描述了使用keepalived施工可用性MySQL-HA，两个保证MySQL数据一致性，然后，keepalived虚拟IP，经keepalived内置的在线监测功能来实现MySQL。
AD：
关于MySQL-HA，眼下有多种解决方式。比方heartbeat、drbd、mmm、共享存储，可是它们各有优缺点。
heartbeat、drbd配置较为复杂，须要自己写脚本才干实现MySQL自己主动切换，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，生产环境中非常少有人用，且mmm 管理端须要单独执行一台server上，要是想实现高可用，就得对mmm管理端做HA，这样无疑又添加了硬件开支；对于共享存储，个人认为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式，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故障时自己主动切换。
以下。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是怎样实现的，环境拓扑例如以下
MySQL-VIP：192.168.1.90
MySQL-master1：192.168.1.91
MySQL-master2：192.168.1.92
OS版本号：CentOS 5.4
MySQL版本号：5.0.89
Keepalived版本号：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、改动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，需将当中一台改动为2就可以
2、将192.168.1.201设为192.168.1.202的主server
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server
;
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server
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server
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同步測试
如上述均正确配置。如今不论什么一台MySQL上更新数据都会同步到还有一台MySQL，MySQL同步在此不再演示
二、keepalived安装及配置
1、192.168.1.201server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
（注意这里2.6.18-164.el5-i686版本号自己到server的/usr/src/kernels文件夹下去看，写当前server中存在的版本号）
#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文件夹下找配置文件
#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 #两台配置此处均是BACKUP
interface eth0 #网卡，可使用ifconfig查看
virtual_router_id 51
priority 100 #优先级，还有一台改为90
advert_int 1
nopreempt #不抢占，仅仅在优先级高的机器上设置就可以。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 {
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 #检測到服务down后运行的脚本
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
}
}
编写检測服务down后所要运行的脚本
#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。我们能够看到。脚本就一个命令，通过pkillkeepalived强制杀死keepalived进程，从而实现了MySQL故障自己主动转移。另外，我们不用操心两个MySQL会同一时候提供数据更新操作，由于每台MySQL上的keepalived的配置里面仅仅有本机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
測试
找一台局域网PC，然后去ping MySQL的VIP，这时候MySQL的VIP是能够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 {
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_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
}
}
编写检測服务down后所要运行的脚本
#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
測试
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、測试
MySQL远程登录測试
我们找一台安装有MySQLclient的windows。然后登录VIP，看能否登录，在登录之两台MySQLserver都要授权同意从远程登录
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client登录VIP測试
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故障转移測试
※在windowsclient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，看能否自己主动切换。正常情况下VIP又会属于192.168.1.201
注：keepalived切换速度还是很块的。整个切换过程仅仅需1-3秒
● MySQL故障转移測试
※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
以下是用windowsclient连接的MySQL的VIP。在切换时我运行了一个MySQL查询命令，从运行show databases到显示出结果时间为3-5秒（大家能够看到上面有个错误提示，只是不用操心，由于我们的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仅仅能做到对3306的健康检查，可是做不到比方像MySQL复制中的slave-SQL、slave-IO进程的检查。所以要想做到一些仔细的健康检查，还得须要借助额外的监控工具，比方nagios。然后用nagios实现短信、邮件报警，从而可以有效地解决这个问题。
mysql> GRANT REPLICATION SLAVE ON *.*
-> TO 'repl'@'%.mydomain.com' IDENTIFIED BY 'slavepass';
假设你没有备份主server。这里是一个创建备份的高速程序。全部步骤都应该在主server主机上运行。
1. 发出该语句：
mysql> FLUSH TABLES WITH READ LOCK。
2. 仍然加锁时，运行该命令（或它的变体）：
shell> tar zcf /tmp/backup.tar.gz /var/lib/mysql
3. 发出该语句而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server的SQL来取代前面步骤中的二进制复制。
要这样做，你能够在主server上使用mysqldump --master-data。以后装载SQL转储到到你的从server。
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