MHA+keepalive高可用环境搭建

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MHA（Master HighAvailability）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。

该软件由两部分组成：MHA Manager（管理节点）和MHA Node（数据节点）。

MHA Node运行在每台MySQL服务器上，MHAManager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。

实验环境

10.192.203.201, 10.192.203.101上面安装了keepalive,vip是108

实验步骤

1 修改/etc/hosts

在mha管理节点和数据节点所在服务器上添加这些服务器ip和主机名对应关系。

如：

cat /etc/hosts

10.192.203.201 pc2

10.192.203.101 slave1

10.192.203.102 PC

2 Mysql主从复制环境搭建

搭建过程略，可以参考参考：http://blog.csdn.net/yabingshi_tech/article/details/45192599。

要确保两个从库设置read_only。

要确保master和备选master为主主互备模式，否则后面配置过程有可能会发生错误。

3 配置主机信任关系

在所有节点生成密码文件，然后将其拷贝到本机及其他服务器上，这里以10.192.203.201为例：

# ssh-keygen

# ssh-copy-id root@10.192.203.201

# ssh-copy-id root@10.192.203.101

# ssh-copy-id root@10.192.203.102

然后ssh验证下，是否可以免密码登录。

4 安装MHA

点击这里进行下载：

http://download.csdn.net/download/yabignshi/8974251

http://download.csdn.net/detail/yabignshi/8974265

在所有数据节点上安装：

yum install perl-DBD-MySQL -y

rpm -ivh mha4mysql-node-0.56-0.el6.noarch.rpm

安装完成后会在/usr/bin目录下生成以下脚本文件(这些工具通常由MHAManager的脚本触发，无需人为操作)：

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）

在管理节点上安装：

yum install perl-DBD-MySQL -y（由于本实验环境管理节点和数据节点部署在了同一台服务器上，所以这里不用重复安装）

yum install perl-Config-Tiny -y

yum install epel-release -y

yum install perl-Log-Dispatch -y

yum install perl-Parallel-ForkManager -y

rpm -ivh mha4mysql-node-0.56-0.el6.noarch.rpm（由于本实验环境管理节点和数据节点部署在了同一台服务器上，所以这里不用重复安装）

rpm -ivh mha4mysql-manager-0.56-0.el6.noarch.rpm

安装完成后会在/usr/bin目录下生成以下脚本文件:

-rwxr-xr-x. 1 root      root       1995 Apr  1  2014 masterha_check_repl-rwxr-xr-x. 1 root      root        1779 Apr 1  2014 masterha_check_ssh-rwxr-xr-x. 1 root      root       1865 Apr  1  2014 masterha_check_status-rwxr-xr-x. 1 root      root        3201 Apr 1  2014 masterha_conf_host-rwxr-xr-x. 1 root      root        2517 Apr 1  2014 masterha_manager-rwxr-xr-x. 1 root      root        2165 Apr 1  2014 masterha_master_monitor-rwxr-xr-x. 1 root      root        2373 Apr 1  2014 masterha_master_switch-rwxr-xr-x. 1 root      root        5171 Apr 1  2014 masterha_secondary_check-rwxr-xr-x. 1 root      root        1739 Apr 1  2014 masterha_stop-rwxr-xr-x. 1 root      root       4807 Apr  1  2014 filter_mysqlbinlog-rwxr-xr-x. 1 root      root       7525 Apr  1  2014 save_binary_logs-rwxr-xr-x. 1 root      root       8261 Apr  1  2014 purge_relay_logs-rwxr-xr-x. 1 root      root      16367 Apr  1  2014 apply_diff_relay_logs

5 安装配置keepalive

5.1 安装keepalive

在master和备选master上安装keepalive:

yum install -y popt-develcd /usr/local/srcwgethttp://www.keepalived.org/software/keepalived-1.2.2.tar.gztar zxvf keepalived-1.2.2.tar.gzcd keepalived-1.2.2./configure --prefix=/makemake install

5.2 修改配置文件

vi/etc/keepalived/keepalived.conf

master和备选master配置文件内容相同。

#ConfigurationFile for keepalivedglobal_defs {notification_email {                        ######定义接受邮件的邮箱 wangjj@hrloo.com       } notification_email_from jiankong@staff.tuge.com    ######定义发送邮件的邮箱 smtp_server mail.tuge.com smtp_connect_timeout 10}vrrp_instance vrrptest {                 ######定义vrrptest实例       state BACKUP              ######服务器状态 interface eth0                     ######使用的接口       virtual_router_id 51               ######虚拟路由的标志，一组lvs的虚拟路由标识必须相同，这样才能切换       priority 150                       ######服务启动优先级，值越大，优先级越高，BACKUP 不能大于MASTER       advert_int 1                        ######服务器之间的存活检查时间authentication {       auth_type PASS                     ######认证类型       auth_pass ufsoft       ######认证密码，一组lvs 服务器的认证密码必须一致}virtual_ipaddress {                         ######虚拟IP地址        10.192.203.108}}

这里master服务器的state不配置成MASTER，且配置的优先级一样，是期望在master宕机后再恢复时，不主动将MASTER状态抢过来，避免MySQL服务的波动。

这里没有配置vrrp_script，在后面会让mha实现vip的自动漂移。

5.3 vi /etc/sysconfig/iptables

#注意，在两台机器上都要修改。

添加：

-A INPUT-d 10.192.203.108/32 -j ACCEPT

-A INPUT-d 224.0.0.18 -j ACCEPT #添加VRRP通讯支持

注意：第一行中的10.192.203.108需要改成你自己的vip。

serviceiptables restart

5.4 启动keepalive

service keepalived start

分别执行ip addr命令，可以在其中一台机器上看到虚拟IP

5.5 测试

停止master服务器keepalived，检查VIP是否切换到备选master服务器（用ip addr命令验证即可）；

6 配置Mha

6.1 添加管理账号

#在数据节点上执行以下操作

grant all privileges on *.* TO mha@'10.192.%' IDENTIFIED BY 'test';

flush privileges;

