MHA工作原理

• 1 從宕機崩潰的master保存二進制日誌事件（binlog events）
• 2 識別含有最新更新的slave
• 3 應用差異的中繼日誌（relay log）到其他的slave
• 4 應用從master保存的二進制日誌事件（binlog events）
• 5 提升一個slave為新的master
• 6 使其他的slave連接新的master進行復制
• 註意：MHA需要基於ssh，key驗證登入方法

相關軟件包

• MHA監控服務器安裝:mha4mysql-manager-0.55-1.el5.noarch，mha4mysql-node-0.54-1.el5.noarch
• 其他主從集群服務器安裝:mha4mysql-node-0.54-1.el5.noarch

下面是實驗環境

• 四臺centos-7主機，一臺搭建MHA管理服務器，另外三臺，做一主二從架構
• 為了更容易理解實驗步驟我將服務器名稱分別用簡化字母表示：MHA服務器：MHA，master服務器：M1 ，slave服務器：S1 ,s2

首先去官網下載MHA軟件包，註意：需要×××

• 官網： https://code.google.com/archive/p/mysql-master-ha/
• mha4mysql-manager-0.55-1.el5.noarch
• mha4mysql-node-0.54-1.el5.noarch

一，配置主從復制集群架構

(一)，配置master服務器

1,修改配置文件

    vim /etc/my.cnf
    在[mysqld]語句塊中添加如下配置
    [mysqld]
    log-bin                 #開啟二進制日誌
    server_id=1               #設置所有節點中唯一的id編號
    innodb_file_per_table   #開啟數據於表結構分離，兩個文件存放
    skip_name_resolve=1     #跳過DNS解析
 

2，在M1上安裝剛才下載的MHA軟件包：mha4mysql-node-0.54-1.el5.noarch

    yum install mha4mysql-node-0.54-1.el5.noarch   

3，啟動mariadb服務

    systemctl start mariadb
    systemctl enable mariadb

4，運行數據庫安全程序

    "mysql_secure_installation"

        第一項問你：輸入root密碼  回車即可，因為沒有
        第二項問你：需要設置root密碼麽，
        第三項問你：需要刪除空賬號用戶麽，
        第四項問你：禁止root用戶遠程登入麽，
        第五項問你：需要刪除test測試數據庫麽，
        第六項問你：現在重新加載權限表嗎 ，

5，創建有復制權限的用戶賬號 ，以及用作與MHA服務器管理數據庫的用戶，該用戶必須擁有所有權限

    1，創建擁有復制權限的用戶賬號
        GRANT REPLICATION SLAVE  ON *.* TO ‘repluser‘@‘HOST‘ IDENTIFIED BY ‘replpass‘; 

            命令解析：
                ‘repluser‘@‘HOST‘ :設置用戶名即可登入的主機ip或網段，網段用%表示 例如10.0.0.%
                IDENTIFIED BY:設置密碼
                *.* ：表示所有數據庫，所有表
                GRANT REPLCATION SLAVE:就是允許該用戶復制數據

            該命令作用就是授權repluser能拷貝數據庫的所有內容
    2，創建MHA管理用戶
        GRANT REPLICATION SLAVE  ON *.* TO ‘mha‘@‘HOST‘ IDENTIFIED BY ‘replpass‘;  

            命令解析：
                ‘mha‘@‘HOST‘ :設置用戶名即可登入的主機ip或網段，網段用%表示 例如10.0.0.%
                IDENTIFIED BY:設置密碼
                *.* ：表示所有數據庫，所有表
                GRANT ALL :就表示該用戶擁有所有權限的意思

(二)，配置S1服務器

1，修改配文件

   vim /etc/my.cnf
    server_id=2
    read_only                   #普通用戶只有讀權限，對超級用戶沒有限制
    log-bin
    relay_log_purge=0           #不自動清理日誌
    skip_name_resolve=1
    innodb_file_per_table
    "log-bin"             
    "註意：正常來講MySQL主從復制，從服務器是不需要啟用二進制日誌的，
    這裏為什麽從服務器要啟用二進制日誌呢？因為基於MHA管理，當原master服務器down機了，
    MHA會自動提升一臺數據變化不是很大的從服務器為新的主，因為主必須開啟二進制日誌所以必須添加"

