Mysql双向复制+KeepAlived：配置mysql的高可用
说明：
此文章是借鉴好朋友的文档 http://sunys.blog.51cto.com/8368410/1639820完成的
主从同步的原理：http://732233048.blog.51cto.com/9323668/1616386
环境：
mysql的版本：mysql-5.6.22
系统：centos6.4
master：192.168.186.132
slave：192.168.186.133
vip: 192.168.186.140 #虚拟ip，web服务器连接的ip
防火墙和selinux关闭
步骤：
配置mysql的单向复制：
注意:mysql的安装步骤省略
master： #开启二进制日志文件
vi /usr/local/mysql/my.cnf
在[mysqld]下添加：
server-id = 1
log-bin = /opt/mysql/binlog/mysql-binlog #二进制日志文件路径随便设置，最好单独放在一个目录下
/etc/init.d/mysqld restart #服务必须要重启restart，二进制日志才会生效
slave：
vi /usr/local/mysql/my.cnf
在[mysqld]下添加：
server-id = 2
/etc/init.d/mysqld restart #必须要用restart，用reload不生效
master： #对slave授权
mysql -uroot -p123456
grant replication slave on *.* to 'slave'@'192.168.186.133' identified by '123456';
flush privileges;
master： #备份数据
mysql -uroot -p123456
flush tables with read lock; #锁表，只读
show master status; #查看此时的binlog位置和pos值，这个要记录下来
+---------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+---------------------+----------+--------------+------------------+-------------------+
| mysql-binlog.000044 | 412 | | | |
+---------------------+----------+--------------+------------------+-------------------+
打开另外一个终端：mysqldump -u root -p123456 --all-databases > /tmp/mysqldump.sql
回到之前终端：unlock tables; #解表
注意：锁表--查看--备份--解表 顺序要注意
scp /tmp/mysqldump.sql 192.168.186.133:/tmp/ #把备份数据拷到slave
slave： #导入数据
mysql -uroot -p123456 < /tmp/mysqldump.sql
slave： #开始同步
mysql -uroot -p123456
change master to master_host='192.168.186.132',master_user='slave',master_password='123456',master_log_file='mysql-binlog.000044',master_log_pos=412,master_port=3306;
start slave;
show slave status\G; #查看是否成功，如下：出现两个Yes则成功
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.186.132
Master_User: slave
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-binlog.000044
Read_Master_Log_Pos: 412
Relay_Log_File: scj-relay-bin.000002
Relay_Log_Pos: 286
Relay_Master_Log_File: mysql-binlog.000044
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
注意：
第一个Yes：与连接相关（若为no，查看防火墙，selinux，是否授权grant等等）
第二个Yes：与数据相关（若为no，查看数据是否拷过去，配置文件是否配置server-id参数）
单向主从同步：不能在从机进行任何写操作，所有写操作都是在主机进行（注意：经过不断测试：在从库执行写操作，主从同步并不会断掉，只是从库数据不会同步到主库而已，且主从同步仍可正常工作）
若从机出现问题（如：突然关机），恢复正常后会继续同步主库数据，一般不会出现主从断掉的情况
如下图：
如上图：如果我们没有执行图中的这几步，而是跳过直接在slave上执行change master to，从库会从000044这个文件里的412开始同步主库上的数据，这样的话：主从同步仍可建立，只是主库与从库上的数据不一致，从库只有pos值为412之后的数据
配置mysql的双向复制：（注意：在单向复制的基础上进行）
slave： #开启二进制日志文件
vi /usr/local/mysql/my.cnf
在[mysqld]下添加：
log-bin = /opt/mysql/binlog/mysql-binlog #保证两台主机上的这个文件名字一致
/etc/init.d/mysqld restart
master： #授权
grant replication slave on *.* to 'slave'@'192.168.186.132' identified by '123456'; #在master上执行授权语句，会同步到slave上的（实质：slave给master授权）
flush privileges;
slave： #查看二进制日志和pos信号值，记录下来
show master status;
+---------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+---------------------+----------+--------------+------------------+
| mysql-binlog.000001 | 106 | | |
+---------------------+----------+--------------+------------------+
master： #开始同步
change master to master_host='192.168.186.133',master_user='slave',master_password='123456',master_log_file='mysql-binlog.000001',master_log_pos=106;
start slave;
show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.186.133
Master_User: slave
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-binlog.000001
Read_Master_Log_Pos: 106
Relay_Log_File: mysqld-relay-bin.000002
Relay_Log_Pos: 254
Relay_Master_Log_File: mysql-binlog.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
注意：
双向主从：当主库（主1）出现问题，则由从库（主2）接过任务继续对外提供服务，等到主库恢复正常后会去同步从库上的数据，达到主从数据一致，且主从同步仍正常使用
搭建keepalived实现主从自动切换：
原理：
keepalived用来解决单点故障，提供vrrp（虚拟路由冗余协议）以及healthcheck功能，提供一个vip虚拟ip；keepalived的作用是检测服务器的状态，当其中一台服务器出现问题，则将它从组中剔除，恢复后再将它加进来
参考文档：
http://blog.csdn.net/jibcy/article/details/7826158
