利用keepalived构建高可用MySQL-HA
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：CentOS5.4
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: 4Warnings: 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>grantreplicationslaveon*.*to'replication'@'%'identifiedby'replication';
QueryOK,0rowsaffected(0.00sec)
MySQL>showmasterstatus;
+------------------+----------+--------------+------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|
+------------------+----------+--------------+------------------+
|MySQL-bin.000003|374|||
+------------------+----------+--------------+------------------+
1rowinset(0.00sec)
在192.168.1.202上将192.168.1.201设为自己的主服务器
MySQL>changemastertomaster_host='192.168.1.201',master_user='replication',master_password='replication',master_log_file='MySQL-bin.000003',master_log_pos=374;
QueryOK,0rowsaffected(0.05sec)
MySQL>startslave;
QueryOK,0rowsaffected(0.00sec)
MySQL>showslavestatus\G
***************************1.row***************************
Slave_IO_State:Waitingformastertosendevent
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
1rowinset(0.00sec)
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>grantreplicationslaveon*.*to'replication'@'%'identifiedby'replication';
QueryOK,0rowsaffected(0.00sec)
MySQL>showmasterstatus;
+------------------+----------+--------------+------------------+
|File|Position|Binlog_Do_DB|Binlog_Ignore_DB|
+------------------+----------+--------------+------------------+
|MySQL-bin.000003|374|||
+------------------+----------+--------------+------------------+
1rowinset(0.00sec)
在192.168.1.201上，将192.168.1.202设为自己的主服务器
MySQL>changemastertomaster_host='192.168.1.202',master_user='replication',master_password='replication',master_log_file='MySQL-bin.000003',master_log_pos=374;
QueryOK,0rowsaffected(0.05sec)
MySQL>startslave;
QueryOK,0rowsaffected(0.00sec)
MySQL>showslavestatus\G
***************************1.row***************************
Slave_IO_State:Waitingformastertosendevent
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
1rowinset(0.00sec)
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
#tarzxvfkeepalived-1.1.20.tar.gz
#cdkeepalived-1.1.20
#./configure--prefix=/usr/local/keepalived--with-kernel-dir=/usr/src/kernels/2.6.18-164.el5-i686
（注意这里2.6.18-164.el5-i686版本自己到服务器的/usr/src/kernels目录下去看，写当前服务器中存在的版本）
#make&&makeinstall
[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
root4101 0.3 0.135828 632 ? Ss15:41 0:00/usr/local/keepalived/sbin/keepalived -D
root4102 0.7 0.439988 1620 ? S15:41 0:00/usr/local/keepalived/sbin/keepalived -D
root4103 0.5 0.339988 1092 ? S15:41 0:00/usr/local/keepalived/sbin/keepalived -D
root4106 0.0 0.261136 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
!ConfigurationFileforkeepalived
global_defs{
notification_email{
luwenju@live.cn
}
notification_email_fromluwenju@live.cn
smtp_server127.0.0.1
smtp_connect_timeout30
router_idMySQL-ha
}
vrrp_instanceVI_1{
stateBACKUP#两台配置此处均是BACKUP
interfaceeth0 #网卡，可使用ifconfig查看
virtual_router_id51
priority100#优先级，另一台改为90
advert_int1
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_typePASS
auth_pass1111
}
virtual_ipaddress{
192.168.1.200
}
}
virtual_server192.168.1.2003306{
delay_loop2#每个2秒检查一次real_server状态
lb_algowrr#LVS算法
lb_kindDR#LVS模式
persistence_timeout60#会话保持时间
protocolTCP
real_server192.168.1.2013306{
weight3
notify_down/usr/local/MySQL/bin/MySQL.sh#检测到服务down后执行的脚本
TCP_CHECK{
connect_timeout10#连接超时时间
nb_get_retry3#重连次数
delay_before_retry3#重连间隔时间
connect_port3306#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|grepkeepalived
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
#tarzxvfkeepalived-1.1.20.tar.gz
#cdkeepalived-1.1.20
#./configure--prefix=/usr/local/keepalived--with-kernel-dir=/usr/src/kernels/2.6.18-164.el5-i686
#make&&makeinstall
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
!ConfigurationFileforkeepalived
global_defs{
notification_email{
luwenju@live.cn
}
notification_email_fromluwenju@live.cn
smtp_server127.0.0.1
smtp_connect_timeout30
router_idMySQL-ha
}
vrrp_instanceVI_1{
stateBACKUP
interfaceeth0
virtual_router_id51
priority90
advert_int1
authentication{
auth_typePASS
auth_pass1111
}
virtual_ipaddress{
192.168.1.200
}
}
virtual_server192.168.1.2003306{
delay_loop2
lb_algowrr
lb_kindDR
persistence_timeout60
protocolTCP
real_server192.168.1.2023306{
weight3
notify_down/usr/local/MySQL/bin/MySQL.sh
TCP_CHECK{
connect_timeout10
nb_get_retry3
delay_before_retry3
connect_port3306
}
}
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|grepkeepalived
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>grantallprivilegeson*.*to'root'@'%'identifiedby'123456';
QueryOK,0rowsaffected(0.00sec)
MySQL>flushprivileges;
QueryOK,0rowsaffected(0.00sec)
使用客户端登录VIP测试
C:\MySQL\bin>MySQL.exe-uroot-p123456-h192.168.1.200-P3306
WelcometotheMySQLmonitor.Commandsendwith;or\g.
YourMySQLconnectionidis224
Serverversion:5.0.89-logSourcedistribution
Type'help;'or'\h'forhelp.Type'\c'toclearthecurrentinputstatement.
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>showdatabases;
ERROR2006(HY000):MySQLserverhasgoneaway
Noconnection.Tryingtoreconnect...
Connectionid:592
Currentdatabase:***NONE***
+--------------------+
|Database|
+--------------------+
|information_schema|
|MySQL|
|test|
+--------------------+
3rowsinset(9.01sec)
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。
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