6.2 配置/etc/mha/app1.cnf

#只在管理端做

mkdir /etc/mha

mkdir -p /var/log/mha/app1

vi /etc/mha/app1.cnf

添加：

[server default]manager_log=/var/log/mha/app1/manager.logmanager_workdir=/var/log/mha/app1.logmaster_binlog_dir=/data/mysql/datamaster_ip_failover_script= /usr/bin/master_ip_failover     master_ip_online_change_script=/usr/bin/master_ip_online_changereport_script=/usr/bin/send_report user=mhapassword=testping_interval=2repl_password=beijingrepl_user=rep_userssh_user=root [server1]hostname=10.192.203.201port=3306 [server2]candidate_master=1check_repl_delay=0hostname=10.192.203.101port=3306 [server3]hostname=10.192.203.102port=3306

在server default中的配置，是三台数据节点共同的配置，也可以放到具体的server中进行定制。

/*

参数概念解释：

master_binlog_dir=/data/mysql/data #设置master 保存binlog的位置，以便MHA可以找到master的日志

master_ip_failover_script=/usr/bin/master_ip_failover #设置自动failover时候的切换脚本

master_ip_online_change_script=/usr/bin/master_ip_online_change #设置手动切换时候的切换脚本

report_script=/usr/bin/send_report //设置发生切换后发送的报警的脚本

ping_interval=2 #设置监控主库，发送ping包的时间间隔，默认是3秒，尝试三次没有回应的时候自动进行failover

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的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

*/

6.3 master_ip_failover脚本代码

要想把keepalived服务引入MHA，我们只需要修改切换是触发的脚本文件master_ip_failover即可，在该脚本中添加在master发生宕机时对keepalived的处理。

在管理节点编辑脚本/usr/bin/master_ip_failover，修改后如下：

#!/usr/bin/env perluse 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 = '10.192.203.108';my $ssh_start_vip ="/etc/init.d/keepalived start";my $ssh_stop_vip ="/etc/init.d/keepalived stop"; GetOptions(   'command=s'          =>\$command,   'ssh_user=s'         =>\$ssh_user,   'orig_master_host=s' => \$orig_master_host,   'orig_master_ip=s'   =>\$orig_master_ip,   'orig_master_port=i' => \$orig_master_port,   'new_master_host=s'  =>\$new_master_host,   'new_master_ip=s'    =>\$new_master_ip,   'new_master_port=i'  =>\$new_master_port,); exit &main(); sub main {    print "\n\nIN SCRIPTTEST====$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 VIPon the old_mastersub 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";}

注意：my $vip = '10.192.203.108';这一行中的vip请根据情况改成自己的虚拟IP。

chmod +x /usr/bin/master_ip_failover

6.4 master_ip_online_change脚本代码

在管理节点编辑脚本/usr/bin/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#  itunder 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.,#  51Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA ## Note: This is a sample script and is notcomplete. 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 gettimeofdaytv_interval );use Data::Dumper; my $_tstart;my $_running_interval = 0.1;my ( $command,             $orig_master_is_new_slave, $orig_master_host, $orig_master_ip,      $orig_master_port,        $orig_master_user, $orig_master_password, $orig_master_ssh_user,     $new_master_host, $new_master_ip,       $new_master_port,         $new_master_user, $new_master_password, $new_master_ssh_user);my $vip = '10.192.203.108/32';my $key = '1';my $ssh_start_vip = "/etc/init.d/keepalivedstart";my $ssh_stop_vip = "/etc/init.d/keepalivedstop";my $orig_master_ssh_port = 22;my $new_master_ssh_port = 22;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, 'orig_master_ssh_user=s'   =>\$orig_master_ssh_user, '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, 'new_master_ssh_user=s'    =>\$new_master_ssh_user, 'orig_master_ssh_port=i'    =>\$orig_master_ssh_port, 'new_master_ssh_port=i'    =>\$new_master_ssh_port,); 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. DROP USER so that no app user can establish new connections    #3. Set read_only= 1 on the current master    #4. Kill current queries    #* 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. Disablingper-session binlog beforehand     $orig_master_handler->disable_log_bin_local();      print current_time_us() . " Drpping appuser on the orig master..\n";     #FIXME_xxx_drop_app_user($orig_master_handler);      ## 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 aredisconnected.. (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(exceptSUPER) 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 cancomplete     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 aredisconnected.. (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 applicationthreads..\n";     $orig_master_handler->kill_threads(@threads) if ( $#threads >= 0);     print current_time_us() . " done.\n";     $orig_master_handler->enable_log_bin_local();     $orig_master_handler->disconnect();      ## After finishing the script, MHA executes FLUSH TABLES WITH READ LOCK     eval {     `ssh -p$orig_master_ssh_port $orig_master_ssh_user\@$orig_master_host\" $ssh_stop_vip \"`;       };       if ($@) {           warn $@;       }     $exit_code = 0;   };   if ($@) {     warn "Got Error: $@\n";     exit $exit_code;    }   exit $exit_code;  } elsif ( $command eq "start" ) {   ## Activating master ip on the new master    #1. Create app user with write privileges    #2. Moving backup script if needed    #3. Register new master's ip to the catalog database # We don't return error even thoughactivating updatable accounts/ip failed so that we don't interrupt slaves'recovery.# If exit code is 0 or 10, MHA does notabort   my $exit_code = 10;   eval {     my $new_master_handler = new MHA::DBHelper();      # args: hostname, port, user, password, raise_error_or_not     $new_master_handler->connect( $new_master_ip, $new_master_port,       $new_master_user, $new_master_password, 1 );      ## Set read_only=0 on the new master     $new_master_handler->disable_log_bin_local();      print current_time_us() . " Setread_only=0 on the new master.\n";     $new_master_handler->disable_read_only();      ## Creating an app user on the new master     print current_time_us() . " Creating app user on the newmaster..\n";     #FIXME_xxx_create_app_user($new_master_handler);     $new_master_handler->enable_log_bin_local();     $new_master_handler->disconnect();      ## Update master ip on the catalog database, etc     `ssh -p$new_master_ssh_port $new_master_ssh_user\@$new_master_host\" $ssh_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;  }} 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;}

