介绍利用keepalived构建高可用MySQL-HA，保证两台MySQL数据的一致性，然后用keepalived实现虚拟IP，通过keepalived自带的服务监控功能来实现MySQL故障时自动切换。
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关于MySQL-HA，目前有多种解决方案，比如heartbeat、drbd、mmm、共享存储，但是它们各有优缺点。heartbeat、drbd配置较为复杂，需要自己写脚本才能实现MySQL自动切换，对于不会脚本语言的人来说，这无疑是一种脑裂问题；对于mmm，生产环境中很少有人用，且mmm 管理端需要单独运行一台服务器上，要是想实现高可用，就得对mmm管理端做HA，这样无疑又增加了硬件开支；对于共享存储，个人觉得MySQL数据还是放在本地较为安全，存储设备毕竟存在单点隐患。使用MySQL双master+keepalived是一种非常好的解决方案，在MySQL-HA环境中，MySQL互为主从关系，这样就保证了两台MySQL数据的一致性，然后用keepalived实现虚拟IP，通过keepalived自带的服务监控功能来实现MySQL故障时自动切换。
下面，我把即将上线的一个生产环境中的架构与大家分享一下，看一下这个架构中，MySQL-HA是如何实现的，环境拓扑如下
MySQL-VIP：192.168.1.90
MySQL-master1：192.168.1.91
MySQL-master2：192.168.1.92
OS版本：CentOS 5.4
MySQL版本：5.0.89
Keepalived版本：1.1.20
一、MySQL master-master配置
[root@localhost ~]# mysql -uroot
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.0.77 Source distribution
Type 'help;' or '\h' for help. Type '\c' toclear the buffer.
mysql> GRANT ALL PRIVILEGES ON *.* TOroot@'%';
Query OK, 0 rows affected (0.01 sec)
mysql> use mysql;
Reading table information for completion oftable and column names
You can turn off this feature to get aquicker startup with -A
Database changed
mysql> update user setPassword=password('bee') where user='root';
Query OK, 4 rows affected (0.01 sec)
Rows matched: 4 Changed: 4 Warnings: 0
mysql> show master status;
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB |Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| MySQL-bin.000001 | 328 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
1、修改MySQL配置文件
[mysqld]
log-bin=MySQL-bin
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
server-id = 2
replicate-same-server-id = 0
auto-increment-increment = 2
auto-increment-offset = 2
replicate-ignore-db=test
replicate-ignore-db=mysql
slave-skip-errors=all
# Default to using old password format forcompatibility with mysql 3.x
# clients (those using the mysqlclient10compatibility package).
old_passwords=1
# Disabling symbolic-links is recommended toprevent assorted security risks;
# to do so, uncomment this line:
# symbolic-links=0
[replication]
master-host=192.168.1.91
master-user=replication
master-password=replication
master-port=3306
master-connect-retry=60
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
两台MySQL均如要开启binlog日志功能，开启方法：在MySQL配置文件[MySQLd]段中加上log-bin=MySQL-bin选项
两台MySQL的server-ID不能一样，默认情况下两台MySQL的serverID都是1，需将其中一台修改为2即可
2、将192.168.1.201设为192.168.1.202的主服务器
在192.168.1.201上新建授权用户
MySQL> grant replication slave on *.* to 'replication'@'%' identified by 'replication';
Query OK, 0 rows affected (0.00 sec)
MySQL> show master status;
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| MySQL-bin.000003 | 374 | | |
+----