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MySQL之高可用架构—MHA

    MySQL高可用目前有heartbeat+drbd、MHA、MySQL复制等几种较成熟的方案,heartbeat+drbd的方案可扩展性较差,而且读写都由主服务器负责,从库并不提供读功能,适合于数据增长量不大、一致性要求很高的环境,如银行、金融业等。今天重点讲下MHA的高可用架构。

    MHA是一款优秀的高可用环境下故障切换和主从提升的高可用软件。在MySQL故障切换过程中,MHA能做到0-30秒之内自动完成数据库的故障切换,并且在切换的过程中,最大限度的保证数据的一致性,以达到真正意义上的高可用。MHA高可用建立在MySQL主从复制的基础上,先了解下MySQL复制最常见的两种方式:

  • 异步复制:主库写入并提交事务之后,把记录写进主库二进制日志即返回客户端,主库和从库的数据存在一定的延迟,这样就存在一定的隐患,当主库提交了一个事务,并且写入了二进制日志,而从库尚未得到主库推送的二进制日志时,此时主库宕机,将造成主从服务器的数据不一致。

  • 半同步复制:主库在每次提交事务成功时,并不及时反馈给客户端,而是等待其中一个从库也接收到二进制日志并写入中继日志之后,才返回操作成功给客户端。

    MHA组成:

  • MHA Manager:管理节点,可以单独的部署在一台独立的服务器上,管理多个master-slave集群,也可以部署在一台Slave上。

  • MHA Node:数据节点,运行在每台MySQL服务器上。

MHA Manager会定时探测集群中的master节点,当master出现故障时,它可以自动将最新数据的slave提升为新master,然后将其它所有的slave重新指向新的master。整个故障转移过程对应用程序是完全透明的。

    MHA工作原理:

1)从宕机的master保存二进制日志事件

2)识别含有最新更新的Slave

3) 应用差异的中继日志到其它从服务器

4)应用从master保存的二进制日志事件

5)提升一个新的Slave为master

6)使其它的Slave连接到新的master并复制


示例:MHA高可用架构(如果在内网可以关闭防火墙,否则请开启相应的端口)

Manager:node1:192.168.154.128

Master:node2:192.168.154.156

Slave:node3:192.168.154.130

Slave:node4:192.168.154.154


一 配置主从复制:

1)主节点:

[root@node2 ~]# vim /etc/my.cnf 

innodb_file_per_table=1        #开启独立的表空间

skip_name_resolve              #禁止域名解析

log-bin=master-bin

relay-log=relay-bin

server-id=1

[root@node2 ~]# service mysqld restart

查看二进制日志信息

mysql> show master status;

+-------------------+----------+--------------+------------------+

| File              | Position | Binlog_Do_DB | Binlog_Ignore_DB |

+-------------------+----------+--------------+------------------+

| master-bin.000001 |      106 |              |                  |

+-------------------+----------+--------------+------------------+

1 row in set (0.00 sec)

建立授权用户:

mysql> grant replication slave,replication client on *.* to ‘slave‘@‘192.168.154.%‘ identified by ‘slave‘;

Query OK, 0 rows affected (0.06 sec)


mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)


2)从节点:

[root@node3 ~]# vim /etc/my.cnf 

innodb_file_per_table=1

skip_name_resolve

log-bin=slave-bin

relay-log=relay-bin

server_id=2

read_only=1

relay_log_purge=0

[root@node3 ~]# service mysqld restart


[root@node4 ~]# vim /etc/my.cnf

innodb_file_per_table=1

skip_name_resolve

log-bin=slave-bin

relay-log=relay-bin

server_id=3

read_only=1                    #开启只读模式

relay_log_purge=0              #关闭自动清理中继日志

[root@node4 ~]# service mysqld restart


设置同步:

mysql> change master to master_host=‘192.168.154.156‘,master_user=‘slave‘,master_password=‘slave‘,master_log_file=‘master-bin.000001‘,master_log_pos=106;

Query OK, 0 rows affected (0.03 sec)


mysql> start slave;