注意：需要把my $vip = '10.192.203.108/32';改成自己的vip即可。

chmod +x /usr/bin/master_ip_online_change

6.5 send_report脚本代码

在管理节点编辑脚本/usr/bin/send_report

#!/usr/bin/perl # Copyright (C) 2011 DeNA Co.,Ltd.## This program is free software; you can redistribute it and/or modify#  itunder 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.,#  51Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA ## Note: This is a sample script and is notcomplete. Modify the script based on your environment. use strict;use warnings FATAL => 'all';use Mail::Sender;use Getopt::Long; #new_master_host and new_slave_hosts areset only when recovering master succeededmy ( $dead_master_host, $new_master_host, $new_slave_hosts,$subject, $body );my $smtp='smtp.163.com';my $mail_from='xxxxxxx@163.com';my $mail_user='xxxxxxx@163.com';my $mail_pass='Password';my$mail_to=['949538827@qq.com','15521xxxx@139.com'];GetOptions( 'orig_master_host=s' => \$dead_master_host, 'new_master_host=s'  =>\$new_master_host, 'new_slave_hosts=s'  =>\$new_slave_hosts, 'subject=s'          =>\$subject, 'body=s'             => \$body,); mailToContacts($smtp,$mail_from,$mail_user,$mail_pass,$mail_to,$subject,$body); sub mailToContacts {   my ( $smtp, $mail_from, $user, $passwd, $mail_to, $subject, $msg ) = @_;   open my $DEBUG, "> /tmp/monitormail.log"       or die "Can't open the debug     file:$!\n";   my $sender = new Mail::Sender {       ctype       => 'text/plain;charset=utf-8',       encoding    => 'utf-8',       smtp        => $smtp,       from        => $mail_from,       auth        => 'LOGIN',       TLS_allowed => '0',       authid      => $user,       authpwd     => $passwd,       to          => $mail_to,       subject     => $subject,       debug       => $DEBUG   };    $sender->MailMsg(       {   msg   => $msg,           debug => $DEBUG       }    )or print $Mail::Sender::Error;   return 1;}   # Do whatever you want here exit 0; 注意：需要修改下以下几行内容：my $smtp='smtp.163.com';my $mail_from='xxxxxxx@163.com';my $mail_user='xxxxxxx@163.com';my $mail_pass='Password';my$mail_to=['949538827@qq.com','15521xxxx@139.com'];

#f赋予执行权限

chmod +x /usr/bin/send_report

注意：需要确保管理节点服务器可以正常发送邮件。可以先用sendEmail命令试下。

6.6 设置relay log的清除方式（在每个slave节点上）

从服务器配置文件要确保relay_log_purge=0，否则在masterha_check_repl时会报错warning,relay_log_purge=0 is not set on slave

主库将来发生切换变成一个从库后，记得在原先的主库上也执行该操作。

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。

（在mysql数据库中，删除大表时，通常也采用建立硬链接的方式）

7 检查mha manage是不是配置成功

7.1 检查ssh登录

 [root@pc2.ssh]#  masterha_check_ssh--conf=/etc/mha/app1.cnfMon Feb 13 15:35:25 2017 - [warning] Globalconfiguration file /etc/masterha_default.cnf not found. Skipping.Mon Feb 13 15:35:25 2017 - [info] Readingapplication default configuration from /etc/mha/app1.cnf..Mon Feb 13 15:35:25 2017 - [info] Readingserver configuration from /etc/mha/app1.cnf..Mon Feb 13 15:35:25 2017 - [info] StartingSSH connection tests..Mon Feb 13 15:35:26 2017 - [debug]Mon Feb 13 15:35:25 2017 - [debug]  Connecting via SSH fromroot@10.192.203.201(10.192.203.201:22) toroot@10.192.203.101(10.192.203.101:22)..Mon Feb 13 15:35:25 2017 - [debug]   ok.Mon Feb 13 15:35:25 2017 - [debug]  Connecting via SSH fromroot@10.192.203.201(10.192.203.201:22) toroot@10.192.203.102(10.192.203.102:22)..Mon Feb 13 15:35:26 2017 - [debug]   ok.Mon Feb 13 15:35:26 2017 - [debug]Mon Feb 13 15:35:25 2017 - [debug]  Connecting via SSH fromroot@10.192.203.101(10.192.203.101:22) toroot@10.192.203.201(10.192.203.201:22)..Mon Feb 13 15:35:25 2017 - [debug]   ok.Mon Feb 13 15:35:25 2017 - [debug]  Connecting via SSH fromroot@10.192.203.101(10.192.203.101:22) toroot@10.192.203.102(10.192.203.102:22)..Mon Feb 13 15:35:26 2017 - [debug]   ok.Mon Feb 13 15:35:27 2017 - [debug]Mon Feb 13 15:35:26 2017 - [debug]  Connecting via SSH fromroot@10.192.203.102(10.192.203.102:22) toroot@10.192.203.201(10.192.203.201:22)..Mon Feb 13 15:35:26 2017 - [debug]   ok.Mon Feb 13 15:35:26 2017 - [debug]  Connecting via SSH fromroot@10.192.203.102(10.192.203.102:22) toroot@10.192.203.101(10.192.203.101:22)..Mon Feb 13 15:35:27 2017 - [debug]   ok.Mon Feb 13 15:35:27 2017 - [info] All SSHconnection tests passed successfully.