http://bbs.nanjimao.com/thread-855-1-1.html
注意：以下步骤在两台mysql服务器上都要操作
安装keepalived：
cd /usr/local/src/
wget http://www.keepalived.org/software/keepalived-1.2.15.tar.gz
tar -zxf keepalived-1.2.15.tar.gz
cd keepalived-1.2.15
./configure --prefix=/usr/local/keepalived
make
make install
拷贝文件：
cp -a /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp -a /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived/
cp -a /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp -a /usr/local/keepalived/sbin/keepalived /usr/sbin/
注意：
/etc/sysconfig/keepalived 和 /etc/keepalived/keepalived.conf 的路径一定要正确，因为在执行/etc/init.d/keepalived这个启动脚本时，会读取/etc/sysconfig/keepalived 和 /etc/keepalived/keepalived.conf 这两个文件
修改配置文件：
master： #修改master配置文件
mv /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.old
vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
}
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id mysql
}
vrrp_instance VI_1 {
state master
interface eth0
virtual_router_id 51
priority 150
advert_int 1
#nopreempt
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.186.140
}
}
virtual_server 192.168.186.140 3306 {
delay_loop 6
lb_algo wrr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 192.168.186.132 3306 {
weight 3
notify_down /etc/keepalived/killkeepalived.sh
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 3306
}
}
}
slave： #修改slave配置文件
mv /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.old
vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
}
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id mysql
}
vrrp_instance VI_1 {
state backup
interface eth0
virtual_router_id 51
priority 100
advert_int 1
#nopreempt
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.186.140
}
}
virtual_server 192.168.186.140 3306 {
delay_loop 6
lb_algo wrr
lb_kind DR
persistence_timeout 50
protocol TCP
real_server 192.168.186.133 3306 {
weight 3
notify_down /etc/keepalived/killkeepalived.sh
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 3306
}
}
}
vi /etc/keepalived/killkeepalived.sh #创建脚本
#!/bin/sh pkill keepalived
注意：此脚本的作用：
keepalived子进程会时刻监控本机的mysql服务，若mysql服务出现问题（如:stop）,则会去执行此脚本，把keepalived进程杀掉（正常情况master会时刻发送vrrp通信给backup，当master出现问题（如：keepalived进程停掉），backup一段时间内接受不到master发来的vrrp信息，则slave会转变为master，接管任务继续对外提供服务）
千万不要把killkeepalived.sh这个脚本放到/var/run/mysqld/这个目录下，否则每次开机都会把这个脚本删掉
chmod 755 /etc/keepalived/killkeepalived.sh #加执行权限
chkconfig keepalived on #设置开机自动启动
查看是否绑定vip：
master： #查看master日志文件
/etc/init.d/keepalived start
tail -f /var/log/messages
May 8 17:08:01 localhost Keepalived[10191]: Starting Keepalived v1.2.15 (05/07,2015)
May 8 17:08:01 localhost Keepalived[10192]: Starting Healthcheck child process, pid=10194
May 8 17:08:01 localhost Keepalived[10192]: Starting VRRP child process, pid=10195
May 8 17:08:01 localhost Keepalived_vrrp[10195]: Netlink reflector reports IP 192.168.186.132 added
May 8 17:08:01 localhost Keepalived_vrrp[10195]: Netlink reflector reports IP fe80::20c:29ff:fec7:fd75 added
May 8 17:08:01 localhost Keepalived_vrrp[10195]: Registering Kernel netlink reflector
May 8 17:08:01 localhost Keepalived_vrrp[10195]: Registering Kernel netlink command channel
May 8 17:08:01 localhost Keepalived_vrrp[10195]: Registering gratuitous ARP shared channel
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Netlink reflector reports IP 192.168.186.132 added
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Netlink reflector reports IP fe80::20c:29ff:fec7:fd75 added
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Registering Kernel netlink reflector
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Registering Kernel netlink command channel
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Opening file '/etc/keepalived/keepalived.conf'.
