MySQL MHA高可用方案

Posted 2020-09-14 小樽的雨后

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http://www.cnblogs.com/chenmh/p/5796115.html

介绍

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，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。它由两部分组成：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。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。

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；

MHA软件由两部分组成，Manager工具包和Node工具包

Manager工具包主要包括以下几个工具：

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          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

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已不再使用这个工具）
purge_relay_logs                清除中继日志（不会阻塞SQL线程）

一、安装MHA

1.创建安装目录

Node服务器安装

mkdir -p /usr/local/mha

manage服务器安装

mkdir -p /usr/local/mha/ha1/fail_script

mkdir -p /usr/local/mha/ha1/workdir

/usr/local/mha：程序安装目录

/usr/local/mha/ha1:用于区别每一个mha方案，当前方案ha1

/usr/local/mha/ha1/fail_script：方案ha1的failover脚本保存路径

/usr/local/mha/ha1/workdir:方案ha1的的日志和failover产生的binlog保存路径

2.安装epel插件

使用yum方式安装，需要安装epel源

epel源

wget http://mirrors.ustc.edu.cn/fedora/epel/6/x86_64/epel-release-6-8.noarch.rpm

所有服务器都安装(mananage需要安装以下所有插件,node节点只需要安装perl-DBD-MySQL,cpan)

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

也可以使用perl方式安装

#!/bin/bash
wget http://xrl.us/cpanm --no-check-certificate
mv cpanm /usr/bin
chmod 755 /usr/bin/cpanm
cat > /root/list << EOF
install DBD::mysql
install Config::Tiny
install Log::Dispatch
install Parallel::ForkManager
install Time::HiRes
install CPAN
install Digest::SHA
EOF
for package in `cat /root/list`
do
    cpanm $package
done

3.安装MHA Node软件包,所有服务器都要安装

tar -xvf mha4mysql-node-0.54.tar.gz
cd mha4mysql-node-0.54
perl Makefile.PL INSTALL_BASE=/usr/local/mha
make && make install

4.安装MHA Manager软件包,只在Manager主机上安装

tar -xvf mha4mysql-manager-0.55.tar.gz 
cd mha4mysql-manager-0.55
perl Makefile.PL INSTALL_BASE=/usr/local/mha
make && make install

cp samples/scripts/* /usr/local/mha/bin/

master_ip_failover:自动切换时vip管理的脚本

master_ip_online_change:手动切换使用的脚本

power_manager:故障发生后关闭主机的脚本

send_report:发送报警的脚本。

5.修改环境变量

将MHA Manager主机的/usr/local/mha/bin加入环境变量

6.添加软链接

为了不麻烦所有服务器都执行吧，其实最后两个mysql,mysqlbinlog的软链接只有Node服务器需要添加，其它的所有服务器都需要添加。

mkdir -p /usr/local/bin
mkdir -p /usr/local/share/man/man1
mkdir -p /usr/local/share/perl5/MHA
ln -s /usr/local/mha/bin/* /usr/local/bin;
ln -s /usr/local/mha/man/man1/* /usr/local/share/man/man1;
ln -s /usr/local/mha/lib/perl5/MHA /usr/local/share/perl5/MHA;
ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog;
ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql;

二、配置MHA

1.配置SSH无密码登入

（1）在manage配置到所有Node节点的无密码登入

ssh-keygen -t rsa   一直enter,会在/root/.ssh/下面生成id_rsa.pub
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.10 
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.20
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.30

(2)在Node 10配置到Node 20,30的无密码登入

ssh-keygen -t rsa 
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.20
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.30

(3)在Node 20配置到Node 10,30的无密码登入

ssh-keygen -t rsa 
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.10
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.30

(4)在Node 30配置到Node 10,20的无密码登入

ssh-keygen -t rsa 
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.10
ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.137.20

2. 搭建复制环境

复制环境之前已经搭建好，可以参考我前面写过的文章,复制用户和密码都是repl;每个Node上都必须创建这个repl账号，除非Node不作为故障专业的master

1.在所有Node上创建Manage监控用户

grant all privileges on *.* to \'root\'@\'192.168.137.%\' identified  by \'root\';

三、配置Manage

1.配置启动文件

vim /usr/local/mha/ha1/ha1.cnf

[server default]
manager_workdir=/usr/local/mha/ha1/workdir  ##项目的主目录
manager_log=/usr/local/mha/ha1/workdir/manager.log  ###mha记录日志
master_binlog_dir=/mysql/log  ####node服务器的binlog存放路径，如果每个node的binlog路径不一致的话就在下面的每个server下面单独配置
master_ip_failover_script=/usr/local/mha/ha1/fail_script/master_ip_failover  ####mha在线自动failover时处理VIP的配置文件
master_ip_online_change_script=/usr/local/mha/ha1/fail_script/master_ip_online_change  ####在线手动执行master切换时VIP的处理文件
secondary_check_script=/usr/local/mha/bin/masterha_secondary_check -s backup -s master --user=root --master_host=master --master_ip=192.168.137.10 --master_port=3306  ##一旦MHA到master之间的网络出现问题，manager会尝试从backup登入到masger
#report_script=/usr/local/mha/ha1/fail_script/send_report  ###发生切换后执行的报警脚本
shutdown_script="" ####故障后关闭master主机的脚本（主要是使用keepalive做VIP时会出现脑裂导致VIP频繁切换所以会将故障的master关闭）
ping_interval=1 ###监控mater，ping的频率
remote_workdir=/tmp  ###node服务器在发生master切换时，binlog保持的路径，每个node都会在该目录下保存一份差异的binlog，除非没有差异。
repl_password=repl   ##复制使用的用户名，每个node服务器都需要存在
repl_user=repl       ##复制使用的密码
user=root            ##mnager监控用的mysql root用户
password=root        ##root用户密码
ssh_user=root        ##ssh登入用户名

[server1]
hostname=192.168.137.10
port=3306
candidate_master=1
check_repl_delay=0


[server2]
hostname=192.168.137.20
port=3306
#master_binlog_dir=/mysql/log   
candidate_master=1   ##设置为候选master，如果设置该参数以后，发生主从切换以后将会将此从库提升为主库，即使这个主库不是集群中事件最新的slave
check_repl_delay=0   ##默认情况下如果一个slave落后master 100M的relay logs的话，MHA将不会选择该slave作为一个新的master，因为对于这个slave的恢复需要花费很长时间，通过设置check_repl_delay=0,MHA触发切换在选择一个新master的时候将会忽略复制延时，这个参数对于设置了candidate_master=1的主机非常有用，因为这个候选主在切换的过程中一定是新的master


