_ip_failover

master_ip_online_change_script= /usr/local/bin/master_ip_online_change

password=manager

user=mha

ping_interval=1

remote_workdir=/tmp

repl_password=123

repl_user=myslave

secondary_check_script= /usr/local/bin/masterha_secondary_check -s 192.168.8.136 -s 192.168.8.139

shutdown_script=""

ssh_user=root

[server1]

hostname=192.168.8.134

port=3306

[server2]

hostname=192.168.8.136

port=3306

candidate_master=1

check_repl_delay=0

[server3]

hostname=192.168.8.139

port=3306

5. 测试ssh无密码认证,如果正常最后会输出successfully,如图1.6

[root@MHA-manager ~]# masterha_check_ssh -conf=/etc/masterha/app1.cnf

Thu May 17 14:07:29 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.

Thu May 17 14:07:29 2018 - [info] Reading application default configuration from /etc/masterha/app1.cnf..

Thu May 17 14:07:29 2018 - [info] Reading server configuration from /etc/masterha/app1.cnf..

Thu May 17 14:07:29 2018 - [info] Starting SSH connection tests..

Thu May 17 14:07:30 2018 - [debug]

Thu May 17 14:07:29 2018 - [debug] Connecting via SSH from root@192.168.8.134(192.168.8.134:22) to root@192.168.8.136(192.168.8.136:22)..

Thu May 17 14:07:30 2018 - [debug] ok.

Thu May 17 14:07:30 2018 - [debug] Connecting via SSH from root@192.168.8.134(192.168.8.134:22) to root@192.168.8.139(192.168.8.139:22)..

Thu May 17 14:07:30 2018 - [debug] ok.

Thu May 17 14:07:31 2018 - [debug]

Thu May 17 14:07:30 2018 - [debug] Connecting via SSH from root@192.168.8.136(192.168.8.136:22) to root@192.168.8.134(192.168.8.134:22)..

Thu May 17 14:07:30 2018 - [debug] ok.

Thu May 17 14:07:30 2018 - [debug] Connecting via SSH from root@192.168.8.136(192.168.8.136:22) to root@192.168.8.139(192.168.8.139:22)..

Thu May 17 14:07:30 2018 - [debug] ok.

Thu May 17 14:07:32 2018 - [debug]

Thu May 17 14:07:30 2018 - [debug] Connecting via SSH from root@192.168.8.139(192.168.8.139:22) to root@192.168.8.134(192.168.8.134:22)..

Thu May 17 14:07:31 2018 - [debug] ok.

Thu May 17 14:07:31 2018 - [debug] Connecting via SSH from root@192.168.8.139(192.168.8.139:22) to root@192.168.8.136(192.168.8.136:22)..

Thu May 17 14:07:31 2018 - [debug] ok.

Thu May 17 14:07:32 2018 - [info] All SSH connection tests passed successfully.

6. 测试mysq主从连接情况,最后出现MySQL Replication Health is OK字样说明正常。如下所示:

[root@MHA-manager ~]# masterha_check_repl -conf=/etc/masterha/app1.cnf

Thu May 17 16:44:55 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.

Thu May 17 16:44:55 2018 - [info] Reading application default configuration from /etc/masterha/app1.cnf..

Thu May 17 16:44:55 2018 - [info] Reading server configuration from /etc/masterha/app1.cnf..

Thu May 17 16:44:55 2018 - [info] MHA::MasterMonitor version 0.57.

Thu May 17 16:44:56 2018 - [info] GTID failover mode = 0

Thu May 17 16:44:56 2018 - [info] Dead Servers:

Thu May 17 16:44:56 2018 - [info] Alive Servers:

Thu May 17 16:44:56 2018 - [info] 192.168.8.134(192.168.8.134:3306)

Thu May 17 16:44:56 2018 - [info] 192.168.8.136(192.168.8.136:3306)

Thu May 17 16:44:56 2018 - [info] 192.168.8.139(192.168.8.139:3306)

Thu May 17 16:44:56 2018 - [info] Alive Slaves:

Thu May 17 16:44:56 2018 - [info] Checking replication filtering settings..

Thu May 17 16:44:56 2018 - [info] binlog_do_db= , binlog_ignore_db=

Thu May 17 16:44:56 2018 - [info] Replication filtering check ok.

......//省略部分

Cleaning up test file(s).. done.

Thu May 17 16:45:00 2018 - [info] Slaves settings check done.

Thu May 17 16:45:00 2018 - [info]

192.168.8.134(192.168.8.134:3306) (current master)

+--192.168.8.136(192.168.8.136:3306)

+--192.168.8.139(192.168.8.139:3306)

Thu May 17 16:45:00 2018 - [info] Checking replication health on 192.168.8.136..

Thu May 17 16:45:00 2018 - [info] ok.

Thu May 17 16:45:00 2018 - [info] Checking replication health on 192.168.8.139..

Thu May 17 16:45:00 2018 - [info] ok.

