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。

AD:

 

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 ~]#  -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 | | |

+------------------+----------+--------------+------------------+

1 row in set (0.00 sec)

在192.168.1.202上将192.168.1.201设为自己的主服务器

MySQL> change master to master_host='192.168.1.201',master_user='replication',master_password='replication',master_log_file='MySQL-bin.000003',master_log_pos=374;

Query OK, 0 rows affected (0.05 sec)



MySQL> start slave;

Query OK, 0 rows affected (0.00 sec)



MySQL> show slave status\G

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

Slave_IO_State: Waiting for master to send event

Master_Host: 192.168.1.201

Master_User: replication

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: MySQL-bin.000003

Read_Master_Log_Pos: 374

Relay_Log_File: MySQL-master2-relay-bin.000002

Relay_Log_Pos: 235

Relay_Master_Log_File: MySQL-bin.000003

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

Replicate_Do_DB:

Replicate_Ignore_DB:

Replicate_Do_Table:

Replicate_Ignore_Table:

Replicate_Wild_Do_Table:

Replicate_Wild_Ignore_Table:

Last_Errno: 0

Last_Error:

Skip_Counter: 0

Exec_Master_Log_Pos: 374

Relay_Log_Space: 235

Until_Condition: None

Until_Log_File:

Until_Log_Pos: 0

Master_SSL_Allowed: No

Master_SSL_CA_File:

Master_SSL_CA_Path:

Master_SSL_Cert:

Master_SSL_Cipher:

Master_SSL_Key:

Seconds_Behind_Master: 0

1 row in set (0.00 sec)

3、将192.168.1.202设为192.168.1.201的主服务器

在192.168.1.202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 | | |

+------------------+----------+--------------+------------------+

1 row in set (0.00 sec)

在192.168.1.201上,将192.168.1.202设为自己的主服务器

MySQL> change master to master_host='192.168.1.202',master_user='replication',master_password='replication',master_log_file='MySQL-bin.000003',master_log_pos=374;

Query OK, 0 rows affected (0.05 sec)



MySQL> start slave;

Query OK, 0 rows affected (0.00 sec)



MySQL> show slave status\G

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

Slave_IO_State: Waiting for master to send event

Master_Host: 192.168.1.202

Master_User: replication

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: MySQL-bin.000003

Read_Master_Log_Pos: 374

Relay_Log_File: MySQL-master1-relay-bin.000002

Relay_Log_Pos: 235

Relay_Master_Log_File: MySQL-bin.000003

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

Replicate_Do_DB:

Replicate_Ignore_DB:

Replicate_Do_Table:

Replicate_Ignore_Table:

Replicate_Wild_Do_Table:

Replicate_Wild_Ignore_Table:

Last_Errno: 0

Last_Error:

Skip_Counter: 0

Exec_Master_Log_Pos: 374

Relay_Log_Space: 235

Until_Condition: None

Until_Log_File:

Until_Log_Pos: 0

Master_SSL_Allowed: No

Master_SSL_CA_File:

Master_SSL_CA_Path:

Master_SSL_Cert:

Master_SSL_Cipher:

Master_SSL_Key:

Seconds_Behind_Master: 0

1 row in set (0.00 sec)

4、MySQL同步测试

如上述均正确配置,现在任何一台MySQL上更新数据都会同步到另一台MySQL,MySQL同步在此不再演示

二、keepalived安装及配置

1、192.168.1.201服务器上keepalived安装及配置

安装keepalived

#tar zxvf keepalived-1.1.20.tar.gz

#cd keepalived-1.1.20

#./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.18-164.el5-i686

#make && make install

[root@master2 ~]#/usr/local/keepalived/sbin/keepalived -D

[root@master2 ~]# ps -aux|grep keepalived

Warning: bad syntax, perhaps a bogus '-'?See /usr/share/doc/procps-3.2.7/FAQ

root 4101 0.3 0.1 35828 632 ? Ss 15:41 0:00/usr/local/keepalived/sbin/keepalived -D

root 4102 0.7 0.4 39988 1620 ? S 15:41 0:00/usr/local/keepalived/sbin/keepalived -D

root 4103 0.5 0.3 39988 1092 ? S 15:41 0:00/usr/local/keepalived/sbin/keepalived -D

root 4106 0.0 0.2 61136 716 pts/0 R+ 15:41 0:00 grep keepalived

配置keepalived

ln -sv /usr/src/kernels/2.6.18-194.el5-x86_64//usr/src/linux

我们自己在新建一个配置文件,默认情况下keepalived启动时会去/etc/keepalived目录下找配置文件

#mkdir /etc/keepalived

#vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

notification_email {



}

notification_email_from 

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id MySQL-ha

}



vrrp_instance VI_1 {

state BACKUP #两台配置此处均是BACKUP

interface eth0

virtual_router_id 51

priority 100 #优先级,另一台改为90

advert_int 1

nopreempt #不抢占,只在优先级高的机器上设置即可,优先级低的机器不设置

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.1.200

}

}



virtual_server 192.168.1.200 3306 {

delay_loop 2 #每个2秒检查一次real_server状态

lb_algo wrr #LVS算法

lb_kind DR #LVS模式

persistence_timeout 60 #会话保持时间

protocol TCP

real_server 192.168.1.201 3306 {

weight 3

notify_down /usr/local/MySQL/bin/MySQL.sh #检测到服务down后执行的脚本

TCP_CHECK {

connect_timeout 10 #连接超时时间

nb_get_retry 3 #重连次数

delay_before_retry 3 #重连间隔时间

connect_port 3306 #健康检查端口

}

}

编写检测服务down后所要执行的脚本

#vi /usr/local/MySQL/bin/MySQL.sh

#!/bin/sh

pkill keepalived

#chmod +x /usr/local/MySQL/bin/MySQL.sh

注:此脚本是上面配置文件notify_down选项所用到的,keepalived使用notify_down选项来检查real_server的服务状态,当发现real_server服务故障时,便触发此脚本;我们可以看到,脚本就一个命令,通过pkillkeepalived强制杀死keepalived进程,从而实现了MySQL故障自动转移。另外,我们不用担心两个MySQL会同时提供数据更新操作,因为每台MySQL上的keepalived的配置里面只有本机MySQL的IP+VIP,而不是两台MySQL的IP+VIP