[server3]
hostname=192.168.137.30
port=3306
ignore_fail=1  ####如果不加上该参数，当该slave主机故障了，mha将无法启动，加上该参数会忽略该主机是否正常，在mha启动的时候加上参数--ignore_fail_on_start 
no_master=1  ###不将该主机转换为master

注意：对于上面的配置一定要确保server1和server2之间是最新的binlog,一般会配置二者为双主的半同步复制，这样就保证了它们之间的binlog是最新的，否则应用差异的binlog将花费非常长的时间（如果它们和master延时非常大的情况下）

2.master_ip_failover

VIP的配置可以使用keepalived也可以写脚本，keepalived对网络的要求很高否则容易脑裂，在我前面搭建双主环境讲过keepalived的搭建方法，我这里使用脚本的方式。

View Code

注意：需要手动先在master服务器上面添加VIP

/sbin/ifconfig eth0:1 192.168.137.50/24

3.master_ip_online_change

perl脚本

#!/usr/bin/env perl  
use strict;
use warnings FATAL =>\'all\';

use Getopt::Long;

my $vip = \'192.168.137.50/24\';  # Virtual IP  
my $key = "1";
my $ssh_start_vip = "/sbin/ifconfig eth0:$key $vip";
my $ssh_stop_vip = "/sbin/ifconfig eth0:$key down";
my $exit_code = 0;

my (
  $command,              $orig_master_is_new_slave, $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,
  $new_master_password,
);
GetOptions(
  \'command=s\'                => \\$command,
  \'orig_master_is_new_slave\' => \\$orig_master_is_new_slave,
  \'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,
);

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 $orig_master_user\\@$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 $new_master_user\\@$new_master_host \\" $ssh_start_vip \\"`;
}
# A simple system call that disable the VIP on the old_master  
sub stop_vip() {
`ssh $orig_master_user\\@$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";
}

shell脚本

#/bin/bash  
#source /root/.bash_profile  
  
vip=`echo \'192.168.137.50/24\'`  # Virtual IP  
key=`echo \'1\'`  
  
command=`echo "$1" | awk -F = \'{print $2}\'`  
orig_master_host=`echo "$2" | awk -F = \'{print $2}\'`  
new_master_host=`echo "$7" | awk -F = \'{print $2}\'`    
  
stop_vip=`echo "ssh root@$orig_master_host /sbin/ifconfig  eth0:$key  down"`  
start_vip=`echo "ssh root@$new_master_host /sbin/ifconfig  eth0:$key  $vip"`  
  
if [ $command = \'stop\' ]  
   then  
   echo -e "\\n\\n\\n***************************************************************\\n"  
   echo -e "Disabling the VIP - $vip on old master: $orig_master_host\\n"  
   $stop_vip  
   if [ $? -eq 0 ]  
      then  
      echo "Disabled the VIP successfully"  
   else  
      echo "Disabled the VIP failed"  
   fi  
   echo -e "***************************************************************\\n\\n\\n\\n"  
fi  
  
if [ $command = \'start\' -o $command = \'status\' ]  
   then  
   echo -e "\\n\\n\\n***************************************************************\\n"  
   echo -e "Enabling the VIP - $vip on new master: $new_master_host \\n"  
   $start_vip  
   if [ $? -eq 0 ]  
      then  
      echo "Enabled the VIP successfully"  
   else  
      echo "Enabled the VIP failed"  
   fi  
   echo -e "***************************************************************\\n\\n\\n\\n"  
fi

4.send_report

View Code

这里得先安装mutt,安装方法这里不做介绍

四、配置relay_log的清除方式（在每个Node上）

(1)所有Node的cnf配置文件加上

relay_log_purge=0

MHA在发生切换的过程中，从库的恢复过程中依赖于relay log的相关信息，所以这里要将relay log的自动清除设置为OFF，采用手动清除relay log的方式。

在默认情况下，从服务器上的中继日志会在SQL线程执行完毕后被自动删除。但是在MHA环境中，这些中继日志在恢复其他从服务器时可能会被用到，因此需要禁用中继日志的自动删除功能。定期清除中继日志需要考虑到复制延时的问题。在ext3的文件系统下，删除大的文件需要一定的时间，会导致严重的复制延时。为了避免复制延时，需要暂时为中继日志创建硬链接，因为在linux系统中通过硬链接删除大文件速度会很快。

提示：在mysql数据库中，删除大表时，通常也采用建立硬链接的方式

MHA节点中包含了pure_relay_logs命令工具，它可以为中继日志创建硬链接，执行SET GLOBAL relay_log_purge=1,等待几秒钟以便SQL线程切换到新的中继日志，再执行SET GLOBAL relay_log_purge=0。

pure_relay_logs脚本参数如下所示：

--user mysql                      用户名
--password mysql                  密码
--port                            端口号
--workdir                         指定创建relay log的硬链接的位置，默认是/var/tmp，由于系统不同分区创建硬链接文件会失败，故需要执行硬链接具体位置，成功执行脚本后，硬链接的中继日志文件被删除
--disable_relay_log_purge         默认情况下，如果relay_log_purge=1，脚本会什么都不清理，自动退出，通过设定这个参数，当relay_log_purge=1的情况下会将relay_log_purge设置为0。清理relay log之后，最后将参数设置为OFF。

(2)在每台slave Node上创建

vim /usr/local/mha/purge_relay_log.sh

#!/bin/bash
user=root
passwd=root  ####确保用户和密码能通过127.0.0.1登入
host=\'127.0.0.1\'
port=3306
work_dir=\'/mysql/data\'
purge=\'/usr/local/mha/bin/purge_relay_logs\'