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Configuration is using : 11034 Bytes
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Using LinkWatch kernel netlink reflector...
May 8 17:08:01 localhost Keepalived_healthcheckers[10194]: Activating healthchecker for service [192.168.186.132]:3306
May 8 17:08:03 localhost Keepalived_vrrp[10195]: Opening file '/etc/keepalived/keepalived.conf'.
May 8 17:08:03 localhost Keepalived_vrrp[10195]: Configuration is using : 37169 Bytes
May 8 17:08:03 localhost Keepalived_vrrp[10195]: Using LinkWatch kernel netlink reflector...
May 8 17:08:03 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) Entering BACKUP STATE
May 8 17:08:03 localhost Keepalived_vrrp[10195]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]
May 8 17:08:07 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) Transition to MASTER STATE
May 8 17:08:08 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) Entering MASTER STATE
May 8 17:08:08 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) setting protocol VIPs.
May 8 17:08:08 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.186.140
May 8 17:08:08 localhost Keepalived_healthcheckers[10194]: Netlink reflector reports IP 192.168.186.140 added
May 8 17:08:13 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.186.140
slave： #查看slave日志
/etc/init.d/keepalived start
tail -f /var/log/messages
.............
.............
May 8 17:11:42 localhost Keepalived_healthcheckers[10724]: Using LinkWatch kernel netlink reflector...
May 8 17:11:42 localhost Keepalived_healthcheckers[10724]: Activating healthchecker for service [192.168.186.133]:3306
May 8 17:11:42 localhost Keepalived_vrrp[10725]: VRRP_Instance(VI_1) Entering BACKUP STATE
May 8 17:11:42 localhost Keepalived_vrrp[10725]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]
测试：
master： #停掉mysql服务，查看日志
/etc/init.d/mysqld stop
tail -f /var/log/messages
May 8 17:13:32 localhost Keepalived_healthcheckers[10194]: TCP connection to [192.168.186.132]:3306 failed !!!
May 8 17:13:32 localhost Keepalived_healthcheckers[10194]: Removing service [192.168.186.132]:3306 from VS [192.168.186.140]:3306
May 8 17:13:32 localhost Keepalived_healthcheckers[10194]: Executing [/var/run/mysqld/killkeepalived.sh] for service [192.168.186.132]:3306 in VS [192.168.186.140]:3306
May 8 17:13:32 localhost Keepalived_healthcheckers[10194]: Lost quorum 1-0=1 > 0 for VS [192.168.186.140]:3306
May 8 17:13:32 localhost Keepalived_healthcheckers[10194]: Remote SMTP server [0.0.0.0]:25 connected.
May 8 17:13:33 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) sending 0 priority
May 8 17:13:33 localhost Keepalived_vrrp[10195]: VRRP_Instance(VI_1) removing protocol VIPs.
May 8 17:13:33 localhost Keepalived[10192]: Stopping Keepalived v1.2.15 (05/07,2015)
May 8 17:13:37 localhost Keepalived_healthcheckers[10194]: Netlink reflector reports IP 192.168.186.140 removed
slave： #master端停掉mysql服务后查看slave日志
tail -f /var/log/messages
May 8 17:14:02 localhost Keepalived_vrrp[10725]: VRRP_Instance(VI_1) Transition to MASTER STATE
May 8 17:14:03 localhost Keepalived_vrrp[10725]: VRRP_Instance(VI_1) Entering MASTER STATE
May 8 17:14:03 localhost Keepalived_vrrp[10725]: VRRP_Instance(VI_1) setting protocol VIPs.
May 8 17:14:03 localhost Keepalived_vrrp[10725]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.186.140
May 8 17:14:03 localhost Keepalived_healthcheckers[10724]: Netlink reflector reports IP 192.168.186.140 added
May 8 17:14:08 localhost Keepalived_vrrp[10725]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.186.140
注意：
若有一台服务器出现问题，恢复后记得：
不仅把mysql启动起来，还要把keepalived启动起来