MySQL主主复制技术+Keepalived
MM+keepalived
简介:
双主配合keepalived这种架构设计,也是基于主从复制的原理而搭建的。
使用MySQL主主复制技术+Keepalived是一种简单、便捷的解决方案,在高可用集群环境中,keepalived使用VIP,使用Keepalived自带的服务监控功能和自定义脚本来实现MySQL故障时自动切换,非常灵活。
应用范围:
一般中小型公司都使用这种架构,搭建比较方便简单;
可以采用主从或者主主模式,在 master 节点发生故障后,利用 keepalived 高可用机制实现快速切换到 slave 节点。原来的从库变成新的主库。
个人建议:
一定要完善好切换脚本,keepalived 的切换机制要合理,避免切换不成功的现象发生。
从库的配置尽快要与主库一致,不能太次;避免主库宕机发生切换,新的主库(原来的从库)影响线上业务进行。
对于延迟的问题,在这套架构中,也不能避免。可以使用 mysql 5.7 中增强半同步完成。也可以改变架构使用 PXC,完成时时同步功能,基本上没有延迟;
keepalived 无法解决脑裂的问题,因此在进行服务异常判断时,可以修改我们的判断脚本,通过对第三方节点补充检测来决定是否进行切换,可降低脑裂问题产生的风险。
采用 keepalived 这个架构,在设置两节点状态时,都要设置成不抢占模式,都是 backup 状态,通过优先级,来决定谁是主库。避免脑裂,冲突现象发生。
安装好 mysql 需要的一些依赖包;建议配置好 yum 源,用 yum 安装 keepalived 即可。
搭建架构之前理清思路:
首先需要装有两台mysql的数据库服务器,两者之间互为主从模式,都可读写。其实就只有一台服务器A负责数据的写入工作,而另一台服务器B作为我们的备用数据库;
安装keepalived的软件包,个人建议使用yum安装就可以,很方便。当然我们要知道yum安装之后的软件路径在什么位置。
整理好keepalived的配置文件,理清keepalived的三种状态信息。还要准备一个监控MySQL的脚本,便于检测到宕机顺利发生切换的过程。
所有提供服务的从服务器与备用服务器B进行主从同步。----双主从库模式
在两台服务器A和B,当配置keepalived的参数文件中,要注意两台机器都要采用backup这种状态,就是nopreempt这种非抢占模式,避免出现冲突,发生脑裂现象。
架构图展示:
实验部署环境介绍:
192.168.56.100 主 ---master1
192.168.56.101 备库---master2
都是干净环境没有任何数据
VIP:192.168.56.111
MySQL数据库版本5.7.14,采用GTID模式搭建主从环境
注意事项:
两台机器的防火墙必须是关闭状态。
两台MySQL数据库配置文件中server-id绝对不能一样,要不会报1593这个主从同步的错误,导致搭建不成功。
实战开始:
首先先要搭建两台MySQL数据库为互为主从的架构模式。
添加主从同步账号:
在192.168.56.100:
grant replication slave on *.* to 'bak'@'192.168.56.%' identified by '123456';
flush privileges;
在192.168.56.101:
grant replication slave on *.* to 'bak'@'192.168.56.%' identified by '123456';
flush privileges;
配置同步信息:
先在192.168.56.101上:
CHANGE MASTER TO MASTER_HOST='192.168.56.100',MASTER_USER='bak',MASTER_PASSWORD='123456',master_auto_position=1;
打开主从同步开关:
start slave;
查看主从同步状态:
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[email protected] 10:49: [(none)]> show slave status\G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.56.100
Master_User: bak
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mybinlog.000005
Read_Master_Log_Pos: 234
Relay_Log_File: node2-relay-bin.000010
Relay_Log_Pos: 365
Relay_Master_Log_File: mybinlog.000005
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: 234
Relay_Log_Space: 572
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
Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3306100
Master_UUID: 913cc1d6-771a-11e7-8fe1-080027f1fd08
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set: 5a668126-771d-11e7-b14c-08002783b39d:1-2,
913cc1d6-771a-11e7-8fe1-080027f1fd08:1-13 Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
|
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从库两个工作的线程:IO,SQL都为 yes ,代表同步搭建成功
Slave_IO_Running: Yes Slave_SQL_Running: Yes |
再在192.168.56.100上:
配置主从同步信息:
CHANGE MASTER TO MASTER_HOST='192.168.56.101',MASTER_USER='bak',MASTER_PASSWORD='123456',master_auto_position=1;
开启主从开关:
start slave;
查看主从同步状态:
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[email protected] 10:49: [(none)]> show slave status\G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.56.101
Master_User: bak
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mybinlog.000005
Read_Master_Log_Pos: 234
Relay_Log_File: node1-relay-bin.000008
Relay_Log_Pos: 365
Relay_Master_Log_File: mybinlog.000005
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: 234
Relay_Log_Space: 572
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
Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3306101
Master_UUID: 5a668126-771d-11e7-b14c-08002783b39d
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set: 5a668126-771d-11e7-b14c-08002783b39d:1-2,
913cc1d6-771a-11e7-8fe1-080027f1fd08:1-13 Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
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同理 Slave_IO_Running: Yes Slave_SQL_Running: Yes 从库两个工作的线程:IO,SQL都为 yes ,代表同步搭建成功。
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分别两台机器上安装keepalived的软件包,可以使用yum安装方式
yum -y install keepalived;
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Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile * c6-media:
file : ///media/CentOS/repodata/repomd .xml: [Errno 14] Could not open /read file : ///media/CentOS/repodata/repomd .xml