2，在M1上安裝剛才下載的MHA軟件包：mha4mysql-node-0.54-1.el5.noarch

    yum install mha4mysql-node-0.54-1.el5.noarch   

3，啟動mariadb服務

    systemctl start mariadb
    systemctl enable mariadb

4，運行數據庫安全程序

    "mysql_secure_installation"

        第一項問你：輸入root密碼  回車即可，因為沒有
        第二項問你：需要設置root密碼麽，
        第三項問你：需要刪除空賬號用戶麽，
        第四項問你：禁止root用戶遠程登入麽，
        第五項問你：需要刪除test測試數據庫麽，
        第六項問你：現在重新加載權限表嗎 ，

6，，使用有復制權限的用戶賬號連接至主服務器，並啟動復制線程

    1，使用有復制權限的用戶賬號連接至主服務器
        CHANGE MASTER TO 
             MASTER_HOST=‘master_host‘,         #指定master主機IP
             MASTER_USER=‘repluser‘,            #指定master被授權的用戶名
             MASTER_PASSWORD=‘replpass‘,        #指定被master授權的用戶密碼 MASTER_LOG_FILE=‘mysql-bin.xxxxx‘, #指定master服務器的哪個二進制日誌開始復制
             MASTER_LOG_POS=#;                  #二進制日誌位置，可以在master服務器上執行該命令查看，show master logs;

    2，啟動復制線程IO_THREAD和SQL_THREAD
         START SLAVE; 

7，查看slave服務器線程狀態

    MariaDB [(none)]> show slave status\G
    *************************** 1. row ***************************
                   Slave_IO_State: Waiting for master to send event
                      Master_Host: 192.168.68.17
                      Master_User: repluser
                      Master_Port: 3306
                    Connect_Retry: 60
                  Master_Log_File: mariadb-bin.000001
              Read_Master_Log_Pos: 557
                   Relay_Log_File: mariadb-relay-bin.000002
                    Relay_Log_Pos: 843
            Relay_Master_Log_File: mariadb-bin.000001
                 Slave_IO_Running: Yes  "重點關註如果是NO表示線程沒起來"
                Slave_SQL_Running: Yes "重點關註 如果是NO表示該線程沒起來"
                  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: 557
                  Relay_Log_Space: 1139
                  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 "該項表示同步時間 0表示即使同步"
    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: 1

(三)，在S2服務器上在把S1上的操作，按照同樣的步驟做一遍，完成S2的配置

主從復制測試

    1，在M1上創建數據庫
    MariaDB [(none)]> create database a1;
    Query OK, 1 row affected (0.00 sec)

    M1 [(none)]> show databases;
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | a1                 |
    | mysql              |
    | performance_schema |
    | test               |
    +--------------------+
    5 rows in set (0.00 sec)

    2，在S1，S2上查看同步情況。
    S1 [(none)]> show databases;
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | a1                 |
    | mysql              |
    | performance_schema |
    | test               |
    +--------------------+
    5 rows in set (0.01 sec)

    S2 [(none)]> show databases;
    +--------------------+
    | Database           |
    +--------------------+
    | information_schema |
    | a1                 |
    | mysql              |
    | performance_schema |
    | test               |
    +--------------------+
    5 rows in set (0.01 sec)

(四)，配置MHA服務器

1，實現所有主機SSH，基於key驗證登入方法，註意此方法只能使用於局域網

①，在任意一臺主機上生成一對公私鑰，例如，在M1上生成

    ssh-keygen
        這是候會在本機生成一個.ssh/目錄
            ls .ssh/
            id_rsa  id_rsa.pub 

②，然後再把整個.ssh/目錄復制給本機M1

    ssh-copy-id  M1_IP
        這時候本機.ssh目錄還會多兩個文件
            ls .ssh/
            authorized_keys  id_rsa  id_rsa.pub  known_hosts

③，將整個.ssh目錄復制到其他所有主機

    ssh-copy-id MHA_IP
    ssh-copy-id S1_IP
    ssh-copy-id S2_IP

④,ssh連接測試,不用輸入密碼表示成功

[root@MHA ~]# ssh 192.168.68.7
Last login: Fri Mar 30 13:21:52 2018 from 192.168.68.1
[root@master ~]#

原理：所有主機都是用的一個公鑰，其實這些主機會以為就是一臺主機，所以這個.ssh文件千萬不要泄露了，如果泄露了就意味著可以不需要密碼登入任意一臺主機，這就是為什麽只能在局域網中使用的原因，如果，想在公網使用的話，就需要在每一臺主機上生成公私鑰，在每一臺主機都互相復制一遍，或者是都復制到一臺主機上，再把這臺主機上的.ssh目錄下的authorized_keys 這個文件復制到其他的所有主機上

