MHA能够在10~30秒内实现自动故障检测和故障转移，适用于对高可用性，数据完整性要求较高的场合。要做到无缝切换，还需要依赖于VIP漂移。VIP漂移比较常用的方式为使用keepalived或者使用脚本直接实现。脚本方式无须安装及复杂配置，相对简单。本文描述了基于脚本实现VIP切换。

  对于keepalived的相关配置可以参考：

 

1、当前主机环境及MHA配置  

[root@vdbsrv1 ~]# more /etc/hosts127.0.0.1    localhost.localdomain localhost192.168.1.6  vdbsrv1  #master192.168.1.7  vdbsrv2  #slave1192.168.1.8  vdbsrv3  #slave2192.168.1.12 vdbsrv4  #manager

###os环境

[root@vdbsrv4 ~]# more /etc/issue CentOS release 5.9 (Final)Kernel \r on an \m

 

###mysql环境

[root@vdbsrv4 ~]# mysql -e "show variables like 'version'"+---------------+------------+| Variable_name | Value      |+---------------+------------+| version       | 5.6.22-log |+---------------+------------+

[root@vdbsrv4 ~]# masterha_manager --version

masterha_manager version 0.56.

 

###MHA配置信息

[root@vdbsrv4 ~]$ more /etc/masterha/app1.cnf [server default]manager_workdir=/var/log/masterha/app1manager_log=/var/log/masterha/app1/manager.log

user=mha

password=xxxssh_user=rootrepl_user=repl   repl_password=repl   ping_interval=1shutdown_script=""master_ip_online_change_script=""report_script=""master_ip_failover_script=/tmp/master_ip_failover  [server1]hostname=vdbsrv1master_binlog_dir=/data/mysqldata

[server2]

hostname=vdbsrv2master_binlog_dir=/data/mysqldata

[server3]

hostname=vdbsrv3master_binlog_dir=/data/mysqldata/ #candidate_master=1

 

2、测试VIP切换

###测试VIP(192.168.1.13)是否被启用

[root@vdbsrv4 ~]# ping 192.168.1.13PING 192.168.1.13 (192.168.1.13) 56(84) bytes of data.From 192.168.1.12 icmp_seq=10 Destination Host Unreachable

###为主机vdbsrv1添加VIP

[root@vdbsrv4 ~]# ssh vdbsrv1 "/sbin/ifconfig eth0:0 192.168.1.13 netmask 255.255.255.0 up"

###校验VIP是否成功启用

[root@vdbsrv4 ~]# ping 192.168.1.13PING 192.168.1.13 (192.168.1.13) 56(84) bytes of data.64 bytes from 192.168.1.13: icmp_seq=1 ttl=64 time=1.82 ms

 

###开启MHA

[root@vdbsrv4 ~]# masterha_manager --conf=/etc/masterha/app1.cnf &

 

###模拟主库宕机

[root@vdbsrv4 ~]# ssh vdbsrv1 "killall -r mysqld"

 

###查看管理节点日志，可以看到VIP已经漂移

[root@vdbsrv4 ~]# grep VIP /var/log/masterha/app1/manager.log Disabling the VIP on old master: vdbsrv1 Enabling the VIP - 192.168.1.13/24 on the new master - vdbsrv2

 

###验证VIP是否位于节点vdbsrv2

[root@vdbsrv4 ~]# ssh vdbsrv2 "ifconfig |grep 1.13 -B1"eth0:0    Link encap:Ethernet  HWaddr 00:0C:29:5F:B2:EB            inet addr:192.168.1.13  Bcast:192.168.1.255  Mask:255.255.255.0

 

######查看管理节点MHA切换日志

[root@vdbsrv4 ~]# tail /var/log/masterha/app1/manager.log Invalidated master IP address on vdbsrv1(192.168.1.6:3306)The latest slave vdbsrv2(192.168.1.7:3306) has all relay logs for recovery.Selected vdbsrv2(192.168.1.7:3306) as a new master.vdbsrv2(192.168.1.7:3306): OK: Applying all logs succeeded.vdbsrv2(192.168.1.7:3306): OK: Activated master IP address.vdbsrv3(192.168.1.8:3306): This host has the latest relay log events.Generating relay diff files from the latest slave succeeded.vdbsrv3(192.168.1.8:3306): OK: Applying all logs succeeded. Slave started, replicating from vdbsrv2(192.168.1.7:3306)vdbsrv2(192.168.1.7:3306): Resetting slave info succeeded.Master failover to vdbsrv2(192.168.1.7:3306) completed successfully.

 

3、VIP切换perl脚本

[root@vdbsrv4 app1]# more /tmp/master_ip_failover #!/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 = '192.168.1.13/24';my $key = '0';my $ssh_start_vip = "/sbin/ifconfig eth0:$key $vip";my $ssh_stop_vip = "/sbin/ifconfig eth0:$key down";GetOptions(    'command=s'          => \$command,    'ssh_user=s'         => \$ssh_user,    'orig_master_host=s' => \$orig_master_host,    'orig_master_ip=s'   => \$orig_master_ip,    'orig_master_port=i' => \$orig_master_port,    'new_master_host=s'  => \$new_master_host,    'new_master_ip=s'    => \$new_master_ip,    'new_master_port=i'  => \$new_master_port,);exit &main();sub main {    print "\n\nIN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===\n\n";    if ( $command eq "stop" || $command eq "stopssh" ) {        my $exit_code = 1;        eval {            print "Disabling the VIP on old master: $orig_master_host \n";            &stop_vip();            $exit_code = 0;        };        if ($@) {            warn "Got Error: $@\n";            exit $exit_code;        }        exit $exit_code;    }    elsif ( $command eq "start" ) {        my $exit_code = 10;        eval {            print "Enabling the VIP - $vip on the new master - $new_master_host \n";            &start_vip();            $exit_code = 0;        };        if ($@) {            warn $@;            exit $exit_code;        }        exit $exit_code;    }    elsif ( $command eq "status" ) {        print "Checking the Status of the script.. OK \n";        exit 0;    }    else {        &usage();        exit 1;    }}sub start_vip() {    `ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`;}sub stop_vip() {     return 0  unless  ($ssh_user);    `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";}