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香港服务器的MySQL之高可用组件MHA

2023/8/16 495次

香港服务器的MySQL之高可用组件MHA

1 简介

MHA（Master High Availability）是由日本人yoshinorim开发的一款成熟且开源的MySQL高可用程序，它实现了MySQL主从环境下MASTER宕机后能够自动进行单次故障转移的功能，其本身由perl语言编写，安装方便，使用简单

MHA Master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 Manager主要运行一些工具，比如masterha_manager工具实现自动监控MySQL Master和实现master故障切换，其它工具实现手动实现master故障切换、在线master转移、连接检查等

MHA Node部署在所有运行MySQL的服务器上，无论是master还是slave。主要作用有三个

Ⅰ、保存二进制日志 如果能够访问故障master，会拷贝master的二进制日志

II、应用差异中继日志 从拥有最新数据的slave上生成差异中继日志，然后应用差异日志

III、清除中继日志 在不停止SQL线程的情况下删除中继日志

MHA工作原理

从宕机崩溃的Master保存二进制日志事件（binlog event）；

识别含有最新更新的Slave；

应用差异的中继日志（relay log）到其他Slave；

应用从Master保存的二进制日志事件；

提升一个Slave为新的Master；

使其他的Slave连接新的Master进行复制；

MHA数据补偿

当SSH能连接,从库对比主库GTID 或者position号,立即将二进制日志保存至各个从节点并且应用(save_binary_logs )

当SSH不能连接, 对比从库之间的relaylog的差异(apply_diff_relay_logs)

2 环境部署

节点 ip

主节点 10.243.95.3

从节点1 10.243.95.4

从节点2 10.243.95.5

数据库复制一主两从架构，MHA node部署在每个节点上，MHA manager部署在从节点2上

2.1 建立SSH互信

#各节点生成rsa密钥

ssh-keygen -t rsa

#发送密钥至三台服务器实现互信

ssh-copy-id root@10.243.95.3

ssh-copy-id root@10.243.95.4

ssh-copy-id root@10.243.95.5

2.2 搭建主从复制

具体内容见上篇主从复制，注意mha57以下版本不支持GTID事务，需避雷，按需选择下面的部署方法

2.3 安装依赖包

2.3.1 MHA-0.57-el6版本

#1.所有节点安装以下依赖包

yum -y install perl-DBD-MySQL perl-ExtUtils-MakeMaker perl-CPAN

yum install -y perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-Time-HiRes

#2.所有节点安装mha-node包

rpm -ivh mha4mysql-node-0.57-0.el6.noarch.rpm

#3.管理节点安装mha-manage包

rpm -ivh mha4mysql-manager-0.57-0.el6.noarch.rpm

2.3.2 MHA-0.55-el6版本

#1.解压mha包

unzip -u mha_pack.zip

cd mha_pack/mha_pack/rhel6/mha2

#2.安装依赖

rpm -ivh perl-DBI-1.609-4.el6.x86_64.rpm

rpm -ivh perl-DBD-MySQL-4.013-3.el6.x86_64.rpm

rpm -ivh mha4mysql-node-0.54-0.el6.noarch.rpm

rpm -ivh perl-DBI-1.609-4.el6.x86_64.rpm

rpm -ivh perl-DBD-MySQL-4.013-3.el6.x86_64.rpm

rpm -ivh mha4mysql-node-0.54-0.el6.noarch.rpm

rpm -ivh perl-Config-Tiny-2.12-7.1.el6.noarch.rpm

rpm -ivh perl-TimeDate-1.16-11.1.el6.noarch.rpm

rpm -ivh perl-MailTools-2.04-4.el6.noarch.rpm

rpm -ivh perl-Email-Date-Format-1.002-5.el6.noarch.rpm

rpm -ivh perl-MIME-Types-1.28-2.el6.noarch.rpm

rpm -ivh perl-MIME-Lite-3.027-2.el6.noarch.rpm

rpm -ivh perl-Mail-Sender-0.8.16-3.el6.noarch.rpm

rpm -ivh perl-Mail-Sendmail-0.79-12.el6.noarch.rpm

rpm -ivh perl-Params-Validate-0.92-3.el6.x86_64.rpm

rpm -ivh perl-Log-Dispatch-2.27-1.el6.noarch.rpm

rpm -ivh perl-Parallel-ForkManager-0.7.9-1.el6.noarch.rpm

rpm -ivh perl-Time-HiRes-1.9721-127.el6.x86_64.rpm

rpm -ivh mha4mysql-manager-0.55-0.el6.noarch.rpm

2.4 配置文件

新建mha配置文件：vi /etc/masterha/app1.cnf

[server default]