Query OK, 0 rows affected (0.01 sec)


mysql> show slave status\G

*************************** 1. row ***************************

               Slave_IO_State: Waiting for master to send event

                  Master_Host: 192.168.154.156

                  Master_User: slave

                  Master_Port: 3306

                Connect_Retry: 60

              Master_Log_File: master-bin.000001

          Read_Master_Log_Pos: 354

               Relay_Log_File: relay-bin.000002

                Relay_Log_Pos: 500

        Relay_Master_Log_File: master-bin.000001

             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: 354

              Relay_Log_Space: 649

              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: 

1 row in set (0.00 sec)


3)在master节点上创建具有管理权限的账号

mysql> grant all on *.* to ‘zwj‘@‘192.168.154.%‘ identified by ‘zwj‘;

Query OK, 0 rows affected (0.00 sec)


二 配置集群间的密钥登陆

在node1上:

[root@node1 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.156

[root@node1 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.130

[root@node1 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.154

[root@node1 ~]# ssh 192.168.154.154 ‘ifconfig‘            #验证

eth0      Link encap:Ethernet  HWaddr 00:0C:29:67:65:ED  

          inet addr:192.168.154.154  Bcast:192.168.154.255  Mask:255.255.255.0

          inet6 addr: fe80::20c:29ff:fe67:65ed/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:26253 errors:0 dropped:0 overruns:0 frame:0

          TX packets:42416 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:23453164 (22.3 MiB)  TX bytes:2514457 (2.3 MiB)

          Interrupt:19 Base address:0x2024 


在node2上:

[root@node2 ~]# ssh-keygen -t rsa

[root@node2 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.128

[root@node2 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.130

[root@node2 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.154


在node3上:

[root@node3 log]# ssh-keygen -t rsa

[root@node3 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.128

[root@node3 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.156

[root@node3 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.154


在node4上:

[root@node4 ~]# ssh-keygen -t rsa

[root@node4 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.128

[root@node4 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.156

[root@node4 ~]# ssh-copy-id -i ./.ssh/id_rsa.pub root@192.168.154.130


三 安装MHA Manager,在node1上:

[root@node1 ~]# yum install perl-DBD-MySQL -y

[root@node1 ~]# tar -zxf mha4mysql-node-0.56.tar.gz 

[root@node1 ~]# cd mha4mysql-node-0.56

[root@node1 mha4mysql-node-0.56]# perl Makefile.PL 

[root@node1 mha4mysql-node-0.56]# make

[root@node1 mha4mysql-node-0.56]# make install


[root@node1 mha4mysql-manager-0.56]# yum install perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-Time-HiRes -y        #安装MHA Manger依赖的perl模块

[root@node1 ~]# tar -zxf mha4mysql-manager-0.56.tar.gz 

[root@node1 ~]# cd mha4mysql-manager-0.56

[root@node1 mha4mysql-manager-0.56]# perl Makefile.PL

[root@node1 mha4mysql-manager-0.56]# make

[root@node1 mha4mysql-manager-0.56]# make install


四 安装MySQL node(在所有MySQL服务器上)

[root@node2 ~]#yum install perl-DBD-MySQL -y

[root@node2 ~]# cd mha4mysql-node-0.56/

[root@node2 mha4mysql-node-0.56]# perl Makefile.PL 

[root@node2 mha4mysql-node-0.56]# make

[root@node2 mha4mysql-node-0.56]# make install 


五 创建工作目录,配置MHA:

[root@node1 ~]# mkdir -pv /etc/masterha

[root@node1 ~]# vim /etc/masterha/appl.cnf

[server default]

user=zwj

password=zwj

manager_workdir=/etc/masterha/appl

manager_log=/etc/masterha/appl/manager.log

remote_workdir=/etc/masterha/appl

ssh_user=root

repl_user=slave

repl_password=slave

ping_interval=1


[server1]

hostname=192.168.154.156


[server2]

hostname=192.168.154.130

candidate_master=1                        #设置为备选的master


[server3]

hostname=192.168.154.154


六 检查SSH连接状态:

[root@node1 ~]# masterha_check_ssh --conf=/etc/masterha/appl.cnf 

Wed May 10 00:12:58 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.

Wed May 10 00:12:58 2017 - [info] Reading application default configuration from /etc/masterha/appl.cnf..

Wed May 10 00:12:58 2017 - [info] Reading server configuration from /etc/masterha/appl.cnf..

Wed May 10 00:12:58 2017 - [info] Starting SSH connection tests..

