MHA

什么是MHA -------- MASTER HIGH AVAILABILITY

建立在主从复制基础之上的故障切换到软件系统

主从复制的单点问题：

• 当主从复制当中，主服务器发生故障，会自动切换到一台从服务器，然后把从服务器升格为主，继续主从的架构

1、master开启二进制日志，并允许从节点复制主节点的二进制日志的内容

2、通过vip地址，当主宕机之后，vip会自动飘移到从节点

3、从节点升级为主服务器，然后从宕机的master保存二进制日志，将更新的内容同步到新主，然后再同步到从节点

mysql1 192.168.31.18 主

mysql2 192.168.31.19 从1 ------ 主备

mysql3 192.168.31.20 从2

nginx1 192.168.31.16 MHA的组件

vip 192.168.31.100

主从复制+读写分离+mha，mysql初始化进行的操作

relay_log_recovery=1 ----------- 启用后，从库崩溃或重启时，会自动尝试从日志当中恢复

安装mha的组件：
node manager

node表示：监控每台机器上mysql的状态，传回给manager

manager：管理节点，控制mha的切换

配置所有节点之间的MHA的ssh的通信

#!/usr/bin/env perl
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 = '192.168.233.100';
my $brdc = '192.168.233.255';
my $ifdev = 'ens33';
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" ) {
my $exit_code = 1;
eval {
print "Disabling the VIP on old master: $orig_master_host \n";
&stop_vip();
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@\n";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {
my $exit_code = 10;
eval {
print "Enabling the VIP - $vip on the new master - $new_master_host \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";
exit 0;
}
else {
&usage();
exit 1;
}
}
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";
}

[server default]
manager_log=/var/log/masterha/app1/manager.log
manager_workdir=/var/log/masterha/app1
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
ping_interval=1
remote_workdir=/tmp
repl_password=123456
repl_user=myslave
secondary_check_script=/usr/local/bin/masterha_secondary_check -s 192.168.233.22 -s 192.168.233.23 
#从对主监听
shutdown_script=""
ssh_user=root
user=mha

[server1]
hostname=192.168.233.21 
#主服务器
port=3306

[server2]
candidate_master=1
#声明server2备份服务器 
check_repl_delay=0
#立刻切换
hostname=192.168.233.22  
#备用主服务器
port=3306

[server3]
hostname=192.168.233.23  
#从服务器2
port=3306

  $str =~ /(\d+)\.(\d+)/;
  my $strmajor = "$1.$2";
  my $result = sprintf( '%03d%03d', $1, $2 ) if $str =~ m/(\d+)\.(\d+)/;

masterha_check_ssh -conf=/etc/masterha/app1.cnf