假如ssh可以免密码登录其他几台服务器，但检查ssh时却报错：

 [root@PC .ssh]#  masterha_check_ssh--conf=/etc/mha/app1.cnf Fri Feb 10 10:04:35 2017 - [warning] Globalconfiguration file /etc/masterha_default.cnf not found. Skipping.Fri Feb 10 10:04:35 2017 - [info] Readingapplication default configuration from /etc/mha/app1.cnf..Fri Feb 10 10:04:35 2017 - [info] Readingserver configuration from /etc/mha/app1.cnf..Fri Feb 10 10:04:35 2017 - [info] StartingSSH connection tests..Fri Feb 10 10:04:36 2017 -[error][/usr/share/perl5/vendor_perl/MHA/SSHCheck.pm, ln63]Fri Feb 10 10:04:35 2017 - [debug]  Connecting via SSH fromroot@10.192.203.201(10.192.203.201:22) toroot@10.192.203.101(10.192.203.101:22)..Warning: Permanently added '10.192.203.201'(RSA) to the list of known hosts.Permission denied(publickey,gssapi-keyex,gssapi-with-mic,password).Fri Feb 10 10:04:35 2017 -[error][/usr/share/perl5/vendor_perl/MHA/SSHCheck.pm, ln111] SSH connectionfrom root@10.192.203.201(10.192.203.201:22) toroot@10.192.203.101(10.192.203.101:22) failed!Fri Feb 10 10:04:37 2017 - [debug]Fri Feb 10 10:04:36 2017 - [debug]  Connecting via SSH fromroot@10.192.203.101(10.192.203.101:22) toroot@10.192.203.201(10.192.203.201:22)..Fri Feb 10 10:04:36 2017 - [debug]   ok.Fri Feb 10 10:04:36 2017 - [debug]  Connecting via SSH fromroot@10.192.203.101(10.192.203.101:22) toroot@10.192.203.102(10.192.203.102:22)..Fri Feb 10 10:04:37 2017 - [debug]   ok.Fri Feb 10 10:04:38 2017 - [debug]Fri Feb 10 10:04:36 2017 - [debug]  Connecting via SSH fromroot@10.192.203.102(10.192.203.102:22) toroot@10.192.203.201(10.192.203.201:22)..Fri Feb 10 10:04:37 2017 - [debug]   ok.Fri Feb 10 10:04:37 2017 - [debug]  Connecting via SSH fromroot@10.192.203.102(10.192.203.102:22) to root@10.192.203.101(10.192.203.101:22)..Fri Feb 10 10:04:38 2017 - [debug]   ok.SSH Configuration Check Failed! at/usr/bin/masterha_check_ssh line 44

需要检查下：

① /etc/hosts文件是否配置正确；

② 密码文件是否ssh-copy-id到了自身服务器。

假如遇到这个错误，修正后，将.ssh下的内容全部清空，然后重新认证即可。

7.2 检查mysql replication是否配置成功

[root@pc2 app1]# masterha_check_repl--conf=/etc/mha/app1.cnf

Fri Feb 10 11:25:05 2017 - [warning] Globalconfiguration file /etc/masterha_default.cnf not found. Skipping.Fri Feb 10 11:25:05 2017 - [info] Readingapplication default configuration from /etc/mha/app1.cnf..Fri Feb 10 11:25:05 2017 - [info] Readingserver configuration from /etc/mha/app1.cnf..Fri Feb 10 11:25:05 2017 - [info]MHA::MasterMonitor version 0.56.Fri Feb 10 11:25:06 2017 -[error][/usr/share/perl5/vendor_perl/MHA/ServerManager.pm, ln193] There is noalive slave. We can't do failoverFri Feb 10 11:25:06 2017 -[error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln424] Errorhappened on checking configurations.  at/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm line 326Fri Feb 10 11:25:06 2017 -[error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln523] Errorhappened on monitoring servers.Fri Feb 10 11:25:06 2017 - [info] Got exitcode 1 (Not master dead). MySQL Replication Health is NOT OK!

明明我检查了复制状态都是正常的，为什么通不过呢？

解决办法：

需要确保master和备选master设置为双主复制。即让master也指向备选master。

再次验证，假如报错：

[root@pc2 mysql]# masterha_check_repl --conf=/etc/mha/app1.cnf

Mon Feb 13 17:21:52 2017 - [info]   Connecting toroot@10.192.203.101(10.192.203.101:22).. Checking slave recovery environment settings..   Opening /data/mysql/relay-log.info ... ok.   Relay log found at /data/mysql, up to slave1-relay-bin.000011   Temporary relay log file is /data/mysql/slave1-relay-bin.000011   Testing mysql connection and privileges..ERROR 1045 (28000): Accessdenied for user 'mha'@'slave1' (using password: YES)mysql command failed with rc 1:0! at/usr/bin/apply_diff_relay_logs line 375         main::check()called at /usr/bin/apply_diff_relay_logs line 497         eval{...} called at /usr/bin/apply_diff_relay_logs line 475         main::main()called at /usr/bin/apply_diff_relay_logs line 120Mon Feb 13 17:21:53 2017 -[error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln205] Slavessettings check failed!Mon Feb 13 17:21:53 2017 - [error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm,ln413] Slave configuration failed.Mon Feb 13 17:21:53 2017 -[error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln424] Errorhappened on checking configurations.  at/usr/bin/masterha_check_repl line 48Mon Feb 13 17:21:53 2017 -[error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln523] Errorhappened on monitoring servers.Mon Feb 13 17:21:53 2017 - [info] Got exitcode 1 (Not master dead). MySQL Replication Health is NOT OK!

解决办法：

在slave1上创建用户：

mysql> grant ALL PRIVILEGES ON *.* TO 'mha'@'slave1'identified by 'test';

Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

同理，在PC上创建用户：

mysql> grant ALL PRIVILEGES ON *.* TO 'mha'@'PC' identifiedby 'test';

Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

再次验证时，假如报错：

Can't exec "mysqlbinlog": No suchfile or directory at /usr/share/perl5/vendor_perl/MHA/BinlogManager.pm line106.

mysqlbinlog version command failed with rc1:0, please verify PATH, LD_LIBRARY_PATH, and client options

解决办法：

在所有数据节点上都创建一下软连接：

ln -s /usr/local/mysql/bin/mysqlbinlog /usr/bin/mysqlbinlog

再次验证，报错：

Testing mysql connection andprivileges..sh: mysql: command not found

mysql command failed with rc 127:0!