$purge --user=$user --password=$passwd --host=$host --disable_relay_log_purge --port=$port --workdir=$work_dir >> /usr/local/mha/purge_relay_logs.log 2>&1

chmod u+x /usr/local/mha/purge_relay_log.sh

将脚本加入到os定时任务中

五、检测启动MHA

1.检查ssh配置

masterha_check_ssh  --conf=/usr/local/mha/ha1/ha1.cnf

[root@monitor ha1]# masterha_check_ssh --conf=/usr/local/mha/ha1/ha1.cnf
Thu Aug 25 14:53:30 2016 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Thu Aug 25 14:53:30 2016 - [info] Reading application default configurations from /usr/local/mha/ha1/ha1.cnf..
Thu Aug 25 14:53:30 2016 - [info] Reading server configurations from /usr/local/mha/ha1/ha1.cnf..
Thu Aug 25 14:53:30 2016 - [info] Starting SSH connection tests..
Thu Aug 25 14:53:35 2016 - [debug] 
Thu Aug 25 14:53:31 2016 - [debug]  Connecting via SSH from root@192.168.137.20(192.168.137.20:22) to root@192.168.137.10(192.168.137.10:22)..
Thu Aug 25 14:53:33 2016 - [debug]   ok.
Thu Aug 25 14:53:33 2016 - [debug]  Connecting via SSH from root@192.168.137.20(192.168.137.20:22) to root@192.168.137.30(192.168.137.30:22)..
Thu Aug 25 14:53:34 2016 - [debug]   ok.
Thu Aug 25 14:53:35 2016 - [debug] 
Thu Aug 25 14:53:31 2016 - [debug]  Connecting via SSH from root@192.168.137.30(192.168.137.30:22) to root@192.168.137.10(192.168.137.10:22)..
Thu Aug 25 14:53:33 2016 - [debug]   ok.
Thu Aug 25 14:53:33 2016 - [debug]  Connecting via SSH from root@192.168.137.30(192.168.137.30:22) to root@192.168.137.20(192.168.137.20:22)..
Thu Aug 25 14:53:34 2016 - [debug]   ok.
Thu Aug 25 14:53:36 2016 - [debug] 
Thu Aug 25 14:53:30 2016 - [debug]  Connecting via SSH from root@192.168.137.10(192.168.137.10:22) to root@192.168.137.20(192.168.137.20:22)..
Thu Aug 25 14:53:34 2016 - [debug]   ok.
Thu Aug 25 14:53:34 2016 - [debug]  Connecting via SSH from root@192.168.137.10(192.168.137.10:22) to root@192.168.137.30(192.168.137.30:22)..
Thu Aug 25 14:53:35 2016 - [debug]   ok.
Thu Aug 25 14:53:36 2016 - [info] All SSH connection tests passed successfully.

可以看到每个Node到其它的Node都是相通的。

2.检查整个复制环境

masterha_check_repl --conf=/usr/local/mha/ha1/ha1.cnf

View Code

--ignore_fail_on_start：当有slave 节点宕掉时，默认是启动不了的，加上 --ignore_fail_on_start 即使有节点宕掉也能启动MHA，加上该参数会忽略启动文件中配置ignore_fail=1的server

3.检查MHA Manager状态

masterha_check_status --conf=/usr/local/mha/ha1/ha1.cnf

由于mha还没有启动，所以这里检测是stopped

4.启动MHA

nohup masterha_manager --conf=/usr/local/mha/ha1/ha1.cnf --ignore_fail_on_start --ignore_last_failover < /dev/null > /usr/local/mha/ha1/start.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。这里暂时不使用该参数，因为发生使用该参数会将ha1.cnf配置文件搞乱。

--start_log:日志。

--ignore_last_failover：发生主从切换后，MHAmanager服务会自动停掉，且在manager_workdir目录下面生成文件app1.failover.complete，若要启动MHA，必须先删除该文件，该参数代表忽略上次MHA触发切换产生的文件，这里设置为-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。

--ignore_fail_on_start：当有slave 节点宕掉时，默认是启动不了的，加上 --ignore_fail_on_start 即使有节点宕掉也能启动MHA，加上该参数会忽略启动文件中配置ignore_fail=1的server。

(1)再次查看MHA状态是否正常：

[root@monitor ha1]# masterha_check_status --conf=/usr/local/mha/ha1/ha1.cnf
ha1 (pid:6371) is running(0:PING_OK), master:192.168.137.10
[root@monitor ha1]#

(2)查看启动日志

cat manager.log

Thu Aug 25 17:11:50 2016 - [info] 
192.168.137.10 (current master)
 +--192.168.137.20
 +--192.168.137.30

Thu Aug 25 17:11:50 2016 - [info] Checking master_ip_failover_script status:
Thu Aug 25 17:11:50 2016 - [info]   /usr/local/mha/ha1/fail_script/master_ip_failover --command=status --ssh_user=root --orig_master_host=192.168.137.10 --orig_master_ip=192.168.137.10 --orig_master_port=3306 


IN SCRIPT TEST====/sbin/ifconfig eth0:1 down==/sbin/ifconfig eth0:1 192.168.137.50/24===

Checking the Status of the script.. OK 
Thu Aug 25 17:11:50 2016 - [info]  OK.
Thu Aug 25 17:11:50 2016 - [warning] shutdown_script is not defined.
Thu Aug 25 17:11:50 2016 - [info] Set master ping interval 1 seconds.
Thu Aug 25 17:11:50 2016 - [info] Set secondary check script: /usr/local/mha/bin/masterha_secondary_check -s backup -s master --user=root --master_host=master --master_ip=192.168.137.10 --master_port=3306
Thu Aug 25 17:11:50 2016 - [info] Starting ping health check on 192.168.137.10(192.168.137.10:3306)..
Thu Aug 25 17:11:50 2016 - [info] Ping(SELECT) succeeded, waiting until MySQL doesn\'t respond..
[root@monitor ha1]#

(3)产生的文件

ha1.master_status.health：mha正常启动会产生该文件

manager.log：mha监控日志

start.log:mha启动时生成的日志

5.关闭MHA

masterha_stop --conf=/usr/local/mha/ha1/ha1.cnf

六、故障处理步骤

发生主从切换后，MHA服务会自动停掉

1.检查日志

检查故障处理的日志，确保故障正常转移。

cat /usr/local/mha/ha1/manager.log

2.处理故障master

处理故障的master，将其配置为从库chang到新的master，可以从manager.log找到change语句。

 grep "CHANGE MASTER TO MASTER" /usr/local/mha/ha1/manager.log | tail -1

Fri Aug 26 12:04:22 2016 - [info]  All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST=\'192.168.137.10\', MASTER_PORT=3306, MASTER_LOG_FILE=\'mysql-bin.000143\', MASTER_LOG_POS=22123166, MASTER_USER=\'repl\', MASTER_PASSWORD=\'xxx\';

注意：这里要确保slave的SQL_THREAD和IO_TRREAD正常，如果是配置半同步复制要确保半同步复制启动正常，可以执行"show status like \'%rpl_%\';",具体参考前面半同步复制的搭建。

3.修改ha1.cnf配置文件

需要修改"secondary_check_script"选项中的master_host、master_ip、master_port为新的master;如果两台电脑的配置都相同的话其它地方不用修改。

