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使用keepalived构建高可用mysql

时间:2021-07-01 10:21:17 帮助过:12人阅读

http://bbs.linuxtone.org/thread-8172-1-1.html 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

http://bbs.linuxtone.org/thread-8172-1-1.html


关于mysql-HA,目前有多种解决方案,比如heartbeatdrbdmmm、共享存储,但是它们各有优缺点。heartbeatdrbd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mysqlmaster+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-VIP192.168.1.200

Mysql-master1192.168.1.201

Mysql-master2192.168.1.202



OS版本:CentOS 5.4

Mysql版本:5.0.89

Keepalived版本:1.1.20




一、mysqlmaster-master配置

1、修改mysql配置文件

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mysqlserver-ID不能一样,默认情况下两台mysqlserverID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

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)



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:
Replcate_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

192.168.1.202上新建授权用户

mysql> grant replication slave on *.* to'replication'@'%' identified by 'replication';


mysql> show master status;

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

| File

| Position | Binlog_Do_DB |Binlog_Ignore_DB |

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

| mysql-bin.000003 |
374 |
|
|

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

1 row in set (0.00 sec)

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


mysql> change master tomaster_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;


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_B:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:

Replicate_Wid_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)


4mysql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mysqlmysql同步在此不再演示





二、keepalived安装及配置


1192.168.1.201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


配置keepalived

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 keepalivedglobal_defs {
notification_email {
luwenju@live.cn
}
notification_email_from luwenju@live.cn
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

pkillkeepalived

#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pkill keepalived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mysqlIP+VIP,而不是两台mysqlIP+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
mysqlVIP,这时候mysqlVIP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





2192.168.1.202keepalived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 {
luwenju@live.cn
}
notification_email_from luwenju@live.cn
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_timeout60
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
pkillkeepalived

#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windows,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。在此再次感谢
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