2，安裝兩個包：

• mha4mysql-manager-0.55-1.el5.noarch.rpm
• mha4mysql-node-0.54-1.el5.noarch

註意：需要配置epel源，用阿裏雲的epel源就可以

   yum install mha4mysql-manager-0.55-1.el5.noarch.rpm mha4mysql-node-0.54-1.el5.noarch.rpm 

3，創建一個存放MHA配置的目錄

    mkdir -pv /etc/mha/

4，在MHA配置目錄創建一個管理配置文件，文件名沒有要求。

    vim /etc/mha/app1.cnf

#添加如下項目

    [server default]                                          #默認規則
    user=mha                                                  #mhauser（mysql內配置的用來管理數據庫的用戶）
    password=123123                                           #密碼
    manager_workdir=/data/mha/test/                           #工作目錄
    manager_log=/data/mha/test/manager.log                    #日誌文件
    remote_workdir=/data/mha/test/                            #節點的工作目錄
    ssh_user=root                                             #ssh用戶
    repl_user=reluser                                         #主從復制用戶（mysql內配置的用來復制數據庫的用戶）
    repl_password=123123                                      #密碼
    ping_interval=1                                           #心跳檢測間隔（秒）

    [server1]                                                 #節點名稱
    hostname=172.18.30.1                                      #節點地址
    candidate_master=1                                        #表示允許提升為主服務器
    [server2]                                                 #節點名稱
    hostname=172.18.30.2                                      #節點地址
    candidate_master=1                                        #表示允許提升為主服務器
    [server3]                                                 #節點名稱
    hostname=172.18.30.4                                      #節點地址

5，利用MHA自帶的SSH檢測的腳本檢測SSH是否連接正常

    [root@test ~]# masterha_check_ssh --conf=/etc/mha/app1.cnf
    Sat Mar 31 19:18:47 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
    Sat Mar 31 19:18:47 2018 - [info] Reading application default configuration from /etc/mha/app1.cnf..
    Sat Mar 31 19:18:47 2018 - [info] Reading server configuration from /etc/mha/app1.cnf..
    Sat Mar 31 19:18:47 2018 - [info] Starting SSH connection tests..
    Sat Mar 31 19:18:49 2018 - [debug] 
    Sat Mar 31 19:18:47 2018 - [debug]  Connecting via SSH from [email protected](172.18.30.107:22) to [email protected](172.18.30.108:22)..
    Sat Mar 31 19:18:48 2018 - [debug]   ok.
    Sat Mar 31 19:18:48 2018 - [debug]  Connecting via SSH from [email protected](172.18.30.107:22) to [email protected](172.18.30.109:22)..
    Sat Mar 31 19:18:49 2018 - [debug]   ok.
    Sat Mar 31 19:18:50 2018 - [debug] 
    Sat Mar 31 19:18:47 2018 - [debug]  Connecting via SSH from [email protected](172.18.30.108:22) to [email protected](172.18.30.107:22)..
    Sat Mar 31 19:18:49 2018 - [debug]   ok.
    Sat Mar 31 19:18:49 2018 - [debug]  Connecting via SSH from [email protected](172.18.30.108:22) to [email protected](172.18.30.109:22)..
    Sat Mar 31 19:18:49 2018 - [debug]   ok.
    Sat Mar 31 19:18:50 2018 - [debug] 
    Sat Mar 31 19:18:48 2018 - [debug]  Connecting via SSH from [email protected](172.18.30.109:22) to [email protected](172.18.30.107:22)..
    Sat Mar 31 19:18:49 2018 - [debug]   ok.
    Sat Mar 31 19:18:49 2018 - [debug]  Connecting via SSH from [email protected](172.18.30.109:22) to [email protected](172.18.30.108:22)..
    Sat Mar 31 19:18:50 2018 - [debug]   ok.
    Sat Mar 31 19:18:50 2018 - [info] All SSH connection tests passed successfully.