Trying other mirror. file : ///media/cdrecorder/repodata/repomd .xml: [Errno 14] Could not open /read file : ///media/cdrecorder/repodata/repomd .xml
Trying other mirror. c6-media | 4.0 kB 00:00 ... Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package keepalived.x86_64 0:1.2.7-3.el6 will be installed --> Finished Dependency Resolution Dependencies Resolved ====================================================================================================================================== Package Arch Version Repository Size
====================================================================================================================================== Installing: keepalived x86_64 1.2.7-3.el6 c6-media 174 k
Transaction Summary ====================================================================================================================================== Install 1 Package(s) Total download size: 174 k Installed size: 526 k Downloading Packages: Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : keepalived-1.2.7-3.el6.x86_64 1 /1 Verifying : keepalived-1.2.7-3.el6.x86_64 1 /1 Installed: keepalived.x86_64 0:1.2.7-3.el6
Complete! |
证明keepalived软件已经存在:
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rpm -qa| grep keepalived
keepalived-1.2.7-3.el6.x86_64 |
在两台机器上分别配置检测MySQL数据库的脚本:
首先进入到yum安装后的软件目录下:
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cd /etc/keepalived
vim check_mysql.py |
脚本通过查看MySQL进程的存在,和是否可以连接,来判断MySQL的状态
(这里只展现了脚本中判断的一部分)
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def existMySQL(self):
cmd= "ps -ef | egrep -i \"mysqld\" | grep %s | egrep -iv \"mysqld_safe\" | grep -v grep | wc -l" % self.dbport
mysqldNum = os.popen(cmd). read ()
cmd = "netstat -tunlp | grep \":%s\" | wc -l" % self.dbport
mysqlPortNum= os.popen(cmd). read ()
#print mysqldNum, mysqlPortNum
if ( int(mysqldNum) <= 0):
print "error"
return 1
if ( int(mysqldNum) > 0 and mysqlPortNum <= 0):
return 1
return 0
def connect(self):
# print "in db conn"
# print "host : %s, port: %d, user: %s, password: %s" % (self.dbhost, self.dbport, self.dbuser, self.dbpassword) try:
self.conn=MySQLdb.connect(host= "%s" %self.dbhost, port=self.dbport,user= "%s" %dbuser, passwd = "%s" %self.dbpassword)
except Exception, e:
# print " Error" print e
return 1
return 0
def disconnect(self):
if (self.conn):
self.conn.close()
self.conn = None
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在两台机器上修改keepalived的配置文件:
192.168.56.100上面
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vim /etc/keepalived/keepalived .conf
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vrrp_instance VI_100 { state BACKUP
nopreempt
interface eth0
virtual_router_id 100
priority 100
advert_int 5
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
vs_mysql_100
}
virtual_ipaddress {
192.168.56.111
}
} |
192.168.56.101上面:
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vrrp_instance VI_101 { state BACKUP
nopreempt
interface eth0
virtual_router_id 100
priority 90
advert_int 5
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
vs_mysql_101
}
virtual_ipaddress {
192.168.56.111
}
} |
总结:可以看到两台机器的state都是backup并且都是非抢占模式nopreempt,通过优先级的高低来决定谁是主库。(这里192.168.56.100是主)还有注意virtual_router_id(虚拟路由id)要保持一致。
接下来可以启动两台机器的keepalived进程:
192.168.56.100:
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[[email protected] keepalived] # /etc/init.d/keepalived start
Starting keepalived: [ OK ] |
观察日志中信息的变化:
cat /var/log/messages
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Aug 3 10:52:17 node1 Keepalived_vrrp[6760]: Opening file '/etc/keepalived/keepalived.conf' .
Aug 3 10:52:17 node1 Keepalived_vrrp[6760]: Configuration is using : 62711 Bytes Aug 3 10:52:17 node1 Keepalived_vrrp[6760]: Using LinkWatch kernel netlink reflector... Aug 3 10:52:17 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) Entering BACKUP STATE Aug 3 10:52:17 node1 Keepalived_vrrp[6760]: VRRP sockpool: [ifindex(2), proto(112), fd(11,12)] Aug 3 10:52:17 node1 Keepalived_healthcheckers[6759]: Opening file '/etc/keepalived/keepalived.conf' .