解决办法：

在所有数据节点上建立软连接：

ln -s /usr/local/mysql/bin/mysql /usr/bin/mysql

最后，一切正常：

[root@pc2 mysql]# masterha_check_repl --conf=/etc/mha/app1.cnf

Mon Feb 13 17:32:49 2017 - [warning] Globalconfiguration file /etc/masterha_default.cnf not found. Skipping.Mon Feb 13 17:32:49 2017 - [info] Readingapplication default configuration from /etc/mha/app1.cnf..Mon Feb 13 17:32:49 2017 - [info] Readingserver configuration from /etc/mha/app1.cnf..Mon Feb 13 17:32:49 2017 - [info]MHA::MasterMonitor version 0.56.Mon Feb 13 17:32:49 2017 - [info]Multi-master configuration is detected. Current primary(writable) master is10.192.203.201(10.192.203.201:3306)Mon Feb 13 17:32:49 2017 - [info] Masterconfigurations are as below:Master 10.192.203.101(10.192.203.101:3306),replicating from 10.192.203.201(10.192.203.201:3306), read-onlyMaster 10.192.203.201(10.192.203.201:3306),replicating from 10.192.203.101(10.192.203.101:3306) Mon Feb 13 17:32:49 2017 - [info] GTID failovermode = 0Mon Feb 13 17:32:49 2017 - [info] DeadServers:Mon Feb 13 17:32:49 2017 - [info] AliveServers:Mon Feb 13 17:32:49 2017 - [info]   10.192.203.201(10.192.203.201:3306)Mon Feb 13 17:32:49 2017 - [info]   10.192.203.101(10.192.203.101:3306)Mon Feb 13 17:32:49 2017 - [info]   10.192.203.102(10.192.203.102:3306)Mon Feb 13 17:32:49 2017 - [info] AliveSlaves:Mon Feb 13 17:32:49 2017 - [info]   10.192.203.101(10.192.203.101:3306)  Version=5.5.19-log (oldest major versionbetween slaves) log-bin:enabledMon Feb 13 17:32:49 2017 - [info]     Replicating from10.192.203.201(10.192.203.201:3306)Mon Feb 13 17:32:49 2017 - [info]     Primary candidate for the new Master(candidate_master is set)Mon Feb 13 17:32:49 2017 - [info]   10.192.203.102(10.192.203.102:3306)  Version=5.5.19-log (oldest major versionbetween slaves) log-bin:enabledMon Feb 13 17:32:49 2017 - [info]     Replicating from10.192.203.201(10.192.203.201:3306)Mon Feb 13 17:32:49 2017 - [info] CurrentAlive Master: 10.192.203.201(10.192.203.201:3306)Mon Feb 13 17:32:49 2017 - [info] Checkingslave configurations..Mon Feb 13 17:32:49 2017 - [info] Checkingreplication filtering settings..Mon Feb 13 17:32:49 2017 - [info]  binlog_do_db= , binlog_ignore_db=Mon Feb 13 17:32:49 2017 - [info]  Replication filtering check ok.Mon Feb 13 17:32:49 2017 - [info] GTID(with auto-pos) is not supportedMon Feb 13 17:32:49 2017 - [info] StartingSSH connection tests..Mon Feb 13 17:32:51 2017 - [info] All SSHconnection tests passed successfully.Mon Feb 13 17:32:51 2017 - [info] CheckingMHA Node version..Mon Feb 13 17:32:52 2017 - [info]  Version check ok.Mon Feb 13 17:32:52 2017 - [info] CheckingSSH publickey authentication settings on the current master..Mon Feb 13 17:32:52 2017 - [info]HealthCheck: SSH to 10.192.203.201 is reachable.Mon Feb 13 17:32:52 2017 - [info] MasterMHA Node version is 0.56.Mon Feb 13 17:32:52 2017 - [info] Checkingrecovery script configurations on 10.192.203.201(10.192.203.201:3306)..Mon Feb 13 17:32:52 2017 - [info]   Executing command: save_binary_logs--command=test --start_pos=4 --binlog_dir=/data/mysql--output_file=/var/tmp/save_binary_logs_test --manager_version=0.56--start_file=single-mysql-bin.000018Mon Feb 13 17:32:52 2017 - [info]   Connecting toroot@10.192.203.201(10.192.203.201:22).. Creating /var/tmp if not exists..   ok. Checking output directory is accessible or not..  ok. Binlog found at /data/mysql, up to single-mysql-bin.000018Mon Feb 13 17:32:52 2017 - [info] Binlogsetting check done.Mon Feb 13 17:32:52 2017 - [info] CheckingSSH publickey authentication and checking recovery script configurations on allalive slave servers..Mon Feb 13 17:32:52 2017 - [info]   Executing command : apply_diff_relay_logs--command=test --slave_user='mha' --slave_host=10.192.203.101--slave_ip=10.192.203.101 --slave_port=3306 --workdir=/var/tmp--target_version=5.5.19-log --manager_version=0.56--relay_log_info=/data/mysql/relay-log.info --relay_dir=/data/mysql/ --slave_pass=xxxMon Feb 13 17:32:52 2017 - [info]   Connecting toroot@10.192.203.101(10.192.203.101:22).. Checking slave recovery environment settings..   Opening /data/mysql/relay-log.info ... ok.   Relay log found at /data/mysql, up to slave1-relay-bin.000011    Temporaryrelay log file is /data/mysql/slave1-relay-bin.000011   Testing mysql connection and privileges.. done.   Testing mysqlbinlog output.. done.   Cleaning up test file(s).. done.Mon Feb 13 17:32:52 2017 - [info]   Executing command : apply_diff_relay_logs--command=test --slave_user='mha' --slave_host=10.192.203.102--slave_ip=10.192.203.102 --slave_port=3306 --workdir=/var/tmp--target_version=5.5.19-log --manager_version=0.56--relay_log_info=/data/mysql/relay-log.info --relay_dir=/data/mysql/ --slave_pass=xxxMon Feb 13 17:32:52 2017 - [info]   Connecting toroot@10.192.203.102(10.192.203.102:22).. Checking slave recovery environment settings..   Opening /data/mysql/relay-log.info ... ok.   Relay log found at /data/mysql, up to PC-relay-bin.000011   Temporary relay log file is /data/mysql/PC-relay-bin.000011   Testing mysql connection and privileges.. done.   Testing mysqlbinlog output.. done.   Cleaning up test file(s).. done.Mon Feb 13 17:32:53 2017 - [info] Slavessettings check done.Mon Feb 13 17:32:53 2017 - [info]10.192.203.201(10.192.203.201:3306)(current master) +--10.192.203.101(10.192.203.101:3306) +--10.192.203.102(10.192.203.102:3306) Mon Feb 13 17:32:53 2017 - [info] Checkingreplication health on 10.192.203.101..Mon Feb 13 17:32:53 2017 - [info]  ok.Mon Feb 13 17:32:53 2017 - [info] Checkingreplication health on 10.192.203.102..Mon Feb 13 17:32:53 2017 - [info]  ok.Mon Feb 13 17:32:53 2017 - [info] Checkingmaster_ip_failover_script status:Mon Feb 13 17:32:53 2017 - [info]   /usr/bin/master_ip_failover --command=status--ssh_user=root --orig_master_host=10.192.203.201--orig_master_ip=10.192.203.201 --orig_master_port=3306  IN SCRIPT TEST====/etc/init.d/keepalivedstop==/etc/init.d/keepalived start=== Checking the Status of the script.. OKMon Feb 13 17:32:53 2017 - [info]  OK.Mon Feb 13 17:32:53 2017 - [warning]shutdown_script is not defined.Mon Feb 13 17:32:53 2017 - [info] Got exitcode 0 (Not master dead). MySQL Replication Health is OK.