6，利用MHA自帶的檢測復制狀況，檢測是否復制正常

    [root@test ~]# masterha_check_repl --conf=/etc/mha/app1.cnf 
    Sat Mar 31 19:19:26 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
    Sat Mar 31 19:19:26 2018 - [info] Reading application default configuration from /etc/mha/app1.cnf..
    Sat Mar 31 19:19:26 2018 - [info] Reading server configuration from /etc/mha/app1.cnf..
    Sat Mar 31 19:19:26 2018 - [info] MHA::MasterMonitor version 0.56.
    Sat Mar 31 19:19:28 2018 - [info] GTID failover mode = 0
    Sat Mar 31 19:19:28 2018 - [info] Dead Servers:
    Sat Mar 31 19:19:28 2018 - [info] Alive Servers:
    Sat Mar 31 19:19:28 2018 - [info]   172.18.30.107(172.18.30.107:3306)
    Sat Mar 31 19:19:28 2018 - [info]   172.18.30.108(172.18.30.108:3306)
    Sat Mar 31 19:19:28 2018 - [info]   172.18.30.109(172.18.30.109:3306)
    Sat Mar 31 19:19:28 2018 - [info] Alive Slaves:
    Sat Mar 31 19:19:28 2018 - [info]   172.18.30.108(172.18.30.108:3306)  Version=5.5.56-MariaDB (oldest major version between slaves) log-bin:enabled
    Sat Mar 31 19:19:28 2018 - [info]     Replicating from 172.18.30.107(172.18.30.107:3306)
    Sat Mar 31 19:19:28 2018 - [info]     Primary candidate for the new Master (candidate_master is set)
    Sat Mar 31 19:19:28 2018 - [info]   172.18.30.109(172.18.30.109:3306)  Version=5.5.56-MariaDB (oldest major version between slaves) log-bin:enabled
    Sat Mar 31 19:19:28 2018 - [info]     Replicating from 172.18.30.107(172.18.30.107:3306)
    Sat Mar 31 19:19:28 2018 - [info]     Primary candidate for the new Master (candidate_master is set)
    Sat Mar 31 19:19:28 2018 - [info] Current Alive Master: 172.18.30.107(172.18.30.107:3306)
    Sat Mar 31 19:19:28 2018 - [info] Checking slave configurations..
    Sat Mar 31 19:19:28 2018 - [info]  read_only=1 is not set on slave 172.18.30.108(172.18.30.108:3306).
    Sat Mar 31 19:19:28 2018 - [warning]  relay_log_purge=0 is not set on slave 172.18.30.108(172.18.30.108:3306).
    Sat Mar 31 19:19:28 2018 - [info]  read_only=1 is not set on slave 172.18.30.109(172.18.30.109:3306).
    Sat Mar 31 19:19:28 2018 - [warning]  relay_log_purge=0 is not set on slave 172.18.30.109(172.18.30.109:3306).
    Sat Mar 31 19:19:28 2018 - [info] Checking replication filtering settings..
    Sat Mar 31 19:19:28 2018 - [info]  binlog_do_db= , binlog_ignore_db= 
    Sat Mar 31 19:19:28 2018 - [info]  Replication filtering check ok.
    Sat Mar 31 19:19:28 2018 - [info] GTID (with auto-pos) is not supported
    Sat Mar 31 19:19:28 2018 - [info] Starting SSH connection tests..
    Sat Mar 31 19:19:31 2018 - [info] All SSH connection tests passed successfully.
    Sat Mar 31 19:19:31 2018 - [info] Checking MHA Node version..
    Sat Mar 31 19:19:32 2018 - [info]  Version check ok.
    Sat Mar 31 19:19:32 2018 - [info] Checking SSH publickey authentication settings on the current master..
    Sat Mar 31 19:19:33 2018 - [info] HealthCheck: SSH to 172.18.30.107 is reachable.