# mysql root user and password

user=root

password=123456

# mysql log locations

#master_binlog_dir=/mysql/data

# user to use SSH around the cluster

ssh_user=root

# repl user and password

repl_user=repl

repl_password=123456

# working directory on the manager

manager_log=/root/mha/log/manager.log

manager_workdir=/root/mha/log

#remote_workdir=/mysql/mha/log

# MHA ping interval

ping_interval=5

## scripts to support MHA functions

## secondary_check_script= /usr/bin/masterha_secondary_check -s remote_host1 -s remote_host2

master_ip_failover_script= /root/mha/scripts/master_ip_failover

## shutdown_script= /usr/local/masterha/scripts/power_manager

## report_script= /usr/local/masterha/scripts/send_report

master_ip_online_change_script= /root/mha/scripts/master_ip_online_change

# masters

[server1]

hostname=10.243.95.3

port=3306

candidate_master=1

master_binlog_dir=/opt/mysql/binlog

remote_workdir=/root/mha/log

[server2]

hostname=10.243.95.4

port=3306

candidate_master=1

check_repl_delay=0

master_binlog_dir=/opt/mysql/binlog

remote_workdir=/root/mha/log

[server3]

hostname=10.243.95.5

port=3306

candidate_master=1

check_repl_delay=0

master_binlog_dir=/opt/mysql/binlog

remote_workdir=/root/mha/log

2.5 切换脚本

1）创建一些目录

#建立mha的文件夹

mkdir -p /root/mha/conf

mkdir -p /root/mha/log

mkdir -p /root/mha/scripts

chmod -R 777 /root/mha/scripts

2）新建脚本

在线切换脚本

vi /root/mha/scripts/master_ip_online_change

#!/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;

use MHA::DBHelper;

use MHA::NodeUtil;

use Time::HiRes qw( sleep gettimeofday tv_interval );

use Data::Dumper;

my $_tstart;

my $_running_interval = 0.1;

my (

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

$orig_master_port, $orig_master_user, $orig_master_password,

$new_master_host, $new_master_ip, $new_master_port,

$new_master_user, $new_master_password

);

my $vip = '192.168.90.30'; # writer Virtual IP

my $gw = `route|grep default|awk '{print \$2}'`;

chomp($gw);

my $interface = 'eth0'; # network interface

my $ssh_start_vip = "ip addr add $vip/32 dev $interface";

my $ssh_ping = "arping -U -I $interface -s $vip $gw -c 5";

my $ssh_stop_vip = "ip addr del $vip/32 dev $interface";

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,

'orig_master_user=s' => \$orig_master_user,

'orig_master_password=s' => \$orig_master_password,

'new_master_host=s' => \$new_master_host,

'new_master_ip=s' => \$new_master_ip,

'new_master_port=i' => \$new_master_port,

'new_master_user=s' => \$new_master_user,

'new_master_password=s' => \$new_master_password,

);

$ssh_user = 'root' unless ($ssh_user);

exit &main();

sub current_time_us {

my ( $sec, $microsec ) = gettimeofday();

my $curdate = localtime($sec);

return $curdate . " " . sprintf( "%06d", $microsec );

}

sub sleep_until {

my $elapsed = tv_interval($_tstart);

if ( $_running_interval > $elapsed ) {

sleep( $_running_interval - $elapsed );

}

}

sub get_threads_util {

my $dbh = shift;

my $my_connection_id = shift;

my $running_time_threshold = shift;

my $type = shift;

$running_time_threshold = 0 unless ($running_time_threshold);

$type = 0 unless ($type);

my @threads;

my $sth = $dbh->prepare("SHOW PROCESSLIST");

$sth->execute();

while ( my $ref = $sth->fetchrow_hashref() ) {

my $id = $ref->{Id};

my $user = $ref->{User};

my $host = $ref->{Host};

my $command = $ref->{Command};

my $state = $ref->{State};

my $query_time = $ref->{Time};

my $info = $ref->{Info};

$info =~ s/^\s*(.*?)\s*$/$1/ if defined($info);

next if ( $my_connection_id == $id );

next if ( defined($query_time) && $query_time < $running_time_threshold );

next if ( defined($command) && $command eq "Binlog Dump" );

next if ( defined($user) && $user eq "system user" );

next

if ( defined($command)

&& $command eq "Sleep"

&& defined($query_time)

&& $query_time >= 1 );

if ( $type >= 1 ) {

next if ( defined($command) && $command eq "Sleep" );

next if ( defined($command) && $command eq "Connect" );

}

if ( $type >= 2 ) {

next if ( defined($info) && $info =~ m/^select/i );

next if ( defined($info) && $info =~ m/^show/i );

}

push @threads, $ref;

}

return @threads;

}

sub main {

if ( $command eq "stop" ) {

## Gracefully killing connections on the current master

# 1. Set read_only= 1 on the new master

# 2. Set read_only= 1 on the current master

# 3. Kill current queries

# 4. Deegister original master's ip to the catalog database

# * Any database access failure will result in script die.

my $exit_code = 1;

eval {

## Setting read_only=1 on the new master (to avoid accident)

my $new_master_handler = new MHA::DBHelper();