8 在管理端启动监控

nohup masterha_manager --conf=/etc/mha/app1.cnf --remove_dead_master_conf --ignore_last_failover < /dev/null > /var/log/mha/app1/manager.log 2>&1 &

#查看状态

masterha_check_status --conf=/etc/mha/app1.cnf

app1 (pid:3349) is running(0:PING_OK),master:10.192.203.201

9 验证故障转移

在10.192.203.201上关闭Mysql实例：

[root@pc2mha]# service mysqld stop

Shutting downMySQL... SUCCESS!

在管理节点上查看日志：

tail -f /var/log/mha/app1/manager.log

会看到：

Started automated(non-interactive)failover.Invalidated master IP address on10.192.203.201(10.192.203.201:3306)The latest slave10.192.203.101(10.192.203.101:3306) has all relay logs for recovery.Selected10.192.203.101(10.192.203.101:3306) as a new master.10.192.203.101(10.192.203.101:3306): OK:Applying all logs succeeded.10.192.203.101(10.192.203.101:3306): OK:Activated master IP address.10.192.203.102(10.192.203.102:3306): Thishost has the latest relay log events.Generating relay diff files from the latestslave succeeded.10.192.203.102(10.192.203.102:3306): OK:Applying all logs succeeded. Slave started, replicating from10.192.203.101(10.192.203.101:3306)10.192.203.101(10.192.203.101:3306):Resetting slave info succeeded.Master failover to10.192.203.101(10.192.203.101:3306) completed successfully.Mon Feb 13 17:44:28 2017 - [info] Sendingmail..Unknown option: conf

也收到了报警邮件：

Vip也漂移过来了：

[root@slave1 mysql]# ip addr1: lo: <LOOPBACK,UP,LOWER_UP> mtu16436 qdisc noqueue state UNKNOWN    link/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00   inet 127.0.0.1/8 scope host lo   inet6 ::1/128 scope host      valid_lft forever preferred_lft forever2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000   link/ether 08:00:27:04:05:16 brd ff:ff:ff:ff:ff:ff   inet 10.192.203.101/24 brd 10.192.203.255 scope global eth0   inet 10.192.203.108/32 scope global eth0   inet6 fe80::a00:27ff:fe04:516/64 scope link tentative dadfailed      valid_lft forever preferred_lft forever3: eth1:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000   link/ether 08:00:27:3a:ec:3c brd ff:ff:ff:ff:ff:ff   inet 10.0.10.5/24 brd 10.0.10.255 scope global eth1   inet6 fe80::a00:27ff:fe3a:ec3c/64 scope link tentative dadfailed      valid_lft forever preferred_lft forever

在PC上查看下slave状态：

mysql> show slave status \G;

*************************** 1. row***************************

Slave_IO_State: Waiting formaster to send event

Master_Host: 10.192.203.101

Master_User: rep_user

Master_Port: 3306

可以看到10.192.203.102复制自动指向了10.192.203.101了。

在现在的master上查看变量read_only,发现被自动关闭了，说明之前的slave现在可写了：

切换完成后，manager进程会自动挂掉：

[root@pc2 mysql]# masterha_check_status --conf=/etc/mha/app1.cnf

app1 is stopped(2:NOT_RUNNING).

mha配置文件被自己修改了(原主库的配置信息被删除掉了)：

[root@pc2 mha]# cat app1.cnf

[server default]manager_log=/var/log/mha/app1/manager.logmanager_workdir=/var/log/mha/app1.logmaster_binlog_dir=/data/mysqlmaster_ip_failover_script=/usr/bin/master_ip_failovermaster_ip_online_change_script=/usr/bin/master_ip_online_changepassword=testping_interval=2repl_password=beijingrepl_user=rep_userreport_script=/usr/bin/send_reportssh_user=rootuser=mha [server2]candidate_master=1check_repl_delay=0hostname=10.192.203.101port=3306 [server3]hostname=10.192.203.102port=3306

现在的主库10.192.203.101上已经没有它原先的主从复制信息：

mysql> showslave status \G;

Empty set (0.00sec)

ERROR:

No queryspecified

接下来我们该做的事情：

① 找出主库挂到的原因，并修复之

② 确保原先的主库现在已追赶上现在的主库，并继续正确复制

③ 在现在的主库上change master to指向原来的主库开始复制，为将来故障切换做好准备。

④ 检查当前主从复制状态是否正常(masterha_check_repl--conf=/etc/mha/app1.cnf)

⑤ 启动原先主库keepalive进程

⑥ 确保原先主库配置文件(read_only设置为1，relay_log_purge=0)

⑦ 修改mha配置文件，将原先的主库信息重新加入

⑧ 启动manager进程,检查mha状态是否正常

10 在线切换

在许多情况下，需要将现有的主服务器迁移到另外一台服务器上。比如主服务器硬件故障，RAID 控制卡需要重建，将主服务器移到性能更好的服务器上等等。维护主服务器引起性能下降，导致停机时间至少无法写入数据。另外，阻塞或杀掉当前运行的会话会导致主主之间数据不一致的问题发生。 MHA 提供快速切换和优雅的阻

塞写入，这个切换过程只需要 0.5-2s 的时间，这段时间内数据是无法写入的。在很多情况下，0.5-2s 的阻塞写入是可以接受的。因此切换主服务器不需要计划分配维护时间窗口。