    Sat Mar 31 19:19:34 2018 - [info] Master MHA Node version is 0.56.
    Sat Mar 31 19:19:34 2018 - [info] Checking recovery script configurations on 172.18.30.107(172.18.30.107:3306)..
    Sat Mar 31 19:19:34 2018 - [info]   Executing command: save_binary_logs --command=test --start_pos=4 --binlog_dir=/var/lib/mysql,/var/log/mysql --output_file=/data/mastermha/app1//save_binary_logs_test --manager_version=0.56 --start_file=mariadb-bin.000001 
    Sat Mar 31 19:19:34 2018 - [info]   Connecting to [email protected](172.18.30.107:22).. 
      Creating /data/mastermha/app1 if not exists..    ok.
      Checking output directory is accessible or not..
       ok.
      Binlog found at /var/lib/mysql, up to mariadb-bin.000001
    Sat Mar 31 19:19:34 2018 - [info] Binlog setting check done.
    Sat Mar 31 19:19:34 2018 - [info] Checking SSH publickey authentication and checking recovery script configurations on all alive slave servers..
    Sat Mar 31 19:19:34 2018 - [info]   Executing command : apply_diff_relay_logs --command=test --slave_user=‘mha‘ --slave_host=172.18.30.108 --slave_ip=172.18.30.108 --slave_port=3306 --workdir=/data/mastermha/app1/ --target_version=5.5.56-MariaDB --manager_version=0.56 --relay_log_info=/var/lib/mysql/relay-log.info  --relay_dir=/var/lib/mysql/  --slave_pass=xxx
    Sat Mar 31 19:19:34 2018 - [info]   Connecting to [email protected](172.18.30.108:22).. 
      Checking slave recovery environment settings..
        Opening /var/lib/mysql/relay-log.info ... ok.
        Relay log found at /var/lib/mysql, up to mariadb-relay-bin.000002
        Temporary relay log file is /var/lib/mysql/mariadb-relay-bin.000002
        Testing mysql connection and privileges.. done.
        Testing mysqlbinlog output.. done.
        Cleaning up test file(s).. done.
    Sat Mar 31 19:19:35 2018 - [info]   Executing command : apply_diff_relay_logs --command=test --slave_user=‘mha‘ --slave_host=172.18.30.109 --slave_ip=172.18.30.109 --slave_port=3306 --workdir=/data/mastermha/app1/ --target_version=5.5.56-MariaDB --manager_version=0.56 --relay_log_info=/var/lib/mysql/relay-log.info  --relay_dir=/var/lib/mysql/  --slave_pass=xxx
    Sat Mar 31 19:19:35 2018 - [info]   Connecting to [email protected](172.18.30.109:22).. 
      Checking slave recovery environment settings..
        Opening /var/lib/mysql/relay-log.info ... ok.
        Relay log found at /var/lib/mysql, up to mariadb-relay-bin.000002
        Temporary relay log file is /var/lib/mysql/mariadb-relay-bin.000002
        Testing mysql connection and privileges.. done.
        Testing mysqlbinlog output.. done.
        Cleaning up test file(s).. done.
    Sat Mar 31 19:19:36 2018 - [info] Slaves settings check done.
    Sat Mar 31 19:19:36 2018 - [info] 
    172.18.30.107(172.18.30.107:3306) (current master)
     +--172.18.30.108(172.18.30.108:3306)
     +--172.18.30.109(172.18.30.109:3306)

