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：CentOS 5.9下安装配置keepalived
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1、当前主机环境及MHA配置
[root@vdbsrv1 ~]# more /etc/hosts 127.0.0.1 localhost.localdomain localhost 192.168.1.6 vdbsrv1 #master 192.168.1.7 vdbsrv2 #slave1 192.168.1.8 vdbsrv3 #slave2 192.168.1.12 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/app1 manager_log=/var/log/masterha/app1/manager.log user=mha password=xxx ssh_user=root repl_user=repl repl_password=repl ping_interval=1 shutdown_script="" master_ip_online_change_script="" report_script="" master_ip_failover_script=/tmp/master_ip_failover [server1] hostname=vdbsrv1 master_binlog_dir=/data/mysqldata [server2] hostname=vdbsrv2 master_binlog_dir=/data/mysqldata [server3] hostname=vdbsrv3 master_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 192.168.1.13 PING 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 192.168.1.13 PING 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.