4.删除fail文件（非必需）

由于启动mha的时候加上了--ignore_last_failover参数，所以不删除failower生成的文件也能启动，否则需要删除failower生成的文件“ha1.failover.complete”。

rm -f /usr/local/mha/ha1/ha1.failover.complete

5.check检查

检查SSH配置
masterha_check_ssh --conf=/usr/local/mha/ha1/ha1.cnf
检查复制
masterha_check_repl --conf=/usr/local/mha/ha1/ha1.cnf 
检查状态
masterha_check_status --conf=/usr/local/mha/ha1/ha1.cnf

必需保证所有的检查都通过

6.启动MHA

nohup masterha_manager --conf=/usr/local/mha/ha1/ha1.cnf --ignore_fail_on_start  --ignore_last_failover < /dev/null > /usr/local/mha/ha1/start.log 2>&1 &

七、模拟Failover

1.自动failover

我这里是异步复制，137.20是当前的master，然后在137.20上执行并发插入，同时关闭137.10和137.30的IO线程，在137.20上压测一段时间，然后先开启137.30的IO线程，过几秒钟再开启137.10的IO线程；保证137.30的binlog比候选的137.10的binlog更新。

master 137.20（22497564）

candidate slave:137.10(pos=9857376)

new replay slave:137.30(pos=22461852)

Fri Aug 26 11:57:36 2016 - [warning] Got error on MySQL select ping: 2013 (Lost connection to MySQL server during query)
Fri Aug 26 11:57:36 2016 - [info] Executing SSH check script: save_binary_logs --command=test --start_pos=4 --binlog_dir=/mysql/log --output_file=/tmp/save_binary_logs_test --manager_version=0.55 --binlog_prefix=mysql-bin
Fri Aug 26 11:57:36 2016 - [info] Executing seconary network check script: /usr/local/mha/bin/masterha_secondary_check -s backup -s master --user=root --master_host=master --master_ip=192.168.137.10 --master_port=3306  --user=root  --master_host=192.168.137.20  --master_ip=192.168.137.20  --master_port=3306
Fri Aug 26 11:57:37 2016 - [warning] Got error on MySQL connect: 2003 (Can\'t connect to MySQL server on \'192.168.137.20\' (111))
Fri Aug 26 11:57:37 2016 - [warning] Connection failed 1 time(s)..
Fri Aug 26 11:57:38 2016 - [warning] Got error on MySQL connect: 2003 (Can\'t connect to MySQL server on \'192.168.137.20\' (111))
Fri Aug 26 11:57:38 2016 - [warning] Connection failed 2 time(s)..
Fri Aug 26 11:57:38 2016 - [info] HealthCheck: SSH to 192.168.137.20 is reachable.
Monitoring server backup is reachable, Master is not reachable from backup. OK.
Fri Aug 26 11:57:39 2016 - [warning] Got error on MySQL connect: 2003 (Can\'t connect to MySQL server on \'192.168.137.20\' (111))
Fri Aug 26 11:57:39 2016 - [warning] Connection failed 3 time(s)..
Monitoring server master is reachable, Master is not reachable from master. OK.
Fri Aug 26 11:57:41 2016 - [info] Master is not reachable from all other monitoring servers. Failover should start.
Fri Aug 26 11:57:41 2016 - [warning] Master is not reachable from health checker!
Fri Aug 26 11:57:41 2016 - [warning] Master 192.168.137.20(192.168.137.20:3306) is not reachable!
Fri Aug 26 11:57:41 2016 - [warning] SSH is reachable.
Fri Aug 26 11:57:41 2016 - [info] Connecting to a master server failed. Reading configuration file /etc/masterha_default.cnf and /usr/local/mha/ha1/ha1.cnf again, and trying to connect to all servers to check server status..
Fri Aug 26 11:57:41 2016 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Fri Aug 26 11:57:41 2016 - [info] Reading application default configurations from /usr/local/mha/ha1/ha1.cnf..
Fri Aug 26 11:57:41 2016 - [info] Reading server configurations from /usr/local/mha/ha1/ha1.cnf..
Fri Aug 26 11:57:42 2016 - [info] Dead Servers:
Fri Aug 26 11:57:42 2016 - [info]   192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:42 2016 - [info] Alive Servers:
Fri Aug 26 11:57:42 2016 - [info]   192.168.137.10(192.168.137.10:3306)
Fri Aug 26 11:57:42 2016 - [info]   192.168.137.30(192.168.137.30:3306)
Fri Aug 26 11:57:42 2016 - [info] Alive Slaves:
Fri Aug 26 11:57:42 2016 - [info]   192.168.137.10(192.168.137.10:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:42 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:42 2016 - [info]     Primary candidate for the new Master (candidate_master is set)
Fri Aug 26 11:57:42 2016 - [info]   192.168.137.30(192.168.137.30:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:42 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:42 2016 - [info]     Not candidate for the new Master (no_master is set)
Fri Aug 26 11:57:42 2016 - [info] Checking slave configurations..
Fri Aug 26 11:57:42 2016 - [info]  read_only=1 is not set on slave 192.168.137.10(192.168.137.10:3306).
Fri Aug 26 11:57:42 2016 - [info] Checking replication filtering settings..
Fri Aug 26 11:57:42 2016 - [info]  Replication filtering check ok.
Fri Aug 26 11:57:42 2016 - [info] Master is down!
Fri Aug 26 11:57:42 2016 - [info] Terminating monitoring script.
Fri Aug 26 11:57:42 2016 - [info] Got exit code 20 (Master dead).
Fri Aug 26 11:57:42 2016 - [info] MHA::MasterFailover version 0.55.
Fri Aug 26 11:57:42 2016 - [info] Starting master failover.
Fri Aug 26 11:57:42 2016 - [info] 
Fri Aug 26 11:57:42 2016 - [info] * Phase 1: Configuration Check Phase..
Fri Aug 26 11:57:42 2016 - [info] 
Fri Aug 26 11:57:44 2016 - [info] Dead Servers:
Fri Aug 26 11:57:44 2016 - [info]   192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:44 2016 - [info] Checking master reachability via mysql(double check)..
Fri Aug 26 11:57:44 2016 - [info]  ok.
Fri Aug 26 11:57:44 2016 - [info] Alive Servers:
Fri Aug 26 11:57:44 2016 - [info]   192.168.137.10(192.168.137.10:3306)
Fri Aug 26 11:57:44 2016 - [info]   192.168.137.30(192.168.137.30:3306)
Fri Aug 26 11:57:44 2016 - [info] Alive Slaves:
Fri Aug 26 11:57:44 2016 - [info]   192.168.137.10(192.168.137.10:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:44 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:44 2016 - [info]     Primary candidate for the new Master (candidate_master is set)
Fri Aug 26 11:57:44 2016 - [info]   192.168.137.30(192.168.137.30:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:44 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:44 2016 - [info]     Not candidate for the new Master (no_master is set)
Fri Aug 26 11:57:44 2016 - [info] ** Phase 1: Configuration Check Phase completed.
Fri Aug 26 11:57:44 2016 - [info] 
Fri Aug 26 11:57:44 2016 - [info] * Phase 2: Dead Master Shutdown Phase..
Fri Aug 26 11:57:44 2016 - [info] 
Fri Aug 26 11:57:44 2016 - [info] Forcing shutdown so that applications never connect to the current master..
Fri Aug 26 11:57:44 2016 - [info] Executing master IP deactivatation script:
Fri Aug 26 11:57:44 2016 - [info]   /usr/local/mha/ha1/fail_script/master_ip_failover --orig_master_host=192.168.137.20 --orig_master_ip=192.168.137.20 --orig_master_port=3306 --command=stopssh --ssh_user=root  