    Sat Mar 31 19:19:36 2018 - [info] Checking replication health on 172.18.30.108..
    Sat Mar 31 19:19:36 2018 - [info]  ok.
    Sat Mar 31 19:19:36 2018 - [info] Checking replication health on 172.18.30.109..
    Sat Mar 31 19:19:36 2018 - [info]  ok.
    Sat Mar 31 19:19:36 2018 - [warning] master_ip_failover_script is not defined.
    Sat Mar 31 19:19:36 2018 - [warning] shutdown_script is not defined.
    Sat Mar 31 19:19:36 2018 - [info] Got exit code 0 (Not master dead).

    MySQL Replication Health is OK.

7，啟動MHA，註意運行這個命令是前臺運行，終端會一直卡著

    [root@test ~]# masterha_manager --conf=/etc/mha/app1.cnf
    Sat Mar 31 19:23:26 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
    Sat Mar 31 19:23:26 2018 - [info] Reading application default configuration from /etc/mha/app1.cnf..
    Sat Mar 31 19:23:26 2018 - [info] Reading server configuration from /etc/mha/app1.cnf..

8，主從切換測試

我們手動宕掉M1主機，在理論上來說MHA會將S1機器該接替Master服務器，並自動踢除M1主機，最終S1為master，S2為slave服務器。

1,宕掉M1上的mariadb服務

    systemctl  stop mariadb

2，登入S1上查看狀況

    MariaDB [(none)]> show master logs;
    +--------------------+-----------+
    | Log_name           | File_size |
    +--------------------+-----------+
    | mariadb-bin.000001 |       715 |
    | mariadb-bin.000002 |       245 |
    +--------------------+-----------+
    2 rows in set (0.00 sec)

    MariaDB [(none)]> show slave status;
    Empty set (0.00 sec)

    MariaDB [(none)]> show variables like ‘%read_only%‘;
    +------------------+-------+
    | Variable_name    | Value |
    +------------------+-------+
    | innodb_read_only | OFF   |
    | read_only        | OFF   |
    | tx_read_only     | OFF   |
    +------------------+-------+
    3 rows in set (0.00 sec)
    "我們可以看出，MHA已經完成了切換，之前在B主機設置的read_only選項也已經關閉了。"

3，登入S2上查看情況

        MariaDB [(none)]> show slave status\G
    *************************** 1. row ***************************
                   Slave_IO_State: Waiting for master to send event
                      Master_Host: 172.18.30.108
                      Master_User: repluser
                      Master_Port: 3306
                    Connect_Retry: 60
                  Master_Log_File: mariadb-bin.000002
              Read_Master_Log_Pos: 245
                   Relay_Log_File: mariadb-relay-bin.000002
                    Relay_Log_Pos: 531
            Relay_Master_Log_File: mariadb-bin.000002
                 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: 245
                  Relay_Log_Space: 827
                  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: 2
    1 row in set (0.00 sec)

    "可以看出，S2主機已經將同步服務器改為了S1主機

    測試完成。"

搭建MHA排錯過程

錯誤1

    [root@test ~]# masterha_check_ssh --conf=/etc/mha/app1.cnf
    Sat Mar 31 20:14:26 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
    Sat Mar 31 20:14:26 2018 - [info] Reading application default configuration from /etc/mha/app1.cnf..
    Sat Mar 31 20:14:26 2018 - [info] Reading server configuration from /etc/mha/app1.cnf..
    Sat Mar 31 20:14:26 2018 - [error][/usr/share/perl5/vendor_perl/MHA/Config.pm, ln383] Block name "server" is invalid. Block name must be "server default" or start from "server"(+ non-whitespace characters).
    Block name "server" is invalid. Block name must be "server default" or start from "server"(+ non-whitespace characters). at /usr/share/perl5/vendor_perl/MHA/SSHCheck.pm line 148.

    "註意:這個問題出在自己創建的MHA配置文件中的被管理的節點沒有排序[server]下面是錯誤文件"
    [server default]
    user=mha
    password=centos
    manager_workdir=/data/mastermha/app1/
    manager_log=/data/mastermha/app1/manager.log
    remote_workdir=/data/mastermha/app1/
    ssh_user=root
    repl_user=repluser
    repl_password=centos
    ping_interval=1

    "[server]" <-
    hostname=172.18.30.107
    candidate_master=1

    "[server]" <-
    hostname=172.18.30.108
    candidate_master=1

    "[server]" <-
    hostname=172.18.30.109
    candidate_master=1

    "正確配置,仔細查看有什麽配置不同"

    [server default]
    user=mha
    password=centos
    manager_workdir=/data/mastermha/app1/
    manager_log=/data/mastermha/app1/manager.log
    remote_workdir=/data/mastermha/app1/
    ssh_user=root
    repl_user=repluser
    repl_password=centos
    ping_interval=1

    "[server1]"
    hostname=172.18.30.107
    candidate_master=1

    "[server2]"
    hostname=172.18.30.108
    candidate_master=1

    "[server3]"
    hostname=172.18.30.109
    candidate_master=1

錯誤2

如果出現下面的問題說明是有一個庫找不到，需要在每一個節點都創建一個軟連接
    [root@centos-MHA ~]# masterha_check_ssh  --conf=/etc/mha/app1.cnf
    Can‘t locate MHA/SSHCheck.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at /usr/bin/masterha_check_ssh line 25.
    BEGIN failed--compilation aborted at /usr/bin/masterha_check_ssh line 25.

    [root@centos-MHA ~]# ln -s /usr/lib/perl5/vendor_perl/MHA/ /usr/lib64/perl5/vendor_perl/
    [root@centos-M1 ~]# ln -s /usr/lib/perl5/vendor_perl/MHA/ /usr/lib64/perl5/vendor_perl/
    [root@centos-S1 ~]# ln -s /usr/lib/perl5/vendor_perl/MHA/ /usr/lib64/perl5/vendor_perl/
    [root@centos-S2 ~]# ln -s /usr/lib/perl5/vendor_perl/MHA/ /usr/lib64/perl5/vendor_perl/

實現MHA，MySQL高可用集群架構