评论

收藏

[MySQL] 企业中MySQL高可用集群架构三部曲之MM+keepalived

数据库 数据库 发布于:2021-07-03 21:17 | 阅读数:252 | 评论:0

  各位老铁们,老张与大家又见面了。看到各位在博客里面给我的留言和访问量的情况,我很是欣慰,也谢谢大家对我的认可。我写这些博客,就是想把自己对于MySQL数据库的一些看法和自己平时的实战经验分享出来,我们可以一起探讨,共同进步。也保证今后只要一有空就更新博文,推出更多的干货。
  

  我的学生经常对我说:“张老师,每次我遇到报错,有时还是会百度,但是最烦的是不知道百度哪篇帖子说的是正确的".其实这些呢,都是因为自己还没有对MySQL数据库核心知识的不熟悉,和对技术掌握的不牢固。平时下得功夫还是不到位。我们做技术这个行业,还是需要自己给自己加发条,促使自己每天都要学习一些新的知识。理论配合实验一起,先要学会多问自己几个问题,一个实验多做几遍,可能会得到不同的实验效果。学习知识要踏实下来,学会多做实验总结。我想今后再遇到报错,可能自己就会有一个清晰的解题思路,这个需要一定时间的磨练。
  

  也有人经常问Oracle和MySQL到底有啥区别,其实MySQL数据库上手很简单,难的是后期架构的设计与维护。老张三部曲中第一部曲MHA希望对大家在线上部署方面有帮助。
  

  今儿给大家介绍第二部曲,MM+keepalived的环境部署,我们会多种数据库的架构就可以灵活应用到我们的公司。根据公司业务的不同,选择合适的集群架构。
  

  独家新课程上线>>MySQL体系结构深入剖析及实战DBA视频课程

  

  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:
DSC0000.png

  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。
   DSC0001.png
  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:
root@db 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)
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
root@db 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)
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。
  

  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;
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:
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:
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)
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
  

  在两台机器上修改keepalived的配置文件:
  192.168.56.100上面
vim /etc/keepalived/keepalived.conf
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:
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:
[root@node1 keepalived]# /etc/init.d/keepalived start
Starting keepalived:         [  OK  ]
  观察日志中信息的变化:
  cat /var/log/messages
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
  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。
[root@node1 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
  192.168.56.101:
[root@node2 ~]# /etc/init.d/keepalived start
Starting keepalived:         [  OK  ]
  cat /var/log/messages
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:
mysqladmin -uroot -proot123 shutdown
  这时再查看一下keepalived日志的情况
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
  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:
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
  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:
[root@node2 ~]# 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
  主备库切换成功。
  

  实战演练过程结束,希望对大家学习MySQL高可用集群有帮助。
  

  今后我们可能还会遇到其他的MySQL高可用架构,学习它的时候,先不要忙于搭建,要先弄清原理,整理好实验过程的思路,遇到报错,一步步地去排查。自己的水平也会在这个历练的过程中,得到提升。
  

  今后我们可以一起讨论,在写博的过程中难免可能会有一些笔误,或是想不周全的地方,希望大家谅解。有不对的地方欢迎各位老铁指定。(MySQL高可用集群第二部曲完结
  

  第一步曲直通车>> 企业中MySQL主流高可用架构实战三部曲之MHA
  

  

  


  
关注下面的标签,发现更多相似文章