启动keepalived

#/usr/local/keepalived/sbin/keepalived –D

#ps -aux | grep keepalived

测试

找一台局域网PC,然后去ping MySQL的VIP,这时候MySQL的VIP是可以ping的通的

停止MySQL服务,看keepalived健康检查程序是否会触发我们编写的脚本

2、192.168.1.202上keepalived安装及配置

安装keepalived

#tar zxvf keepalived-1.1.20.tar.gz

#cd keepalived-1.1.20

#./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.18-164.el5-i686

#make && make install

配置keepalived

这台配置和上面基本一样,但有三个地方不同:优先级为90、无抢占设置、real_server为本机IP

#mkdir /etc/keepalived

#vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

notification_email {



}

notification_email_from 

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id MySQL-ha

}



vrrp_instance VI_1 {

state BACKUP

interface eth0

virtual_router_id 51

priority 90

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.1.200

}

}



virtual_server 192.168.1.200 3306 {

delay_loop 2

lb_algo wrr

lb_kind DR

persistence_timeout 60

protocol TCP

real_server 192.168.1.202 3306 {

weight 3

notify_down /usr/local/MySQL/bin/MySQL.sh

TCP_CHECK {

connect_timeout 10

nb_get_retry 3

delay_before_retry 3

connect_port 3306

}

}

编写检测服务down后所要执行的脚本

#vi /usr/local/MySQL/bin/MySQL.sh

#!/bin/sh

pkill keepalived

#chmod +x /usr/local/MySQL/bin/MySQL.sh



启动keepalived

#/usr/local/keepalived/sbin/keepalived –D

#ps -aux | grep keepalived

测试

停止MySQL服务,看keepalived健康检查程序是否会触发我们编写的脚本

三、测试

MySQL远程登录测试

我们找一台安装有MySQL客户端的,然后登录VIP,看是否能登录,在登录之两台MySQL服务器都要授权允许从远程登录

MySQL> grant all privileges on *.* to 'root'@'%' identified by '123456';

Query OK, 0 rows affected (0.00 sec)



MySQL> flush privileges;

Query OK, 0 rows affected (0.00 sec)

使用客户端登录VIP测试

C:\MySQL\bin>MySQL.exe -uroot -p123456 -h192.168.1.200 -P3306

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 224

Server version: 5.0.89-log Source distribution



Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.



MySQL>

● keepalived故障转移测试

※在windows客户端一直去ping VIP,然后关闭192.168.1.201上的keepalived,正常情况下VIP就会切换到192.168.1.202上面去

※开启192.168.1.201上的keepalived,关闭192.168.1.202上的keepalived,看是否能自动切换,正常情况下VIP又会属于192.168.1.201

注:keepalived切换速度还是非常块的,整个切换过程只需1-3秒

● MySQL故障转移测试

※在192.168.1.201上关闭MySQL服务,看VIP是否会切换到192.168.1.202上

※开启192.168.1.201上的MySQL和keepalived,然后关闭192.168.1.202上的MySQL,看VIP是否会切换到192.168.1.201上

下面是用windows客户端连接的MySQL的VIP,在切换时我执行了一个MySQL查询命令,从执行show databases到显示出结果时间为3-5秒(大家可以看到上面有个错误提示,不过不用担心,因为我们的keepalived切换大概为3秒左右,这3秒左右VIP是谁都不属于的)

MySQL> show databases;

ERROR 2006 (HY000): MySQL server has gone away

No connection. Trying to reconnect...

Connection id: 592

Current database: *** NONE ***



+--------------------+

| Database |

+--------------------+

| information_schema |

| MySQL |

| test |

+--------------------+

3 rows in set (9.01 sec)

后话:世间万事万物,都不具备绝对的完美,就像上面的MySQL-HA一样,keepalived只能做到对3306的健康检查,但是做不到比如像MySQL复制中的slave-SQL、slave-IO进程的检查。所以要想做到一些细致的健康检查,还得需要借助额外的监控工具,比如nagios,然后用nagios实现短信、邮件报警,从而能够有效地解决问题。

 

mysql> GRANT REPLICATION SLAVE ON *.*

-> TO 'repl'@'%.mydomain.com' IDENTIFIED BY 'slavepass';

如果你没有备份主服务器,这里是一个创建备份的快速程序。所有步骤都应该在主服务器主机上执行。

 

1. 发出该语句:

 

mysql> FLUSH TABLES WITH READ LOCK;

2. 仍然加锁时,执行该命令(或它的变体):

 

shell> tar zcf /tmp/backup.tar.gz /var/lib/mysql

3. 发出该语句并且确保记录了以后用到的输出:

 

mysql>SHOW MASTER STATUS;

4. 释放锁:

 

mysql> UNLOCK TABLES;

一个可选择的方法是,转储主服务器的SQL来代替前面步骤中的二进制复制。要这样做,你可以在主服务器上使用mysqldump --master-data,以后装载SQL转储到到你的从服务器。