MHA在线切换的大概过程：

（1）检测复制设置和确定当前主服务器

（2）确定新的主服务器

（3）阻塞写入到当前主服务器

（4）等待所有从服务器赶上复制

（5）授予写入到新的主服务器

（6）重新设置从服务器

假如现在我想从10.192.203.101切换回10.192.203.201，通过在线切换的方式完成。

10.1 停掉MHA监控

masterha_stop --conf=/etc/mha/app1.cnf

10.2 在线切换

[root@pc2 bin]# masterha_master_switch--conf=/etc/mha/app1.cnf --master_state=alive --new_master_host=10.192.203.201--new_master_port=3306 --orig_master_is_new_slave --running_updates_limit=10000

Tue Feb 14 02:44:20 2017 - [info]MHA::MasterRotate version 0.56.Tue Feb 14 02:44:20 2017 - [info] Startingonline master switch..Tue Feb 14 02:44:20 2017 - [info]Tue Feb 14 02:44:20 2017 - [info] * Phase1: Configuration Check Phase..Tue Feb 14 02:44:20 2017 - [info]Tue Feb 14 02:44:20 2017 - [warning] Globalconfiguration file /etc/masterha_default.cnf not found. Skipping.Tue Feb 14 02:44:20 2017 - [info] Readingapplication default configuration from /etc/mha/app1.cnf..Tue Feb 14 02:44:20 2017 - [info] Readingserver configuration from /etc/mha/app1.cnf..Tue Feb 14 02:44:20 2017 - [info]Multi-master configuration is detected. Current primary(writable) master is10.192.203.101(10.192.203.101:3306)Tue Feb 14 02:44:20 2017 - [info] Masterconfigurations are as below:Master 10.192.203.101(10.192.203.101:3306),replicating from 10.192.203.201(10.192.203.201:3306)Master 10.192.203.201(10.192.203.201:3306),replicating from 10.192.203.101(10.192.203.101:3306), read-only Tue Feb 14 02:44:20 2017 - [info] GTIDfailover mode = 0Tue Feb 14 02:44:20 2017 - [info] CurrentAlive Master: 10.192.203.101(10.192.203.101:3306)Tue Feb 14 02:44:20 2017 - [info] AliveSlaves:Tue Feb 14 02:44:20 2017 - [info]   10.192.203.201(10.192.203.201:3306)  Version=5.5.19-log (oldest major versionbetween slaves) log-bin:enabledTue Feb 14 02:44:20 2017 - [info]     Replicating from10.192.203.101(10.192.203.101:3306)Tue Feb 14 02:44:20 2017 - [info]   10.192.203.102(10.192.203.102:3306)  Version=5.5.19-log (oldest major versionbetween slaves) log-bin:enabledTue Feb 14 02:44:20 2017 - [info]     Replicating from10.192.203.101(10.192.203.101:3306) It is better to execute FLUSHNO_WRITE_TO_BINLOG TABLES on the master before switching. Is it ok to executeon 10.192.203.101(10.192.203.101:3306)? (YES/no): yesTue Feb 14 02:45:03 2017 - [info] ExecutingFLUSH NO_WRITE_TO_BINLOG TABLES. This may take long time..Tue Feb 14 02:45:03 2017 - [info]  ok.Tue Feb 14 02:45:03 2017 - [info] CheckingMHA is not monitoring or doing failover..Tue Feb 14 02:45:03 2017 - [info] Checkingreplication health on 10.192.203.201..Tue Feb 14 02:45:03 2017 - [info]  ok.Tue Feb 14 02:45:03 2017 - [info] Checkingreplication health on 10.192.203.102..Tue Feb 14 02:45:03 2017 - [info]  ok.Tue Feb 14 02:45:03 2017 - [info]10.192.203.201 can be new master.Tue Feb 14 02:45:03 2017 - [info]From:10.192.203.101(10.192.203.101:3306)(current master) +--10.192.203.201(10.192.203.201:3306) +--10.192.203.102(10.192.203.102:3306) To:10.192.203.201(10.192.203.201:3306) (newmaster) +--10.192.203.102(10.192.203.102:3306) +--10.192.203.101(10.192.203.101:3306) Starting master switch from10.192.203.101(10.192.203.101:3306) to 10.192.203.201(10.192.203.201:3306)?(yes/NO): yesTue Feb 14 02:45:09 2017 - [info] Checkingwhether 10.192.203.201(10.192.203.201:3306) is ok for the new master..Tue Feb 14 02:45:09 2017 - [info]  ok.Tue Feb 14 02:45:09 2017 - [info] ** Phase1: Configuration Check Phase completed.Tue Feb 14 02:45:09 2017 - [info]Tue Feb 14 02:45:09 2017 - [info] * Phase2: Rejecting updates Phase..Tue Feb 14 02:45:09 2017 - [info]Tue Feb 14 02:45:09 2017 - [info] Executingmaster ip online change script to disable write on the current master:Tue Feb 14 02:45:09 2017 - [info]   /usr/bin/master_ip_online_change--command=stop --orig_master_host=10.192.203.101--orig_master_ip=10.192.203.101 --orig_master_port=3306--orig_master_user='mha' --orig_master_password='test'--new_master_host=10.192.203.201 --new_master_ip=10.192.203.201--new_master_port=3306 --new_master_user='mha' --new_master_password='test' --orig_master_ssh_user=root--new_master_ssh_user=root  --orig_master_is_new_slaveTue Feb 14 02:45:09 2017 728241 Setread_only on the new master.. ok.Tue Feb 14 02:45:09 2017 733969 Drpping appuser on the orig master..Tue Feb 14 02:45:09 2017 735861 Set read_only=1on the orig master.. ok.Tue Feb 14 02:45:09 2017 739394 Killing allapplication threads..Tue Feb 14 02:45:09 2017 739431 done.SIOCSIFFLAGS: Cannot assign requestedaddressTue Feb 14 02:45:09 2017 - [info]  ok.Tue Feb 14 02:45:09 2017 - [info] Lockingall tables on the orig master to reject updates from everybody (includingroot):Tue Feb 14 02:45:09 2017 - [info] ExecutingFLUSH TABLES WITH READ LOCK..Tue Feb 14 02:45:09 2017 - [info]  ok.Tue Feb 14 02:45:09 2017 - [info] Origmaster binlog:pos is single-mysql-bin.000009:997.Tue Feb 14 02:45:09 2017 - [info]  Waiting to execute all relay logs on10.192.203.201(10.192.203.201:3306)..Tue Feb 14 02:45:09 2017 - [info]  master_pos_wait(single-mysql-bin.000009:997)completed on 10.192.203.201(10.192.203.201:3306). Executed 0 events.Tue Feb 14 02:45:09 2017 - [info]   done.Tue Feb 14 02:45:09 2017 - [info] Gettingnew master's binlog name and position..Tue Feb 14 02:45:09 2017 - [info]  single-mysql-bin.000022:107Tue Feb 14 02:45:09 2017 - [info]  All other slaves should start replicationfrom here. Statement should be: CHANGE MASTER TO MASTER_HOST='10.192.203.201',MASTER_PORT=3306, MASTER_LOG_FILE='single-mysql-bin.000022', MASTER_LOG_POS=107,MASTER_USER='rep_user', MASTER_PASSWORD='xxx';Tue Feb 14 02:45:09 2017 - [info] Executingmaster ip online change script to allow write on the new master:Tue Feb 14 02:45:09 2017 - [info]   /usr/bin/master_ip_online_change--command=start --orig_master_host=10.192.203.101 --orig_master_ip=10.192.203.101--orig_master_port=3306 --orig_master_user='mha' --orig_master_password='test'--new_master_host=10.192.203.201 --new_master_ip=10.192.203.201--new_master_port=3306 --new_master_user='mha' --new_master_password='test'--orig_master_ssh_user=root --new_master_ssh_user=root   --orig_master_is_new_slaveTue Feb 14 02:45:09 2017 946501 Setread_only=0 on the new master.Tue Feb 14 02:45:09 2017 947009 Creatingapp user on the new master..Tue Feb 14 02:45:10 2017 - [info]  ok.Tue Feb 14 02:45:10 2017 - [info]Tue Feb 14 02:45:10 2017 - [info] *Switching slaves in parallel..Tue Feb 14 02:45:10 2017 - [info]Tue Feb 14 02:45:10 2017 - [info] -- Slaveswitch on host 10.192.203.102(10.192.203.102:3306) started, pid: 8353Tue Feb 14 02:45:10 2017 - [info]Tue Feb 14 02:45:10 2017 - [info] Logmessages from 10.192.203.102 ...Tue Feb 14 02:45:10 2017 - [info]Tue Feb 14 02:45:10 2017 - [info]  Waiting to execute all relay logs on10.192.203.102(10.192.203.102:3306)..Tue Feb 14 02:45:10 2017 - [info]  master_pos_wait(single-mysql-bin.000009:997)completed on 10.192.203.102(10.192.203.102:3306). Executed 0 events.Tue Feb 14 02:45:10 2017 - [info]   done.Tue Feb 14 02:45:10 2017 - [info]  Resetting slave10.192.203.102(10.192.203.102:3306) and starting replication from the newmaster 10.192.203.201(10.192.203.201:3306)..Tue Feb 14 02:45:10 2017 - [info]  Executed CHANGE MASTER.Tue Feb 14 02:45:10 2017 - [info]  Slave started.Tue Feb 14 02:45:10 2017 - [info] End oflog messages from 10.192.203.102 ...Tue Feb 14 02:45:10 2017 - [info]Tue Feb 14 02:45:10 2017 - [info] -- Slaveswitch on host 10.192.203.102(10.192.203.102:3306) succeeded.Tue Feb 14 02:45:10 2017 - [info] Unlockingall tables on the orig master:Tue Feb 14 02:45:10 2017 - [info] ExecutingUNLOCK TABLES..Tue Feb 14 02:45:10 2017 - [info]  ok.Tue Feb 14 02:45:10 2017 - [info] Startingorig master as a new slave..Tue Feb 14 02:45:10 2017 - [info]  Resetting slave10.192.203.101(10.192.203.101:3306) and starting replication from the newmaster 10.192.203.201(10.192.203.201:3306)..Tue Feb 14 02:45:10 2017 - [info]  Executed CHANGE MASTER.Tue Feb 14 02:45:10 2017 - [info]  Slave started.Tue Feb 14 02:45:10 2017 - [info] All newslave servers switched successfully.Tue Feb 14 02:45:10 2017 - [info]Tue Feb 14 02:45:10 2017 - [info] * Phase5: New master cleanup phase..Tue Feb 14 02:45:10 2017 - [info]Tue Feb 14 02:45:10 2017 - [info]  10.192.203.201: Resetting slave infosucceeded.Tue Feb 14 02:45:10 2017 - [info] Switchingmaster to 10.192.203.201(10.192.203.201:3306) completed successfully.