Wed May 10 00:13:15 2017 - [debug] 

Wed May 10 00:12:59 2017 - [debug]  Connecting via SSH from root@192.168.154.154(192.168.154.154:22) to root@192.168.154.156(192.168.154.156:22)..

Wed May 10 00:13:05 2017 - [debug]   ok.

Wed May 10 00:13:05 2017 - [debug]  Connecting via SSH from root@192.168.154.154(192.168.154.154:22) to root@192.168.154.130(192.168.154.130:22)..

Wed May 10 00:13:15 2017 - [debug]   ok.

Wed May 10 00:13:20 2017 - [debug] 

Wed May 10 00:12:58 2017 - [debug]  Connecting via SSH from root@192.168.154.130(192.168.154.130:22) to root@192.168.154.156(192.168.154.156:22)..

Wed May 10 00:13:11 2017 - [debug]   ok.

Wed May 10 00:13:11 2017 - [debug]  Connecting via SSH from root@192.168.154.130(192.168.154.130:22) to root@192.168.154.154(192.168.154.154:22)..

Wed May 10 00:13:20 2017 - [debug]   ok.

Wed May 10 00:13:35 2017 - [debug] 

Wed May 10 00:12:58 2017 - [debug]  Connecting via SSH from root@192.168.154.156(192.168.154.156:22) to root@192.168.154.130(192.168.154.130:22)..

Wed May 10 00:13:15 2017 - [debug]   ok.

Wed May 10 00:13:15 2017 - [debug]  Connecting via SSH from root@192.168.154.156(192.168.154.156:22) to root@192.168.154.154(192.168.154.154:22)..

Wed May 10 00:13:35 2017 - [debug]   ok.

Wed May 10 00:13:35 2017 - [info] All SSH connection tests passed successfully.


七 检查整个复制环境:

[root@node1 ~]# masterha_check_repl --conf=/etc/masterha/appl.cnf 

...

192.168.154.156(192.168.154.156:3306) (current master)

 +--192.168.154.130(192.168.154.130:3306)

 +--192.168.154.154(192.168.154.154:3306)


Wed May 10 00:33:36 2017 - [info] Checking replication health on 192.168.154.130..

Wed May 10 00:33:36 2017 - [info]  ok.

Wed May 10 00:33:36 2017 - [info] Checking replication health on 192.168.154.154..

Wed May 10 00:33:36 2017 - [info]  ok.

Wed May 10 00:33:36 2017 - [warning] master_ip_failover_script is not defined.

Wed May 10 00:33:36 2017 - [warning] shutdown_script is not defined.

Wed May 10 00:33:36 2017 - [info] Got exit code 0 (Not master dead).


MySQL Replication Health is OK.


八 开启MHA Manager监控:

[root@node1 ~]# nohup masterha_manager --conf=/etc/masterha/appl.cnf > /etc/masterha/appl/manager.log 2>&1 &

[1] 8300

查看MHA Manager监控:

[root@node1 ~]# masterha_check_status --conf=/etc/masterha/appl.cnf 

appl (pid:8300) is running(0:PING_OK), master:192.168.154.156

关闭MHA Manager监控:

[root@node1 ~]# masterha_stop --conf=/etc/masterha/appl.cnf 

Stopped appl successfully.

[1]+  Exit 1                  nohup masterha_manager --conf=/etc/masterha/appl.cnf > /etc/masterha/appl/manager.log 2>&1


九 模拟主库宕机:

[root@node2 ~]# service mysqld stop

Stopping mysqld:                                           [  OK  ]

查看slave(node4),可见master已发生变化,

...

mysql> show slave status\G

*************************** 1. row ***************************

               Slave_IO_State: Waiting for master to send event

                  Master_Host: 192.168.154.130

                  Master_User: slave

                  Master_Port: 3306

                Connect_Retry: 60

              Master_Log_File: slave-bin.000003

          Read_Master_Log_Pos: 106

               Relay_Log_File: relay-bin.000002

                Relay_Log_Pos: 251

        Relay_Master_Log_File: slave-bin.000003

             Slave_IO_Running: Yes

            Slave_SQL_Running: Yes



本文出自 “一万年太久,只争朝夕” 博客,请务必保留此出处http://zengwj1949.blog.51cto.com/10747365/1923915

MySQL之高可用架构—MHA