Thu May 17 16:45:00 2018 - [info] Checking master_ip_failover_script status:

Thu May 17 16:45:00 2018 - [info] /usr/local/bin/master_ip_failover --command=status --ssh_user=root --orig_master_host=192.168.8.134 --orig_master_ip=192.168.8.134 --orig_master_port=3306

Checking the Status of the script.. OK

Thu May 17 16:45:00 2018 - [info] OK.

Thu May 17 16:45:00 2018 - [warning] shutdown_script is not defined.

Thu May 17 16:45:00 2018 - [info] Got exit code 0 (Not master dead).

MySQL Replication Health is OK.

7. 启动MHA,下面是具体参数说明

[root@MHA-manager ~]# 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 &

--remove_dead_master_conf 该参数代表当发生主从切换后,老的主库的ip将会从配置文件中移除。 --manger_log 日志存放位置 --ignore_last_failover 在缺省情况下,如果MHA检测到连续发生宕机,且两次宕机间隔不足8小时的话,则不会进行Failover,之所以这样限制是为了避免ping-pong效应。该参数代表忽略上次MHA触发切换产生的文件,默认情况下,MHA发生切换后会在日志记目录,也就是上面设置的日志app1.failover.complete文件,下次再次切换的时候如果发现该目录下存在该文件将不允许触发切换,除非在第一次切换后收到删除该文件,为了方便,这里设置为–ignore_last_failover

8. 查看MHA状态,可以看到当前的master是Mysql1节点

[root@MHA-manager ~]# masterha_check_status --conf=/etc/masterha/app1.cnf

app1 (pid:7763) is running(0:PING_OK), master:192.168.8.134

9. 查看MHA日志,也以看到当前的master是192.168.8.134,如下图1.8所示:

[root@MHA-manager ~]# cat /var/log/masterha/app1/manager.log

Thu May 17 16:49:48 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.

Thu May 17 16:49:48 2018 - [info] Reading application default configuration from /etc/masterha/app1.cnf..

Thu May 17 16:49:48 2018 - [info] Reading server configuration from /etc/masterha/app1.cnf..

Thu May 17 16:49:48 2018 - [info] MHA::MasterMonitor version 0.57.

Thu May 17 16:49:49 2018 - [info] GTID failover mode = 0

Thu May 17 16:49:49 2018 - [info] Dead Servers:

Thu May 17 16:49:49 2018 - [info] Alive Servers:

Thu May 17 16:49:49 2018 - [info] 192.168.8.134(192.168.8.134:3306)

Thu May 17 16:49:49 2018 - [info] 192.168.8.136(192.168.8.136:3306)

Thu May 17 16:49:49 2018 - [info] 192.168.8.139(192.168.8.139:3306)

......//省略部分

Testing mysqlbinlog output.. done.

Cleaning up test file(s).. done.

Thu May 17 16:49:54 2018 - [info] Slaves settings check done.

Thu May 17 16:49:54 2018 - [info]

192.168.8.134(192.168.8.134:3306) (current master)

+--192.168.8.136(192.168.8.136:3306)

+--192.168.8.139(192.168.8.139:3306)

Thu May 17 16:49:54 2018 - [info] Checking master_ip_failover_script status:

Thu May 17 16:49:54 2018 - [info] /usr/local/bin/master_ip_failover --command=status --ssh_user=root --orig_master_host=192.168.8.134 --orig_master_ip=192.168.8.134 --orig_master_port=3306

Checking the Status of the script.. OK

Thu May 17 16:49:54 2018 - [info] OK.

Thu May 17 16:49:54 2018 - [warning] shutdown_script is not defined.

Thu May 17 16:49:54 2018 - [info] Set master ping interval 1 seconds.

Thu May 17 16:49:54 2018 - [info] Set secondary check script: /usr/local/bin/masterha_secondary_check -s 192.168.8.136 -s 192.168.8.139

Thu May 17 16:49:54 2018 - [info] Starting ping health check on 192.168.8.134(192.168.8.134:3306)..

Thu May 17 16:49:54 2018 - [info] Ping(SELECT) succeeded, waiting until MySQL doesn't respond..

10. 查看Mysql1的VIP地址192.168.8.200是否存在?,这个VIP地址不会因为manager节点停止MHA服务而消失

[root@Mysql1 ~]# ifconfig

ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

inet 192.168.8.134 netmask 255.255.255.0 broadcast 192.168.8.255

inet6 fe80::20c:29ff:feeb:b2c5 prefixlen 64 scopeid 0x20<link>

ether 00:0c:29:eb:b2:c5 txqueuelen 1000 (Ethernet)

RX packets 32494 bytes 19929135 (19.0 MiB)

RX errors 0 dropped 0 overruns 0 frame 0

TX packets 20439 bytes 3094488 (2.9 MiB)

TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

ens33:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

inet 192.168.8.200 netmask 255.255.255.0 broadcast 192.168.8.255

ether 00:0c:29:eb:b2:c5 txqueuelen 1000 (Ethernet)

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