# args: hostname, port, user, password, raise_error(die_on_error)_or_not

$new_master_handler->connect( $new_master_ip, $new_master_port,

$new_master_user, $new_master_password, 1 );

print current_time_us() . " Set read_only on the new master.. ";

$new_master_handler->enable_read_only();

if ( $new_master_handler->is_read_only() ) {

print "ok.\n";

}

else {

die "Failed!\n";

}

$new_master_handler->disconnect();

# Connecting to the orig master, die if any database error happens

my $orig_master_handler = new MHA::DBHelper();

$orig_master_handler->connect( $orig_master_ip, $orig_master_port,

$orig_master_user, $orig_master_password, 1 );

## Drop application user so that nobody can connect. Disabling per-session binlog beforehand

$orig_master_handler->disable_log_bin_local();

## Waiting for N * 100 milliseconds so that current connections can exit

my $time_until_read_only = 15;

$_tstart = [gettimeofday];

my @threads = get_threads_util( $orig_master_handler->{dbh},

$orig_master_handler->{connection_id} );

while ( $time_until_read_only > 0 && $#threads >= 0 ) {

if ( $time_until_read_only % 5 == 0 ) {

printf

"%s Waiting all running %d threads are disconnected.. (max %d milliseconds)\n",

current_time_us(), $#threads + 1, $time_until_read_only * 100;

if ( $#threads < 5 ) {

print Data::Dumper->new( [$_] )->Indent(0)->Terse(1)->Dump . "\n"

foreach (@threads);

}

}

sleep_until();

$_tstart = [gettimeofday];

$time_until_read_only--;

@threads = get_threads_util( $orig_master_handler->{dbh},

$orig_master_handler->{connection_id} );

}

## Setting read_only=1 on the current master so that nobody(except SUPER) can write

print current_time_us() . " Set read_only=1 on the orig master.. ";

$orig_master_handler->enable_read_only();

if ( $orig_master_handler->is_read_only() ) {

print "ok.\n";

}

else {

die "Failed!\n";

}

## Waiting for M * 100 milliseconds so that current update queries can complete

my $time_until_kill_threads = 5;

@threads = get_threads_util( $orig_master_handler->{dbh},

$orig_master_handler->{connection_id} );

while ( $time_until_kill_threads > 0 && $#threads >= 0 ) {

if ( $time_until_kill_threads % 5 == 0 ) {

printf

"%s Waiting all running %d queries are disconnected.. (max %d milliseconds)\n",

current_time_us(), $#threads + 1, $time_until_kill_threads * 100;

if ( $#threads < 5 ) {

print Data::Dumper->new( [$_] )->Indent(0)->Terse(1)->Dump . "\n"

foreach (@threads);

}

}

sleep_until();

$_tstart = [gettimeofday];

$time_until_kill_threads--;

@threads = get_threads_util( $orig_master_handler->{dbh},

$orig_master_handler->{connection_id} );

}

## Terminating all threads

print current_time_us() . " Killing all application threads..\n";

$orig_master_handler->kill_threads(@threads) if ( $#threads >= 0 );

print current_time_us() . " done.\n";

$orig_master_handler->enable_log_bin_local();

$orig_master_handler->disconnect();

## Deregister original master's VIP

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

&stop_vip();

$exit_code = 10;

## After finishing the script, MHA executes FLUSH TABLES WITH READ LOCK

$exit_code = 0;

};

if ($@) {

warn "Got Error: $@\n";

exit $exit_code;

}

exit $exit_code;

}

elsif ( $command eq "start" ) {

# 1. Register new master's ip to the catalog database

# We don't return error even though activating updatable accounts/ip failed so that we don't interrupt slaves' recovery.

# If exit code is 0 or 10, MHA does not abort

my $exit_code = 10;

eval {

## Update master ip on the catalog database, etc

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

&start_vip();

$exit_code = 0;

};

if ($@) {

warn "Got Error: $@\n";

exit $exit_code;

}

exit $exit_code;

}

elsif ( $command eq "status" ) {

# do nothing

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 \"`;

`ssh $ssh_user\@$new_master_host \" $ssh_ping \"`;

}

# 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_online_change --command=start|stop|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";

die;

}

注：若提示用户无repl权限且确认已添加，检查mysql.user表下的repl用户是否存在其它host存在repl权限为N的行，因为mha检查到任意行存在N即返回失败

2.6.3 故障自动切换验证

1、开启三个数据库节点实例，确保主从复制状态正常(执行2.6.2操作)

2、后台打开监控程序，并持续监控日志

4、完成切换

MySQL之高可用组件MHA

故障切换内容：

检查到master不通，尝试继续ping检查，达到阈值5触发自动切换

若配置文件未指定候选节点，根据日志量选举新的master主节点

若主节点未宕机，移除原master节点的vip

其他节点与新的master建立复制关系，主从复制同步中

新master节点启动vip，完成切换

2.6.4 手动切换

1）主节点已宕机

2）主节点未宕机

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