IN SCRIPT TEST====/sbin/ifconfig eth0:1 down==/sbin/ifconfig eth0:1 192.168.137.50/24===

Disabling the VIP on old master: 192.168.137.20 
Fri Aug 26 11:57:45 2016 - [info]  done.
Fri Aug 26 11:57:45 2016 - [warning] shutdown_script is not set. Skipping explicit shutting down of the dead master.
Fri Aug 26 11:57:45 2016 - [info] * Phase 2: Dead Master Shutdown Phase completed.
Fri Aug 26 11:57:45 2016 - [info] 
Fri Aug 26 11:57:45 2016 - [info] * Phase 3: Master Recovery Phase..
Fri Aug 26 11:57:45 2016 - [info] 
Fri Aug 26 11:57:45 2016 - [info] * Phase 3.1: Getting Latest Slaves Phase..
Fri Aug 26 11:57:45 2016 - [info] 
Fri Aug 26 11:57:45 2016 - [info] The latest binary log file/position on all slaves is mysql-bin.000074:22461852
Fri Aug 26 11:57:45 2016 - [info] Latest slaves (Slaves that received relay log files to the latest):
Fri Aug 26 11:57:45 2016 - [info]   192.168.137.30(192.168.137.30:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:45 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:45 2016 - [info]     Not candidate for the new Master (no_master is set)
Fri Aug 26 11:57:45 2016 - [info] The oldest binary log file/position on all slaves is mysql-bin.000074:9857376
Fri Aug 26 11:57:45 2016 - [info] Oldest slaves:
Fri Aug 26 11:57:45 2016 - [info]   192.168.137.10(192.168.137.10:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:45 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:45 2016 - [info]     Primary candidate for the new Master (candidate_master is set)
Fri Aug 26 11:57:45 2016 - [info] 
Fri Aug 26 11:57:45 2016 - [info] * Phase 3.2: Saving Dead Master\'s Binlog Phase..
Fri Aug 26 11:57:45 2016 - [info] 
Fri Aug 26 11:57:46 2016 - [info] Fetching dead master\'s binary logs..
Fri Aug 26 11:57:46 2016 - [info] Executing command on the dead master 192.168.137.20(192.168.137.20:3306): save_binary_logs --command=save --start_file=mysql-bin.000074  --start_pos=22461852 --binlog_dir=/mysql/log --output_file=/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.55
  Creating /tmp if not exists..    ok.
 Concat binary/relay logs from mysql-bin.000074 pos 22461852 to mysql-bin.000074 EOF into /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog ..
  Dumping binlog format description event, from position 0 to 120.. ok.
  Dumping effective binlog data from /mysql/log/mysql-bin.000074 position 22461852 to tail(22497564).. ok.
 Concat succeeded.
Fri Aug 26 11:57:49 2016 - [info] scp from root@192.168.137.20:/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog to local:/usr/local/mha/ha1/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog succeeded.
Fri Aug 26 11:57:52 2016 - [info] HealthCheck: SSH to 192.168.137.10 is reachable.
Fri Aug 26 11:57:55 2016 - [info] HealthCheck: SSH to 192.168.137.30 is reachable.
Fri Aug 26 11:57:55 2016 - [info] 
Fri Aug 26 11:57:55 2016 - [info] * Phase 3.3: Determining New Master Phase..
Fri Aug 26 11:57:55 2016 - [info] 
Fri Aug 26 11:57:55 2016 - [info] Finding the latest slave that has all relay logs for recovering other slaves..
Fri Aug 26 11:57:55 2016 - [info] Checking whether 192.168.137.30 has relay logs from the oldest position..
Fri Aug 26 11:57:55 2016 - [info] Executing command: apply_diff_relay_logs --command=find --latest_mlf=mysql-bin.000074 --latest_rmlp=22461852 --target_mlf=mysql-bin.000074 --target_rmlp=9857376 --server_id=30 --workdir=/tmp --timestamp=20160826115742 --manager_version=0.55 --relay_log_info=/mysql/data/relay-log.info  --relay_dir=/mysql/data/  :
    Opening /mysql/data/relay-log.info ... ok.
    Relay log found at /mysql/data, up to mysql-relay-bin.000003
 Fast relay log position search succeeded.
 Target relay log file/position found. start_file:mysql-relay-bin.000003, start_pos:9857539.
Target relay log FOUND!
Fri Aug 26 11:57:56 2016 - [info] OK. 192.168.137.30 has all relay logs.
Fri Aug 26 11:57:56 2016 - [info] Searching new master from slaves..
Fri Aug 26 11:57:56 2016 - [info]  Candidate masters from the configuration file:
Fri Aug 26 11:57:56 2016 - [info]   192.168.137.10(192.168.137.10:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:56 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:56 2016 - [info]     Primary candidate for the new Master (candidate_master is set)
Fri Aug 26 11:57:56 2016 - [info]  Non-candidate masters:
Fri Aug 26 11:57:56 2016 - [info]   192.168.137.30(192.168.137.30:3306)  Version=5.6.15-log (oldest major version between slaves) log-bin:enabled
Fri Aug 26 11:57:56 2016 - [info]     Replicating from 192.168.137.20(192.168.137.20:3306)
Fri Aug 26 11:57:56 2016 - [info]     Not candidate for the new Master (no_master is set)
Fri Aug 26 11:57:56 2016 - [info]  Searching from candidate_master slaves which have received the latest relay log events..
Fri Aug 26 11:57:56 2016 - [info]   Not found.
Fri Aug 26 11:57:56 2016 - [info]  Searching from all candidate_master slaves..
Fri Aug 26 11:57:56 2016 - [info] New master is 192.168.137.10(192.168.137.10:3306)
Fri Aug 26 11:57:56 2016 - [info] Starting master failover..
Fri Aug 26 11:57:56 2016 - [info] 
From:
192.168.137.20 (current master)
 +--192.168.137.10
 +--192.168.137.30