Aug 3 10:52:17 node1 Keepalived_healthcheckers[6759]: Configuration is using : 4431 Bytes Aug 3 10:52:17 node1 Keepalived_healthcheckers[6759]: Using LinkWatch kernel netlink reflector... Aug 3 10:52:18 node1 Keepalived_vrrp[6760]: VRRP_Script(vs_mysql_100) succeeded Aug 3 10:52:33 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) Transition to MASTER STATE Aug 3 10:52:38 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) Entering MASTER STATE Aug 3 10:52:38 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) setting protocol VIPs. Aug 3 10:52:38 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) Sending gratuitous ARPs on eth0 for 192.168.56.111
Aug 3 10:52:38 node1 Keepalived_healthcheckers[6759]: Netlink reflector reports IP 192.168.56.111 added Aug 3 10:52:43 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) Sending gratuitous ARPs on eth0 for 192.168.56.111
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可以看到它从backup状态切换到master的状态了,并且发送了一个广播协议,证明192.168.56.111已经在本台机器上面,其他机器不要再使用了。
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[[email protected] keepalived] # ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link /loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1 /8 scope host lo
inet6 ::1 /128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link /ether 08:00:27:f1:fd:08 brd ff:ff:ff:ff:ff:ff
inet 192.168.56.100 /24 brd 192.168.56.255 scope global eth0
inet 192.168.56.111 /32 scope global eth0
inet6 fe80::a00:27ff:fef1:fd08 /64 scope link
valid_lft forever preferred_lft forever
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192.168.56.101:
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[[email protected] ~] # /etc/init.d/keepalived start
Starting keepalived: [ OK ] |
cat /var/log/messages
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Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Interface queue is empty Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Netlink reflector reports IP 192.168.56.101 added Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Netlink reflector reports IP fe80::a00:27ff:fe83:b39d added Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Registering Kernel netlink reflector Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Registering Kernel netlink command channel
Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Opening file '/etc/keepalived/keepalived.conf' .
Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Configuration is using : 4561 Bytes Aug 3 10:53:28 node2 Keepalived_healthcheckers[8111]: Using LinkWatch kernel netlink reflector... Aug 3 10:53:28 node2 Keepalived_vrrp[8112]: Opening file '/etc/keepalived/keepalived.conf' .
Aug 3 10:53:28 node2 Keepalived_vrrp[8112]: Configuration is using : 62577 Bytes Aug 3 10:53:28 node2 Keepalived_vrrp[8112]: Using LinkWatch kernel netlink reflector... Aug 3 10:53:28 node2 Keepalived_vrrp[8112]: VRRP_Instance(VI_101) Entering BACKUP STATE Aug 3 10:53:28 node2 Keepalived_vrrp[8112]: VRRP sockpool: [ifindex(2), proto(112), fd(12,13)] Aug 3 10:53:28 node2 Keepalived_vrrp[8112]: VRRP_Script(vs_mysql_101) succeeded |
这台服务器就是正常的backup状态,时刻准备着接管主库的服务。
模拟一下主库宕机的故障切换:
主库192.168.56.100上面执行关闭MySQL服务操作:
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mysqladmin -uroot -proot123 shutdown
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这时再查看一下keepalived日志的情况:
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cat /var/log/messages
Aug 3 11:04:17 node1 Keepalived_vrrp[6760]: VRRP_Script(vs_mysql_100) failed Aug 3 11:04:18 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) Entering FAULT STATE Aug 3 11:04:18 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) removing protocol VIPs. Aug 3 11:04:18 node1 Keepalived_healthcheckers[6759]: Netlink reflector reports IP 192.168.56.111 removed Aug 3 11:04:18 node1 Keepalived_vrrp[6760]: VRRP_Instance(VI_100) Now in FAULT state
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已经把vip removed了,并且keepalived的状态变成了fault
在备库192.168.56.101上面查看日志:
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cat /var/log/messages
Aug 3 11:04:29 node2 Keepalived_vrrp[8112]: VRRP_Instance(VI_101) Transition to MASTER STATE Aug 3 11:04:34 node2 Keepalived_vrrp[8112]: VRRP_Instance(VI_101) Entering MASTER STATE Aug 3 11:04:34 node2 Keepalived_vrrp[8112]: VRRP_Instance(VI_101) setting protocol VIPs. Aug 3 11:04:34 node2 Keepalived_vrrp[8112]: VRRP_Instance(VI_101) Sending gratuitous ARPs on eth0 for 192.168.56.111
Aug 3 11:04:34 node2 Keepalived_healthcheckers[8111]: Netlink reflector reports IP 192.168.56.111 added Aug 3 11:04:39 node2 Keepalived_vrrp[8112]: VRRP_Instance(VI_101) Sending gratuitous ARPs on eth0 for 192.168.56.111
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备库已经从backup状态切换成master状态了。并且VIP(192.168.56.111)已经切换过来。
查看ip地址:
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[[email protected] ~] # ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link /loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1 /8 scope host lo
inet6 ::1 /128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link /ether 08:00:27:83:b3:9d brd ff:ff:ff:ff:ff:ff
inet 192.168.56.101 /24 brd 192.168.56.255 scope global eth0
inet 192.168.56.111 /32 scope global eth0
inet6 fe80::a00:27ff:fe83:b39d /64 scope link
valid_lft forever preferred_lft forever
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主备库切换成功。