中间需要手动输入两个yes。

10.3 检查是否切换成功

执行masterha_check_repl --conf=/etc/mha/app1.cnf验证下当前主从配置是否正确。

登录各从库，验证下现在复制是否已指向新的主库。

现在10.192.203.101, 10.192.203.102复制都指向10.192.203.201.

10.192.203.201上没有复制信息：

mysql> show slave status \G;

Empty set (0.00 sec)

ERROR:

No query specified

发现在线切换后有如下特点：

① ：在线切换完成后，其他库复制都会指向现在的主库。现在的主库上原先的复制信息被清除

② ：mha配置文件里原先主库的信息没有被删除。

③ ：原先的主库自动变成只读，现在的主库自动变成可写。

④ ：原来主库上的vip自动漂移到了现在的主库上。

10.4 后续操作

①：在线切换完成后，现在的主库仍然需要change master to原先的主库,然后开始复制。

② ：启动原先主库的keepalive进程

③：启动mha监控

我发现当备用主库宕机后，假如主库也宕掉了，此时mha无法自动切换到其他slave上。错误日志：

Wed Feb 15 21:42:04 2017 -[error][/usr/share/perl5/vendor_perl/MHA/ServerManager.pm, ln492] Server 10.192.203.101(10.192.203.101:3306) isdead, but must be alive! Check server settings.

Wed Feb 15 21:42:04 2017 -[error][/usr/share/perl5/vendor_perl/MHA/ManagerUtil.pm, ln177] Got ERROR: at/usr/share/perl5/vendor_perl/MHA/MasterFailover.pm line 268

--本篇文章参考了：http://www.cnblogs.com/xuanzhi201111/p/4231412.html

--文章如有不当之处，欢迎指出！

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