To:
192.168.137.10 (new master)
 +--192.168.137.30
Fri Aug 26 11:57:56 2016 - [info] 
Fri Aug 26 11:57:56 2016 - [info] * Phase 3.3: New Master Diff Log Generation Phase..
Fri Aug 26 11:57:56 2016 - [info] 
Fri Aug 26 11:57:56 2016 - [info] Server 192.168.137.10 received relay logs up to: mysql-bin.000074:9857376
Fri Aug 26 11:57:56 2016 - [info] Need to get diffs from the latest slave(192.168.137.30) up to: mysql-bin.000074:22461852 (using the latest slave\'s relay logs)
Fri Aug 26 11:57:56 2016 - [info] Connecting to the latest slave host 192.168.137.30, generating diff relay log files..
Fri Aug 26 11:57:56 2016 - [info] Executing command: apply_diff_relay_logs --command=generate_and_send --scp_user=root --scp_host=192.168.137.10 --latest_mlf=mysql-bin.000074 --latest_rmlp=22461852 --target_mlf=mysql-bin.000074 --target_rmlp=9857376 --server_id=30 --diff_file_readtolatest=/tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog --workdir=/tmp --timestamp=20160826115742 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.55 --relay_log_info=/mysql/data/relay-log.info  --relay_dir=/mysql/data/ 
Fri Aug 26 11:58:02 2016 - [info] 
    Opening /mysql/data/relay-log.info ... ok.
    Relay log found at /mysql/data, up to mysql-relay-bin.000003
 Fast relay log position search succeeded.
 Target relay log file/position found. start_file:mysql-relay-bin.000003, start_pos:9857539.
 Concat binary/relay logs from mysql-relay-bin.000003 pos 9857539 to mysql-relay-bin.000003 EOF into /tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog ..
  Dumping binlog format description event, from position 0 to 283.. ok.
  Dumping effective binlog data from /mysql/data/mysql-relay-bin.000003 position 9857539 to tail(22462015).. ok.
 Concat succeeded.
 Generating diff relay log succeeded. Saved at /tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog .
 scp slave:/tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog to root@192.168.137.10(22) succeeded.
Fri Aug 26 11:58:02 2016 - [info]  Generating diff files succeeded.
Fri Aug 26 11:58:02 2016 - [info] Sending binlog..
Fri Aug 26 11:58:04 2016 - [info] scp from local:/usr/local/mha/ha1/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog to root@192.168.137.10:/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog succeeded.
Fri Aug 26 11:58:04 2016 - [info] 
Fri Aug 26 11:58:04 2016 - [info] * Phase 3.4: Master Log Apply Phase..
Fri Aug 26 11:58:04 2016 - [info] 
Fri Aug 26 11:58:04 2016 - [info] *NOTICE: If any error happens from this phase, manual recovery is needed.
Fri Aug 26 11:58:04 2016 - [info] Starting recovery on 192.168.137.10(192.168.137.10:3306)..
Fri Aug 26 11:58:04 2016 - [info]  Generating diffs succeeded.
Fri Aug 26 11:58:04 2016 - [info] Waiting until all relay logs are applied.
Fri Aug 26 12:00:06 2016 - [info]  done.
Fri Aug 26 12:00:06 2016 - [info] Getting slave status..
Fri Aug 26 12:00:06 2016 - [info] This slave(192.168.137.10)\'s Exec_Master_Log_Pos equals to Read_Master_Log_Pos(mysql-bin.000074:9857376). No need to recover from Exec_Master_Log_Pos.
Fri Aug 26 12:00:06 2016 - [info] Connecting to the target slave host 192.168.137.10, running recover script..
Fri Aug 26 12:00:06 2016 - [info] Executing command: apply_diff_relay_logs --command=apply --slave_user=\'root\' --slave_host=192.168.137.10 --slave_ip=192.168.137.10  --slave_port=3306 --apply_files=/tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog,/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog --workdir=/tmp --target_version=5.6.15-log --timestamp=20160826115742 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.55 --slave_pass=xxx
Fri Aug 26 12:04:22 2016 - [info] 
 Concat all apply files to /tmp/total_binlog_for_192.168.137.10_3306.20160826115742.binlog ..
 Copying the first binlog file /tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog to /tmp/total_binlog_for_192.168.137.10_3306.20160826115742.binlog.. ok.
  Dumping binlog head events (rotate events), skipping format description events from /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog.. dumped up to pos 120. ok.
 /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog has effective binlog events from pos 120.
  Dumping effective binlog data from /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog position 120 to tail(35832).. ok.
 Concat succeeded.
All apply target binary logs are concatinated at /tmp/total_binlog_for_192.168.137.10_3306.20160826115742.binlog .
MySQL client version is 5.6.15. Using --binary-mode.
Applying differential binary/relay log files /tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog,/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog on 192.168.137.10:3306. This may take long time...
Applying log files succeeded.
Fri Aug 26 12:04:22 2016 - [info]  All relay logs were successfully applied.
Fri Aug 26 12:04:22 2016 - [info] Getting new master\'s binlog name and position..
Fri Aug 26 12:04:22 2016 - [info]  mysql-bin.000143:22123166
Fri Aug 26 12:04:22 2016 - [info]  All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST=\'192.168.137.10\', MASTER_PORT=3306, MASTER_LOG_FILE=\'mysql-bin.000143\', MASTER_LOG_POS=22123166, MASTER_USER=\'repl\', MASTER_PASSWORD=\'xxx\';
Fri Aug 26 12:04:22 2016 - [info] Executing master IP activate script:
Fri Aug 26 12:04:22 2016 - [info]   /usr/local/mha/ha1/fail_script/master_ip_failover --command=start --ssh_user=root --orig_master_host=192.168.137.20 --orig_master_ip=192.168.137.20 --orig_master_port=3306 --new_master_host=192.168.137.10 --new_master_ip=192.168.137.10 --new_master_port=3306 --new_master_user=\'root\' --new_master_password=\'root\'  


IN SCRIPT TEST====/sbin/ifconfig eth0:1 down==/sbin/ifconfig eth0:1 192.168.137.50/24===

Enabling the VIP - 192.168.137.50/24 on the new master - 192.168.137.10 
Fri Aug 26 12:04:25 2016 - [info]  OK.
Fri Aug 26 12:04:25 2016 - [info] ** Finished master recovery successfully.
Fri Aug 26 12:04:25 2016 - [info] * Phase 3: Master Recovery Phase completed.
Fri Aug 26 12:04:25 2016 - [info] 
Fri Aug 26 12:04:25 2016 - [info] * Phase 4: Slaves Recovery Phase..
Fri Aug 26 12:04:25 2016 - [info] 
Fri Aug 26 12:04:25 2016 - [info] * Phase 4.1: Starting Parallel Slave Diff Log Generation Phase..
Fri Aug 26 12:04:25 2016 - [info] 
Fri Aug 26 12:04:25 2016 - [info] -- Slave diff file generation on host 192.168.137.30(192.168.137.30:3306) started, pid: 5029. Check tmp log /usr/local/mha/ha1/192.168.137.30_3306_20160826115742.log if it takes time..
Fri Aug 26 12:04:26 2016 - [info] 
Fri Aug 26 12:04:26 2016 - [info] Log messages from 192.168.137.30 ...
Fri Aug 26 12:04:26 2016 - [info] 
Fri Aug 26 12:04:25 2016 - [info]  This server has all relay logs. No need to generate diff files from the latest slave.
Fri Aug 26 12:04:26 2016 - [info] End of log messages from 192.168.137.30.
Fri Aug 26 12:04:26 2016 - [info] -- 192.168.137.30(192.168.137.30:3306) has the latest relay log events.
Fri Aug 26 12:04:26 2016 - [info] Generating relay diff files from the latest slave succeeded.
Fri Aug 26 12:04:26 2016 - [info] 
Fri Aug 26 12:04:26 2016 - [info] * Phase 4.2: Starting Parallel Slave Log Apply Phase..
Fri Aug 26 12:04:26 2016 - [info] 
Fri Aug 26 12:04:26 2016 - [info] -- Slave recovery on host 192.168.137.30(192.168.137.30:3306) started, pid: 5031. Check tmp log /usr/local/mha/ha1/192.168.137.30_3306_20160826115742.log if it takes time..
Fri Aug 26 12:04:32 2016 - [info] 
Fri Aug 26 12:04:32 2016 - [info] Log messages from 192.168.137.30 ...
Fri Aug 26 12:04:32 2016 - [info] 
Fri Aug 26 12:04:26 2016 - [info] Sending binlog..
Fri Aug 26 12:04:28 2016 - [info] scp from local:/usr/local/mha/ha1/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog to root@192.168.137.30:/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog succeeded.
Fri Aug 26 12:04:28 2016 - [info] Starting recovery on 192.168.137.30(192.168.137.30:3306)..
Fri Aug 26 12:04:28 2016 - [info]  Generating diffs succeeded.
Fri Aug 26 12:04:28 2016 - [info] Waiting until all relay logs are applied.
Fri Aug 26 12:04:28 2016 - [info]  done.
Fri Aug 26 12:04:28 2016 - [info] Getting slave status..
Fri Aug 26 12:04:28 2016 - [info] This slave(192.168.137.30)\'s Exec_Master_Log_Pos equals to Read_Master_Log_Pos(mysql-bin.000074:22461852). No need to recover from Exec_Master_Log_Pos.
Fri Aug 26 12:04:28 2016 - [info] Connecting to the target slave host 192.168.137.30, running recover script..
Fri Aug 26 12:04:28 2016 - [info] Executing command: apply_diff_relay_logs --command=apply --slave_user=\'root\' --slave_host=192.168.137.30 --slave_ip=192.168.137.30  --slave_port=3306 --apply_files=/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog --workdir=/tmp --target_version=5.6.15-log --timestamp=20160826115742 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.55 --slave_pass=xxx
Fri Aug 26 12:04:30 2016 - [info] 
MySQL client version is 5.6.15. Using --binary-mode.
Applying differential binary/relay log files /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog on 192.168.137.30:3306. This may take long time...
Applying log files succeeded.
Fri Aug 26 12:04:30 2016 - [info]  All relay logs were successfully applied.
Fri Aug 26 12:04:30 2016 - [info]  Resetting slave 192.168.137.30(192.168.137.30:3306) and starting replication from the new master 192.168.137.10(192.168.137.10:3306)..
Fri Aug 26 12:04:31 2016 - [info]  Executed CHANGE MASTER.
Fri Aug 26 12:04:31 2016 - [info]  Slave started.
Fri Aug 26 12:04:32 2016 - [info] End of log messages from 192.168.137.30.
Fri Aug 26 12:04:32 2016 - [info] -- Slave recovery on host 192.168.137.30(192.168.137.30:3306) succeeded.
Fri Aug 26 12:04:32 2016 - [info] All new slave servers recovered successfully.
Fri Aug 26 12:04:32 2016 - [info] 
Fri Aug 26 12:04:32 2016 - [info] * Phase 5: New master cleanup phase..
Fri Aug 26 12:04:32 2016 - [info] 
Fri Aug 26 12:04:32 2016 - [info] Resetting slave info on the new master..
Fri Aug 26 12:04:32 2016 - [info]  192.168.137.10: Resetting slave info succeeded.
Fri Aug 26 12:04:32 2016 - [info] Master failover to 192.168.137.10(192.168.137.10:3306) completed successfully.
Fri Aug 26 12:04:32 2016 - [info] 

----- Failover Report -----

ha1: MySQL Master failover 192.168.137.20 to 192.168.137.10 succeeded

Master 192.168.137.20 is down!

Check MHA Manager logs at monitor:/usr/local/mha/ha1/manager.log for details.

Started automated(non-interactive) failover.
Invalidated master IP address on 192.168.137.20.
The latest slave 192.168.137.30(192.168.137.30:3306) has all relay logs for recovery.
Selected 192.168.137.10 as a new master.
192.168.137.10: OK: Applying all logs succeeded.
192.168.137.10: OK: Activated master IP address.
192.168.137.30: This host has the latest relay log events.
Generating relay diff files from the latest slave succeeded.
192.168.137.30: OK: Applying all logs succeeded. Slave started, replicating from 192.168.137.10.
192.168.137.10: Resetting slave info succeeded.
Master failover to 192.168.137.10(192.168.137.10:3306) completed successfully.

说明：用红色标记了一些主要的处理过程，亮色加粗标记了每个步骤总共5个步骤

Failover步骤如下：

1.fail判断,分别判断dead master的mysql(Ping(SELECT))和ssh分别到达情况（之间会调用masterha_secondary_check脚本）→dead master处理阶段

2.配置文件检查，会检查整个集群配置文件配置（分别确定dead server,候选的master和所有的server的配置情况以及配置是否满足条件）→dead master处理阶段

3.宕机的master处理，包括虚拟ip摘除操作，主机关机操作（这里暂时没有配置关机操作）→dead master处理阶段

/usr/local/mha/ha1/fail_script/master_ip_failover --orig_master_host=192.168.137.20 --orig_master_ip=192.168.137.20 --orig_master_port=3306 --command=stopssh --ssh_user=root

4.找到含有最新relay log的slave(同时找到最旧的binlog的slave的position), 分别判断是否是候选的slave→new master还原阶段

5.保存dead master(137.20)和最新slave(137.30)相差的relay log保存在dead master的/tmp目录下（根据配置文件配置的remote_workdir）,然后确定这部分差异binlog（saved_master_binlog_）是否有效,也就是dead master和最新的slave之间是否存在binlog差异，存在差异则将生成的这个差异binlog拷贝到mha的workdir(137.40)下→new master还原阶段

Fri Aug 26 11:57:46 2016 - [info] Executing command on the dead master 192.168.137.20(192.168.137.20:3306): save_binary_logs --command=save --start_file=mysql-bin.000074  --start_pos=22461852 --binlog_dir=/mysql/log --output_file=/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.55
  Creating /tmp if not exists..    ok.
 Concat binary/relay logs from mysql-bin.000074 pos 22461852 to mysql-bin.000074 EOF into /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog ..
  Dumping binlog format description event, from position 0 to 120.. ok.
  Dumping effective binlog data from /mysql/log/mysql-bin.000074 position 22461852 to tail(22497564).. ok.
 Concat succeeded.
Fri Aug 26 11:57:49 2016 - [info] scp from root@192.168.137.20:/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog to local:/usr/local/mha/ha1/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog succeeded.

7.确定新的master，并检查最新slave(30)的relay log是否可以用来还原其他的slave→new master还原阶段

8.生成最新slave(137.30)和new master(137.10)之间的差异relay log(在最新relay log的slave的/tmp下生成和其它slave差异的binlog，是二者的“Read_Master_Log_Pos”的差，取名为“relay_from_read_to_latest_后面紧接的是目标slave的ip”)，然后cp到目标（new master）的slave的/tmp下，同时将mha workdir下刚才保存的"saved_master_binlog_"(如果存在)文件拷贝到new master的/tmp下→new master还原阶段

Fri Aug 26 11:57:56 2016 - [info] Connecting to the latest slave host 192.168.137.30, generating diff relay log files..
Fri Aug 26 11:57:56 2016 - [info] Executing command: apply_diff_relay_logs --command=generate_and_send --scp_user=root --scp_host=192.168.137.10 --latest_mlf=mysql-bin.000074 --latest_rmlp=22461852 --target_mlf=mysql-bin.000074 --target_rmlp=9857376 --server_id=30 --diff_file_readtolatest=/tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog --workdir=/tmp --timestamp=20160826115742 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.55 --relay_log_info=/mysql/data/relay-log.info  --relay_dir=/mysql/data/ 
Fri Aug 26 11:58:02 2016 - [info] 
    Opening /mysql/data/relay-log.info ... ok.
    Relay log found at /mysql/data, up to mysql-relay-bin.000003
 Fast relay log position search succeeded.
 Target relay log file/position found. start_file:mysql-relay-bin.000003, start_pos:9857539.
 Concat binary/relay logs from mysql-relay-bin.000003 pos 9857539 to mysql-relay-bin.000003 EOF into /tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog ..
  Dumping binlog format description event, from position 0 to 283.. ok.
  Dumping effective binlog data from /mysql/data/mysql-relay-bin.000003 position 9857539 to tail(22462015).. ok.
 Concat succeeded.
 Generating diff relay log succeeded. Saved at /tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog .
 scp slave:/tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog to root@192.168.137.10(22) succeeded.

9.new master应用差异的relay log（首先会判断该salve原本Read_Master_Log_Pos”和“Exec_Master_Log_Pos是否相等，由于不是半同步复制所以slave虽然读到了该pos但是但是由于复制是异步的所有还得等待master定时发送binlog到slave，如果这中间master故障了就会导致二者的不一致)，如果不相等会在该slave执行save_binary_logs命令保存之间差异的relay log取名为“relay_from_exec_to_read_后面紧接的是自身的ip”；然后应用"relay_from_read_to_latest_、saved_master_binlog_、relay_from_exec_to_read_"这三个差异的relay log,同时将这三个文件的内容合并生成一个新的binlog文件“total_binlog_for_”→new master还原阶段

Fri Aug 26 12:00:06 2016 - [info] This slave(192.168.137.10)\'s Exec_Master_Log_Pos equals to Read_Master_Log_Pos(mysql-bin.000074:9857376). No need to recover from Exec_Master_Log_Pos. Fri Aug 26 12:00:06 2016 - [info] Connecting to the target slave host 192.168.137.10, running recover script.. Fri Aug 26 12:00:06 2016 - [info] Executing command: apply_diff_relay_logs --command=apply --slave_user=\'root\' --slave_host=192.168.137.10 --slave_ip=192.168.137.10 --slave_port=3306 --apply_files=/tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog,/tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog --workdir=/tmp --target_version=5.6.15-log --timestamp=20160826115742 --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.55 --slave_pass=xxx Fri Aug 26 12:04:22 2016 - [info] Concat all apply files to /tmp/total_binlog_for_192.168.137.10_3306.20160826115742.binlog .. Copying the first binlog file /tmp/relay_from_read_to_latest_192.168.137.10_3306_20160826115742.binlog to /tmp/total_binlog_for_192.168.137.10_3306.20160826115742.binlog.. ok. Dumping binlog head events (rotate events), skipping format description events from /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog.. dumped up to pos 120. ok. /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog has effective binlog events from pos 120. Dumping effective binlog data from /tmp/saved_master_binlog_from_192.168.137.20_3306_20160826115742.binlog position 120 to tail(35832).. ok. Concat succeeded. All apply target binary logs are concatinated at /tmp/total_binlog_for_192.168.137.10_3306.20160826115742.binlog . MySQL client version is 5.6.15. Using --binary-mode. Applying differential binary/relay log files /tmp/relay_from_read_to_latest_192.168.137.10_3306_2016

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